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  • hypertension  (31)
  • Liquid chromatography  (26)
  • Springer  (57)
  • PANGAEA
  • Periodicals Archive Online (PAO)
  • 2005-2009
  • 1980-1984  (57)
  • 1982  (57)
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  • 2005-2009
  • 1980-1984  (57)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 21 (1982), S. 287-291 
    ISSN: 1432-1041
    Keywords: tolmesoxide ; hypertension ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Tolmesoxide is a new, direct-acting vasodilator drug for use in the management of both hypertension and cardiac failure. In 6 essential hypertensives inadequately controlled by combined β-blocker and diuretic therapy (average supine blood pressure 178/103 mm Hg) the addition of tolmesoxide (300–900 mg daily) was associated with a significant improvement in blood pressure control (average supine blood pressure 161/89 mmHg). The effect of food on the pharmacokinetics and pharmacodynamics of tolmesoxide have also been studied because, particularly at higher doses, the drug has been associated with upper gastrointestinal upset and it has been empirically recommended that it be taken with food. The blood pressure and heart rate responses were not significantly different when tolmesoxide was taken fasting or with food. Food resulted in a significant reduction in the peak plasma tolmesoxide concentration (2.14 µg/ml compared to 2.97 µg/ml) and a significant increase in the time to reach peak plasma concentration (1.67 h compared to 0.63 h). Although there was no impairment of its hypotensive effect, food significantly altered the pharmacokinetics of tolmesoxide and may therefore be useful in reducing the gastrointestinal disturbance associated with its use. In the treatment of inadequately controlled hypertension, tolmesoxide has a limited role as an alternative vasodilator.
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  • 2
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    Springer
    European journal of clinical pharmacology 21 (1982), S. 363-367 
    ISSN: 1432-1041
    Keywords: labetalol ; clonidine ; hypertension ; dose titration ; bendrofluazide ; side effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The antihypertensive effect of labetalol (L) was compared with that of clonidine (C) in a randomized cross-over study in 17 hypertensive outpatients on bendrofluazide (B). After treatment for two weeks with B (5 mg qd), either L (100 mg tid) or C (0.1 mg tid) was given and their doses were titrated at 2-weekly visits until normotension was achieved, or intolerable side-effects occurred. The treatment with B and L or C was then continued in a cross-over fashion for two 6-week periods, with 3 week diuretic washouts and subsequent dose-titration periods between the treatment periods. At the end of B, the supine blood pressure (BP) was 156/101, and at the end of B + L and B + C it was 136/91 (p〈0.001) and 137/91 (p〈0.001), respectively, pooling the data from both periods. At the end of B, the standing BP was 155/115, and at the end of B + L and B + C 134/100 (p〈0.001) and 139/106 (p〈0.001), respectively. The mean daily doses required were L 476mg and C 0.335 mg. On a weight basis, labetalol had about 1/1400 of the potency of clonidine. 12 patients complained of tiredness and dry mouth on clonidine and 2 patients of unsteadiness on labetalol. Labetalol caused a psoriasiform rash on the hands in one patient and limb weakness in one patient.
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  • 3
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    European journal of clinical pharmacology 22 (1982), S. 7-14 
    ISSN: 1432-1041
    Keywords: prazosin ; baroreflexes ; hypertension ; reflex tachycardia ; alpha adrenergic blockade ; dopamine-beta-hydroxylase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Prazosin is a post synaptic alpha adrenergic blocker effective in hypertension, whose hypotensive effect is unaccompanied by reflex tachycardia or hyperreninemia, nor by other evidence of increased sympathetic activity. We studied the baroreceptor reflex arc as a potential mediator of these effects. Twenty-two essential hypertensive men were treated with prazosin alone versus placebo, and experienced a blood pressure fall (from 114.8±3.6 down to 101.1±2.5 mm Hg,p〈0.005) unaccompanied by any change in heart rate, plasma renin activity, or several other indices of sympathetic nervous system activity (plasma dopamine-β-hydroxylase activity; urinary excretion of free catecholamines and vanillyl mandelic acid; allp〉0.1). Concomitant with the blood pressure fall, there was a significant depression of baroreflex arc sensitivity, from 11.4±2.0 ms/mmHg down to 6.6±1.9 ms/mmHg (p〈0.05), without an associated change in cardiac vagal inhibition (291.2±46.2 versus 300.3±19.2 ms,p〉0.1). Baroreflex arc sensitivity depression may in part explain the lack of reflex sympathetic outflow noted during prazosin treatment of hypertension.
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  • 4
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    European journal of clinical pharmacology 22 (1982), S. 197-201 
    ISSN: 1432-1041
    Keywords: hypertension ; oxprenolol ; indomethacin ; drug interaction ; hypotensive effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary A double-blind, cross-over study in 16 patients with essential hypertension was carried out, to evaluate any possible interference by indomethacin, a known prostaglandin-synthetase inhibitor, with the antihypertensive effect of oxprenolol, a non-selective beta-adrenoceptor blocking agent. Both indomethacin and oxprenolol, as well as the two drugs combined, inhibited plasma renin activity; no change was found in urinary sodium excretion or body weight. Oxprenolol alone caused a highly significant decrease in the systolic (−10.4 mmHg,p〈0.001), diastolic (−7.4 mmHg,p〈0.001) and mean (−7.7 mmHg,p〈0.01) blood pressures, whereas indomethacin did not influence blood pressure. When the two drugs were given in combination, blood pressure decreased (systolic: −5.9 mmHg; diastolic: −4.0 mmHg; mean: −4.6 mmHg), but the changes induced in blood pressure were reduced by about 50% when compared with those in the oxprenolol alone period. The data show that indomethacin seems to interfere with the antihypertensive effect of oxprenolol, by an action which may be due to the inhibition of prostaglandin synthesis.
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  • 5
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    European journal of clinical pharmacology 22 (1982), S. 495-499 
    ISSN: 1432-1041
    Keywords: hypertension ; cyclothiazide ; hydrochlorthiazide ; thiazide diuretics ; potassium-sparing diuretics ; saluretic effect ; hypokalaemia ; hyperuricaemia ; amiloride
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The antihypertensive, saluretic and hypokalaemic effects of a small dose of cyclothiazide (2.5 mg daily) were compared with those of a conventional dose of an hydrochlorthiazide-amiloride hydrochloride combination (50+5 mg daily). Both preparations were given to 13 patients with mild (WHO I) hypertension in a cross-over manner for six weeks, with an intervening wash-out phase of three weeks. The antihypertensive efficacy of cyclothiazide was well comparable to that of the hydrochlorthiazide-amiloride combination, although cyclothiazide tended to inhibit renal sodium reabsorption less than the combination. Cyclothiazide tended to cause hypokalaemia, apparently due to increased potassium loss, but with the present dosage none of the 13 patients developed marked hypokalaemia (serum potassium less than 3.3 mmol/l). Both drugs led to a comparable increase in serum urate concentration. Neither of the preparations affected creatinine or free-water clearance. The results suggest that even in relatively small doses thiazides effectively decrease blood pressure, and combining thiazides with potassium-sparing diuretics is advantageous only in patients with marked hypokalaemia and its associated risks.
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  • 6
    ISSN: 1432-1041
    Keywords: beta-blocker ; hypertension ; clonidine ; plasma catecholamines ; metoprolol ; propranolol ; blood pressure responses ; isometric work ; dynamic work
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The effects of metropolol (beta1-selective), propranolol (nonselective) and clonidine (central alpha-stimulant) on plasma norepinephrine, blood pressure and heart rate were assessed at rest, during isometric work and dynamic exercise in 15 patients with moderate hypertension. Metroprolol resulted in a lower diastolic blood pressure during isometric and dynamic exercise than propranolol, which was paralleled by a lower plasma norepinephrine level during dynamic work; both beta-adrenergic blocking compounds resulted in a lower heart rate in all test situations than that obtained with clonidine; clonidine produced similar control of diastolic blood pressure to that obtained with the beta-adrenergic blocking agents, but did not clearly attenuate the systolic blood pressure response to dynamic exercise. Plasma norepinephrine concentrations tended to be lowest following clonidine, especially during dynamic work. The findings support the hypothesis that the central action of clonidine inhibits peripheral release of norepinephrine, but is insufficient to attenuate cardiac stimulation by physical exercise. The fact that propranolol caused higher plasma norepinephrine concentrations than metoprolol during exercise may explain the difference in the blood pressure responses during exercise.
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  • 7
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    European journal of clinical pharmacology 21 (1982), S. 445-449 
    ISSN: 1432-1041
    Keywords: pindolol ; hypertension ; retard formulation ; plasma levels ; side effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary 36 out of 52 patients with essential hypertension, whose blood pressure was not normalized with pindolol 15 mg per day, were treated with 30 mg per day for four to six weeks. Pindolol was administered in random order, either as 15 mg twice daily or as one 30 mg retard tablet once daily. Blood pressure was lowered from mean pretreatment levels of 174/111 mmHg to 149/98 mmHg by 15 mg b.d., and to 145/97 mmHg by 30 mg retard. In five patients diurnal variations in blood pressure and plasma pindolol levels were determined. At all times during the day blood pressure was at least as well controlled by 30 mg retard as by 15 mg b.d. Plasma concentration maxima were similar with both forms, but a higher concentration was maintained for a longer time after the retard tablet. Pindolol 30 mg was well tolerated and the incidence of side effects was lower than during treatment with 15 mg b.d. Thus, patients requiring high doses of pindolol for control of hypertension can safely and conveniently be treated with a single tablet of 30 mg pindolol retard.
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  • 8
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    European journal of clinical pharmacology 21 (1982), S. 473-477 
    ISSN: 1432-1041
    Keywords: tolmesoxide ; vasodilators ; heart failure ; haemodynamics ; hypertension ; sulphoxide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The haemodynamic effect of Tolmesoxide, a new sulphoxide chemically dissimilar from other vasodilators, was investigated in eight patients with chronic heart failure subsequent to ischaemic heart disease and/or hypertension. Tolmesoxide significantly increased the cardiac output and reduced the indices of systemic vascular resistance, the mean pulmonary arterial pressure and left ventricular filling pressure in most patients studied. These changes were observed both as acute and chronic effects. No significant effect on the mean arterial pressure, heart rate or myocardial oxygen supply/demand was observed. Tolmesoxide appeared to be therapeutically potent by both intravenous and oral routes.
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  • 9
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    European journal of clinical pharmacology 22 (1982), S. 285-288 
    ISSN: 1432-1041
    Keywords: hypertension ; plasma adrenaline ; plasma noradrenaline ; isoprenaline response ; noradrenaline response ; salivation ; parasympathetic nervous system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Parameters of the autonomic nervous system were studied in normotensive subjects (NT; standing blood pressure (BP)≤125/85 mmHg) and in subjects with borderline hypertension (BHT; 140/90≤standing BP〈60/100 mmHg). No differences in plasma noradrenaline and adrenaline levels were found between NT and BHT subjects, neither at rest nor during exercise at 75% of maximum work capacity. The dose of noradrenaline required to increase systolic BP by 10 mmHg was significantly higher in NT than in BHT subjects (5.13±0.42 vs 3.50±0.57 µg · min−1). No difference between NT and BHT subjects was found in the dose of isoprenaline required to increase heart rate by 20 beats · min−1 (1.21±0.12 vs 1.09±0.11 µg · min−1). Resting salivary flow was significantly lower in BHT than in NT subjects (0.39±0.06 vs 0.98±0.06 g · min−1), suggesting decreased parasympathetic activity in the former group. The enhanced pressor effect of noradrenaline, together with the decreased parasympathetic activity, could explain the elevated blood pressure and heart rate in subjects with borderline hypertension.
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  • 10
    ISSN: 1432-1041
    Keywords: bopindolol ; hypertension ; beta-blocker ; blood pressure ; plasma renin ; plasma catecholamines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Bopindolol (LT 31-200), a new, long-acting, non-selective beta-blocker, was given as monotherapy to 13 patients, 12 with essential hypertension and 1 with renovascular hypertension. After a placebo period of 4–6 weeks, bopindolol was given once daily, starting with 1 mg and subsequently increasing at two-weekly intervals to 2 and 4 mg once daily until a diastolic blood pressure⩽90 mmHg was achieved. The effective dose was continued for 12 weeks. In 10 patients plasma levels of renin, noradrenaline, adrenaline and cholesterol were measured during placebo and after 3 months of therapy. Blood pressure and heart rate were lowered significantly during bopindolol treatment. The mean effective dose was 2.2 mg per day. In 10/13 patients a diastolic blood pressure⩽90 mmHg was achieved. Side effects were minimal. Changes in plasma noradrenaline and adrenaline were small and not significant, but renin and cholesterol were significantly reduced. Thus, LT 31-200 is an effective and well tolerated beta-blocker when given in a once daily dosage.
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  • 11
    ISSN: 1432-1041
    Keywords: hypertension ; nifedipine ; beta-adrenoceptor blockade ; long-term treatment ; adverse effects ; propranolol ; timolol ; metoprolol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The antihypertensive effect of nifedipine during long-term therapy was investigated in 5 patients receiving nifedipine as the sole drug and in 10 patients who had nifedipine in combination with a beta-adrenoceptor blocking drug. Nifedipine monotherapy was problematic because of side-effects and development of resistance to therapy after a few months. In patients who received the combined therapy significant and stable blood pressure reductions were maintained during the whole observation period (12–33 months). However, the occurrence of peripheral oedema in 4 of the patients necessitated the addition of a thiazide diuretic. It is concluded that nifedipine is not a first choice drug for the long-term treatment of arterial hypertension. When given in addition to a beta-blocker it is well tolerated and powerful but fluid retention may occur and if not counteracted by a diuretic it will limit the antihypertensive potential of the drug.
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  • 12
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    European journal of clinical pharmacology 23 (1982), S. 197-201 
    ISSN: 1432-1041
    Keywords: nifedipine ; hypertension ; low dose ; plasma concentration ; acute and long-term treatment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The acute and long-term hypotensive effects of low doses of nifedipine, and the correlation between the fall in the blood pressure (BP) and the plasma nifedipine concentration, were investigated in patients with essential hypertension. The oral administration of nifedipine 5 mg rapidly decreased BP from 163±22/101±10 to 127±12/82±9 mmHg (mean±SD; p〈0.001), and increased heart rate from 72±8 to 76±6 beats/min (p〈0.05), plasma renin activity rose from 1.2±0.6 to 1.4±0.8 ng/ml/h (p〈0.05), and plasma nifedipine concentration was 75.6±22.0 ng/ml 30 min after administration (n=7). The nifedipine concentration was significantly correlated both with the fall in BP (r=0.410, p〈0.02, n=31) and the rise in the heart rate (r=0.412, p〈0.02, n=31). Treatment with nifedipine 5 mg t.d.s. alone or in combination either with propranolol 10 mg t.d.s., or thiazide 1 tablet daily, or propranolol and thiazide, controlled BP in 36 patients during the 22 week study period. During the long-term nifedipine therapy, the plasma nifedipine level was significantly correlated with the fall in systolic (r=0.577, p〈0.01, n=20) and diastolic (r=0.595, p〈0.01, n=20) BP. It was concluded that the plasma nifedipine concentration could be correlated with the fall in BP, and that low doses of nifedipine, either as monotherapy or in combination, were effective in the acute and long-term treatment of patients with essential hypertension.
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  • 13
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    European journal of clinical pharmacology 23 (1982), S. 215-220 
    ISSN: 1432-1041
    Keywords: hypertension ; muzolimine ; mild renal functional impairment ; diuretic treatment ; body sodium ; catecholamines ; cardiovascular pressor responsiveness
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Eighteen patients with mild impairment of renal function (glomerular filtration rate 65±5 ml/min: m±SEM) and hypertension (168/105±6/3 mmHg) were shown on average to have abnormally increased cardiovascular pressor responsiveness to infused norepinephrine (NE; p〈0.05), whereas plasma and urinary NE, exchangeable body sodium and blood-volume did not differ significantly from normal. A slightly increased pressor responsiveness to angiotensin II was associated with a tendency to low plasma renin activity (PRA). Compared to placebo conditions, treatment with the loop-diuretic muzolimine in a mean dose of 35±2 mg/day for six weeks decreased blood-pressure and exchangeable sodium (p〈0.05), and NE pressor responsiveness was restored to normal values, whilst plasma and urinary NE were not significantly changed. This was consistent with improvement of the initially abnormal relationship between NE levels and NE responsiveness factors. In contrast, the pressor dose of angiotensin II and PRA were increased to an approximatively similar extent during muzolimine treatment. These observations suggest that removal of body sodium and a decrease in NE reactivity without an equivalent increase in sympathetic nervous activity may be important complementary factors in the antihypertensive mechanisms of diuretic treatment in patients with mild renal functional impairment.
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  • 14
    ISSN: 1432-1041
    Keywords: prizidilol ; vasodilator ; hypertension ; beta blocker ; plasma renin ; aldosterone ; catecholamines ; acetylator type
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Prizidilol is a new antihypertensive agent reported to possess combined precapillary vasodilator and betareceptor-blocking properties. To clarify the profile of the acute effects of prizidilol in man, a variable dose study was performed in 8 patients with benign essential hypertension. Blood pressure, heart rate, plasma renin activity, aldosterone, plasma and urinary catecholamines and electrolytes were determined at short intervals before and up to 23 h after oral administration of placebo and prizidilol 150, 300 and 600 mg. The 4 studies were performed at weekly intervals according to a Latin square design. Prizidilol produced dose-dependent decreases in supine and upright blood pressure, with an initial change after about 2 h and maximal effects from 4 to 8 h after drug ingestion. Following a high dose of prizidilol, supine mean blood pressure (average 128 mmHg prior to treatment) was normalised (〈107 mmHg) from 3 to 7 h and was still below predose levels 23 h after ingestion. The only reported side effects were postural dizziness in 2 cases (corresponding to a fall in systolic upright blood pressure to 〈95 mmHg) and headache in one case. A biphasic variation in heart rate and plasma renin activity, with an early drop and a subsequent tendency to a slight rise, was observed after an intermediate or high dose of prizidilol. Plasma norepinephrine levels were increased by a high dose of prizidilol, while plasma epinephrine, aldosterone and plasma and urinary electrolytes were not consistently changed. Prizidilol in a single oral dose appeared to be a potent antihypertensive agent. The profile of heart rate and plasma renin point to early dominance of beta-blockade followed by appearance of the concomitant vasodilator properties of prizidilol.
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  • 15
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    European journal of clinical pharmacology 21 (1982), S. 263-267 
    ISSN: 1432-1041
    Keywords: hypertension ; spironolactone ; hypotensive action ; peripheral circulation ; plethysmography ; handgrip test ; cold pressure test
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Since there is only scanty, indirect information about the mechanism of the hypotensive effect of spironolactone, 9 patients with essential hypertension were studied according to a randomised double-blind, cross-over protocol. Spironolactone 100mg b.i.d. and placebo were each given for one month and the following parameters were studied: blood pressure, heart rate, response to cold pressure and hand-grip tests, as well as blood flow in the calf and finger vessels. Flow in the calf and fingers representing muscle and skin arteries, respectively, was measured semicontinuously with an ECG-triggered venous occlusion plethysmograph. After spironolactone there was a significant decrease in the systolic and diastolic blood pressures in the supine, sitting and standing positions; the sitting systolic and diastolic blood pressure decreased by (mean ± SE) 27±4mm Hg (p〈0.001) and 11±4mm Hg (p〈0.02), respectively. No orthostatic response was observed. Heart rate remained unchanged. Blood flow through muscle and skin vessels increased in 6 out of 9 patients, and in these patients calculated vascular resistance in these areas decreased. Spironolactone did not significantly change the response of systemic blood pressure to the handgrip and cold pressure tests. The present data confirm the hypotensive properties of spironolactone and show that this effect is associated with dilatation of muscle and skin arteries in many but not in all the patients. The data do not support the hypothesis that spironolactone decreases the responsiveness of systemic blood pressure to orthosympathetic stimulation.
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  • 16
    ISSN: 1432-1041
    Keywords: hypertension ; indapamide ; pindolol ; plasma renin activity ; plasma aldosterone concentration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Sixteen patients with essential hypertension completed a double blind factorial trial comparing the effects of indapamide (2.5 mg daily) and pindolol (10 mg daily) on blood pressure, heart rate, plasma renin activity and plasma aldosterone concentration. There were four randomised test phases of eight weeks each during which patients received indapamide alone, pindolol alone, indapamide plus pindolol and no active treatment (placebo). Blood pressure and heart rate were measured every two weeks. Supine mean arterial pressure fell from 117 mm Hg in the placebo phase to 111 mm Hg in the indapamide phase, 106 mm Hg in the pindolol phase and 103 mm Hg in the combined indapamide plus pindolol phase. Factorial analysis confirmed that the hypotensive effects of the two drugs were additive, without evidence of potentiation or antagonism. Indapamide caused significant reductions in plasma potassium and chloride, and increases in plasma bicarbonate and urate concentrations; it also caused increases in plasma renin activity and aldosterone concentration. These changes are similar to those observed with thiazide diuretics.
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  • 17
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    European journal of clinical pharmacology 22 (1982), S. 487-489 
    ISSN: 1432-1041
    Keywords: nadolol ; hypertension ; effective dose range ; compliance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary An open, observer-blind, therapeutic titration trial was carried out in 28 patients with mild or moderate essential hypertension to determine the effective dose range of nadolol given once a day. 11 patients became normotensive (supine diastolic blood pressure 90 mm Hg or below) with 80 mg, 4 with 120 mg and 1 with 160 mg. The largest step in the reduction of blood pressure was achieved with the first dose step of 80 mg, and only a small, non-significant further decrease was obtained with higher dose levels. Thus, nadolol, unlike propranolol, has a narrow effective dose range, and this should permit a brief dose adjustment period, which would be important in improving patient compliance.
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  • 18
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    European journal of clinical pharmacology 23 (1982), S. 93-97 
    ISSN: 1432-1041
    Keywords: tolmesoxide ; vasodilator ; hypertension ; pharmacokinetics ; haemodynamics ; plasma renin activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The haemodynamic response and pharmacokinetics of single dose oral tolmesoxide were studied at various dose levels in 4 patients with severe hypertension. There was a reproducible fall in mean arterial pressure from baseline of 24.2% and a rise in heart rate of 37.6% following administration of tolmesoxide. The onset of antihypertensive action occurred within 1 h, with a peak effect at 3 h after dosing. The mean duration of action was up to 12.0 h. Tolmesoxide had a mean half-life of 3.0 h. It was rapidly absorbed with a mean peak plasma level occurring at 1.0 h. Plasma levels correlated well with the doses administered. Side-effects included mild nausea, facial flushing and postural symptoms.
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  • 19
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    European journal of clinical pharmacology 21 (1982), S. 457-460 
    ISSN: 1432-1041
    Keywords: hypertension ; propranolol ; hydralazine ; labetalol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary In a randomised cross-over trial the combination labetalol/hydrochlorothiazide was compared with the combination of propranolol/hydralazine/hydrochlorothiazide in 34 uncomplicated hypertensive patients, who were not satisfactorily controlled with hydrochlorothiazide 50 mg alone. The elevated diastolic pressure (D.P.) in 27 patients responded satisfactorily to the labetalol schedule and in 28 patients to the propranolol/hydralazine schedule. No difference was found in the rate of decrease of D.P., nor in the disappearance of hypertension — related complaints. Although the duration of the washout between treatments was at least one month, treatment was significantly more efficacious during the second period. Labetalol pre-treatment especially seemed to enhance the effect of subsequent propranolol/hydralazine administration. Side effects due to therapy were rare and were not related to any particular treatment. The median daily dose of labetalol in responders was 600 mg and that of propranolol/hydralazine 120/60 mg (in both therapies hydrochlorothiazide 50 mg was given in addition). Patients showed a slight preference for the labetaol medication. It is concluded that labetalol/hydrochlorothiazide and propranolol/hydralazine/hydrochlorothiazide are equally satisfactory in the treatment of uncomplicated hypertension.
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  • 20
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    European journal of clinical pharmacology 22 (1982), S. 203-206 
    ISSN: 1432-1041
    Keywords: hypertension ; ticrynafen ; hydrochlorothiazide ; renal impairment ; uricosuria ; diuretic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The efficacy of ticrynafen in the treatment of hypertension in patients with moderate renal impairment was compared with that of hydrochlorothiazide in a randomised, double-blind crossover trial in eleven subjects with renal insufficiency. Significant reductions in blood pressure occurred with both treatments, with the maximum responses occurring at different time intervals and to different degrees in individual patients. Thus, although ticrynafen caused a significant reduction in blood pressure in this group of hypertensive patients with renal insufficiency, it was not consistently different from that which could be achieved with hydrochlorothiazide. Ticrynafen also significantly reduced the serum uric acid concentration, compared with a significant rise with hydrochlorothiazide. No major biochemical abnormalities or side-effects were encountered in any subject. Thus, in these patients with renal insufficiency, ticrynafen still demonstrated a uricosuric effect as well as a useful anti-hypertensive action.
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  • 21
    ISSN: 1432-1041
    Keywords: labetalol ; chlorthalidone ; hypertension ; fixed combination ; antihypertensive therapy ; side effects ; multicentre study
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary In a multicentre, double-blind, crossover, placebo-controlled study, the antihypertensive effect of labetalol 100 mg and chlorthalidone 10 mg, given alone or in combination, has been assessed in 32 hypertensive patients. The combination had a greater effect in reducing blood pressure than did its separate components. This was particularly evident after exercise. Heart rate increased during chlorthalidone therapy, decreased during labetalol therapy, and a summation effect was observed during treatment with the combination. In most cases additivity was observed, as no interaction between the single components was observed, except for heart rate after exercise, and for diastolic blood pressure in the upright position. No interaction was observed either in the biochemical indices or in the clinical side-effects.
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  • 22
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    European journal of clinical pharmacology 21 (1982), S. 389-390 
    ISSN: 1432-1041
    Keywords: nifedipine ; metoprolol ; hypertension ; calcium antagonist ; side effects
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary In a double-blind trial 26 patients with essential hypertension were treated with nifedipine or placebo for 8 weeks, following a 4-week run-in place-bo period in all patients. The daily dosage of nifedipine during this phase was 10mg 3 times daily. Metoprolol was then added to the therapeutic regimen of both groups for a further 12 weeks. Both nifedipine and metoprolol used as mono-therapy caused statistically significant reductions of arterial pressure. The addition of metoprolol to nifedipine tended to reduce blood pressure further, but blood pressures were not significantly lower than during nifedipine mono-therapy. Side-effects were few and only two patients had to be withdrawn during active therapy, one for headaches during nifedipine therapy, and another for asthma during metoprolol treatment. Combined therapy with a beta-adrenoceptor blocking agent, such as metoprolol, and a calcium antagonist with vasodilating properties, such as nifedipine, offers a theoretically interesting approach in the treatment of hypertension, even though the practical outcome in the present study probably suffered from an inadequate dose of nifedipine during the period of combined therapy.
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  • 23
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    European journal of clinical pharmacology 22 (1982), S. 95-99 
    ISSN: 1432-1041
    Keywords: penbutolol ; hypertension ; primary hypertension ; blood pressure response ; plasma concentration
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Penbutolol (Hoe 893 d), a long-acting non-selective beta-adrenoceptor blocking agent, was given once daily to 23 patients with primary hypertension, WHO Stages I–II. The dose (50–100 mg) needed to achieve the therapeutic goal, i.e. supine diastolic BP〈95 mm Hg, was titrated individually. On a daily dose of penbutolol 83±19 mg (mean±SD) blood pressure (BP, mean±SD) fell from 180±21/112±8 mmHg on placebo to 154±25/94±14 mmHg. 18 patients who reached the therapeutic goal (responders) continued in a double blind, cross-over study versus placebo, during which the supine BP fell on average 20/10 mmHg on the same dose of penbutolol, and 2/1 mmHg on placebo. Plasma concentrations (mean±SD) of free 0.10±0.07 µg/ml) and total (2.02±1.39 µg/ml) penbutolol did not differ between responders and nonresponders, and were not correlated with the fall in BP. Side effects were mild and mostly well tolerated. One patient developed dermatitis and another an elevation of liver enzymes.
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  • 24
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    European journal of clinical pharmacology 23 (1982), S. 403-409 
    ISSN: 1432-1041
    Keywords: alpha-2-adrenoceptors ; hypertension ; clonidine ; human platelets ; 3H-yohimbine binding ; receptor regulation ; clonidine withdrawal ; desensitization ; GTP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The effect of clonidine on the number ofα 2-adrenoceptors in human platelet membranes, determined by3H-yohimbine binding, was investigatedin vitro andin vivo. Incubation of platelet membranes with clonidine (1–100 µM) for 16 h at 25 °C led to a concentration-dependent decrease in the number of3H-yohimbine binding sites of 10–25%; the affinity of3H-yohimbine to the sites was not changed (KD approximately 3–4 nM). In such “desensitized” membranes, inhibition of3H-yohimbine binding by clonidine resulted in steep, monophasic displacement curves, which in comparison to the curves from control membranes (IC50 for clonidine 90 nM), were shifted to the right (IC50: 321 nM) and were not affected by 10−4M guanosine-5′-triphosphate (GTP). Treatment of 3 hypertensive patients with clonidine (3×150 µg/d for 7 days) reduced blood pressure and heart rate. Simultaneously, both3H-yohimbine binding sites on platelet membranes and plasma catecholamine levels decreased within three days and remained at a reduced level during treatment. After abrupt cessation of clonidine treatment, blood pressure, heart rate and plasma catecholamines rapidly increased, reaching values after two days similar to or higher than those before treatment.3H-yohimbine binding sites, however, initially decreased further before returning to control values. In platelet membranes derived from hypertensive patients treated with clonidine for at least three weeks, GTP (10−4M) had no influence on inhibition of3H-yohimbine binding by (—)-adrenaline and clonidine. It is concluded that clonidine desensitizesα 2-adrenoceptors in human platelet membranesin vitro andin vivo. An important step in the desensitization process is the uncoupling of receptor occupancy by agonists and adenylate cyclase activity, as indicated by loss of the regulatory activity of GTP on desensitized membranes. The clonidine withdrawal syndrome may be caused by enhanced release of endogenous catecholamines not adequately regulated by presynapticα 2-adrenoceptors, which have become subsensitive after chronic clonidine treatment.
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  • 25
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    European journal of clinical pharmacology 23 (1982), S. 491-494 
    ISSN: 1432-1041
    Keywords: betaxolol ; hypertension ; double-blind trial ; cross-over trial
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Betaxolol is a cardioselective beta-blocker, which has a bioavailability of 90% and a T1/2 of 20 h. A four group, cross-over double-blind trial was conducted to select between betaxolol 20 mg and 40 mg for long term trials. 60 patients were allocated randomly to one of the sequences placebo-20 mg, 20 mg-placebo, placebo-40 mg and 40 mg-placebo, each treatment lasting for 2 weeks. Groups were homogenous for baseline diastolic blood pressure (DBP), age and male/female ratio, and were slightly unbalanced for weight. A two-way ANOVA (3 treatments, 2 sequences) showed no treatment-sequence interaction nor sequence effect. The mean reduction in DBP was 14.2±1.8 mm Hg following 20 mg and 18.0±1.8 following 40 mg betaxolol, and 4.0±1.2 mm Hg during placebo (p〈0.001). Age, weight, baseline DBP and duration of hypertension did not influence the treatment effect. The 95% confidence intervals of the reduction in DBP were 10.4–17.9 for 20 mg and 14.3–21.6 mm Hg for betaxolol 40 mg. Aiming at a mean reduction to 90 mm Hg, betaxolol 20 mg would appear to be adequate in similar patient populations.
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  • 26
    ISSN: 1432-1041
    Keywords: prizidilol ; hypertension ; side effects ; chronic treatment ; antihypertensive effect ; anaemia
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The antihypertensive effect of a new vasodilator with betablocking properties (SK & F 92657) was investigated in 10 patients with mild to moderate essential hypertension. After a mean treatment period of 26,5 weeks (6,5–49 weeks) blood pressure was significantly reduced, from 168±22/106±6 mmHg to 144±19/94±12 mmHg (p〈0.05 and 0.025). The mean dose was 410 mg (100–700 mg). Heart rate decreased slightly from 77±12 to 70±8 beats/min. Plasma renin activity and plasma aldosterone showed only minor changes. Nausea, heavy dreams, facial and hand flushing and mild depression were reported as side effects. In most patients the symptoms disappeared without reduction in the dose. In one patient anaemia developed after 7 weeks and treatment with prizidilol was stopped. A slight but statistically significant decrease in haemoglobin concentration of 1.1±0.6 g/dl was observed in 5 of the 10 patients (p〈0.02). Thus, a mean dose of prizidilol of 410±242 mg/day had a mean blood pressure lowering effect of 24/12 mmHg. In 7 of the 10 patients (70%) diastolic blood pressure could be reduced to 95 mmHg or less. However, the observed haematological side-effects should be carefully monitored in further studies and may limit the clinical use of prizidilol.
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  • 27
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    European journal of clinical pharmacology 22 (1982), S. 379-381 
    ISSN: 1432-1041
    Keywords: propranolol ; hypertension ; elderly patients ; long-acting propranolol
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Fifteen elderly patients whose hypertension was controlled by conventional propranolol 80 mg twice a day had their medication changed to one capsule of ‘Inderal’ LA1 (160 mg) daily. The blood pressure, heart rate and propranolol concentrations were measured at various time points when the patients were receiving the conventional preparation and these assessments were repeated when the long-acting preparation was administered. Although the heart rate was lower with conventional propranolol than with ‘Inderal’ LA there was no significant difference in the blood pressure levels. The mean peak blood level of propranolol was, however, significantly lower with ‘Inderal’ LA compared with conventional propranolol and occurred later. At 12 h the plasma propranolol levels were higher after ‘Inderal’ LA than following the intake of conventional propranolol (p〈0.01); there was no difference in the plasma levels at 24 h. The area under the concentration time curve was significantly higher on conventional propranolol. Compared with published data, the plasma levels were higher than those in younger patients. ‘Inderal’ LA was well tolerated and side effects were minimal.
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  • 28
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    European journal of clinical pharmacology 23 (1982), S. 397-401 
    ISSN: 1432-1041
    Keywords: hypertension ; prazosin ; alpha-adrenoceptors ; alpha-blocking drugs ; UK-33,274
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Eleven patients with uncomplicated essential hypertension received increasing single daily doses of UK-33,274, a new alpha-1 adrenoceptor antagonist, and prazosin for 4 days, in a open cross-over study. Doses were increased until a satifactory blood pressure response was obtained. Average doses reached were 4.5 mg for UK-33,274 and 2.4 mg for prazosin. The maximum effect of the two drugs on standing blood pressure was similar, but prazosin was more effective in the supine position. Both drugs had a greater effect on standing than on supine blood pressure. UK-33,274 caused a consistent increase in heart rate while prazosin did not. Whereas there was no clear difference between the two compounds in the duration of the reduction in blood pressure the onset of action was more gradual for UK-33,274. The incidence of side-effects was similar for both drugs. The data suggest that UK-33,274 is less effective than prazosin in reducing blood pressure.
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  • 29
    ISSN: 1432-1041
    Keywords: carprazidil ; minoxidil ; hypertension ; catecholamines ; renin ; aldosterone ; blood volume ; hypertrichosis ; side effects
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    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The efficacy and side effects of the new vasodilator carprazidil and the established vasodilator minoxidil were compared in 18 hypertensive patients inadequately controlled by 2 to 4 conventional drugs; the latter included diuretics, beta-blockers and/or sympatholytics and, in half the cases, vasodilators, such as hydralazine, diazoxide or the postsynaptic alpha-blocker prazosin. The vasodilators were withdrawn and, using a crossover design all patients received carprazidil (mean final dose 88 mg) and minoxidil (20 mg) for an average period of 5 to 6 months. The effects of the 2 agents appeared to be qualitatively and quantitatively similar. Both tended to cause sodium retention and an increase in heart rate, which required an increased dose of diuretic in one third of the cases or of a beta-blocker in a quarter. With this approach mean body weight and blood volume were not altered in the established phase of carprazidil or minoxidil treatment; heart rate and plasma norepinephrine tended to be only minimally increased, plasma renin was slightly increased, and plasma aldosterone and epinephrine were largely unchanged. Supine and upright blood pressure were reduced from initial values of 189/113 and 167/113 mm Hg, to 149/95 and 138/95 mm Hg (−18 and −17%), respectively, during carprazidil, and to 154/95 and 141/96 mm Hg (−17 and −15%) during minoxidil therapy. Hypertrichosis occurred with both agents in almost all patients, and limits their more prolonged use in females. No adverse side effects on haematological parameters, liver or renal function were observed, nor was antinuclear antibody detected. It is concluded that carprazidil and minoxidil are equivalent vasodilator agents in the treatment of severe hypertension, particularly in males.
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  • 30
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    Chromatographia 15 (1982), S. 595-598 
    ISSN: 1612-1112
    Keywords: Liquid chromatography ; High-speed liquid chromatography ; Small-particle LC columns ; Injector bypass ; Column lifetime in LC
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    Topics: Chemistry and Pharmacology
    Notes: Summary In the case of liquid chromatography columns packed with small (3–5 μm) particles and utilized at relatively high flow rates, pressure pulses associated with the sample injection process (caused by a short-duration interruption in mobile phase flow to the column during injection) may result in a reduction of column lifetime. This detrimental effect can be eliminated by the utilization of specially constructed sample injection valves incorporating properly desinged bypass loops. The paper investigates in detail the effect of pressure pulses, describes the criteria and performance of the bypass systems, and documents column life time and performance.
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  • 31
    ISSN: 1573-8221
    Keywords: catecholamines ; hypertension ; hypoxia ; adaptation
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    Topics: Biology , Medicine
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  • 32
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    Bulletin of experimental biology and medicine 94 (1982), S. 1063-1066 
    ISSN: 1573-8221
    Keywords: prostaglandins ; hemodynamics ; baroreflex ; hypotension ; hypertension
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  • 33
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    Chromatographia 15 (1982), S. 83-85 
    ISSN: 1612-1112
    Keywords: Liquid chromatography ; Tricyclic antidepressants ; Solid phase extraction ; Serum ; Clinical analysis
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    Topics: Chemistry and Pharmacology
    Notes: Summary Five common tricyclic antidepressants are separated on a silica column using an aqueous eluent. The tricyclics are concentrated from serum using an adsorption procedure on a solid phase Sep PakTM C18 cartridge. The method appears to be adequate for monitoring therapeutic levels of these drugs.
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  • 34
    ISSN: 1612-1112
    Keywords: Liquid chromatography ; Complex solvent mixtures ; Optimization of solvent composition
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    Topics: Chemistry and Pharmacology
    Notes: Summary Four different methods of calculation of retention in ternary mobile phases were compared and it was found that the simple calculation based only on two values of the capacity factors (one for each binary system that composes the ternary mobile phase) provides the accuracy of prediction that is, at least, comparable to the other methods of calculation that require a large number of preliminary experiments. The deviations from ideal behaviour in ternary solvent mixtures are discussed; some sources of errors can be avoided, at least partially, using binary systems of adequate compositions for preparation of ternary mobile phases. Several examples show the comparison of calculated and experimental selectivities in ternary solvent systems. A simple calculation can be used for rapid selection of an adequate ternary (or more complex) mobile phase, if it is necessary to achieve the separation of a given sample mixture.
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  • 35
    ISSN: 1612-1112
    Keywords: Liquid chromatography ; Reverse-phase ; 3 μm packing materials
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    Topics: Chemistry and Pharmacology
    Notes: Summary The efficiency of high-performance liquid chromatography columns packed with 5 μm and 3 μm reverse-phase octadecylsilane packing materials has been evaluated using four test mixtures. Both stopped flow and valve injection have been used and typical efficiencies are given.
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  • 36
    ISSN: 1612-1112
    Keywords: Phosphorescence, room-temperature ; Detection, continuous flow ; Liquid chromatography ; Halogenated componds ; Dibenzofurans
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    Topics: Chemistry and Pharmacology
    Notes: Summary It is shown that sensitized room-temperature phosphorescence in liquid solutions can be successfully applied as a detection method in continuous flow and chromatographic systems. The limits of detection for a series of halogenated naphthalenes and biphenyls obtained by plug injection are roughly the same as those in batch experiments — in the subnanogram region. Liquid chromatograms of mixtures of PCBs, PCNs and polychlorodibenzofurans are given.
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  • 37
    ISSN: 1612-1112
    Keywords: Liquid chromatography ; Chlorophenols in water ; Preconcentration ; Post-column photochemical dechlorination ; Electrochemical, UV and fluorescence detection ; Column switching
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    Topics: Chemistry and Pharmacology
    Notes: Summary A specific HPLC method has been developed for the trace analysis of lower chlorinated aromatic compounds. The method consists of an on-line preconcentration and a post-column reaction step. On-line preconcentration of mono- and dichlorophenols from aqueous samples has been performed using PRP1, a divinylbenzene-styrene copolymeric sorbent as packing material for both pre-and analytical column. Enrichment factors of over 300 were obtained compared to regular (100 μl) loop injections, even for the highly polar monochlorophenols. After reversed-phase separation, post-column photochemical dechlorination is carried out directly in the eluent stream, using a photochemical reactor. Upon dechlorination, fluorescent products are formed, which can be detected selectively. The resulting fluorescence signal shows a linear response to the quantity of solute present over 2 to 3 orders of magnitude (correlation coefficients: 0.990–0.98). For the mono- and dichlorophenols, the detection limit of the photoconversion method is in the lower nanogram range. The method is especially suitable for the analysis of complex matrices such as effluent water samples or biological fluids containing traces of the polar chloroaromatic compounds together with large amounts of other constituents, which interfere when using more general methods of detection like UV absorption. The potential of this technique for automation has been demonstrated by using a microprocessor-controlled column switching unit.
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  • 38
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    Chromatographia 15 (1982), S. 437-444 
    ISSN: 1612-1112
    Keywords: Detection ; Liquid chromatography ; Reversed phase ; Ion-pairing probes
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    Topics: Chemistry and Pharmacology
    Notes: Summary Compounds without own detector response can be detected and quantified by a UV-absorbing or fluorescent, ion-pairing probe in reversed-phase liquid-solid systems. Charged as well as uncharged samples give response by affecting the distribution of the probe between the phases. The probe is usually a hydrophobic organic ion. It is included in the mobile phase, which also contains a counter ion and an ion of the same charge as the probe, both fairly hydrophilic. The choice of properties and concentrations of the hydrophilic ions is essential for the response since too low and too high distribution of the mobile phase ions to the adsorbent will make the system insensitive. It is with UV-absorbing probes possible to get a response corresponding to a molar absorptivity of more than 3000 for ionic samples. Fluorescent probes have given 3–5 times higher sensitivity. Uncharged compounds give as a rule lower response. A combination of two UV-absorbing probes with different charge gives a considerable improvement of the response for samples with low retention. A simplified theoretical model for the detector response is suggested on the basis of detailed studies of the concentration changes in the eluted mobile phase.
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  • 39
    ISSN: 1612-1112
    Keywords: Liquid chromatography ; Photochemical reaction detection ; Chemical post-column reduction ; Fluorimetric detection ; Air segmented flow systems ; Non-aqueous reversed-phase chromatography
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    Topics: Chemistry and Pharmacology
    Notes: Summary A new photochemical reaction method for the on-line fluorimetric detection of natural vitamin K homologs was developed. In addition to its high sensitivity, the method features an interesting selectivity for the determination of these compounds in a complex matrix such as human serum. The formation of different photolysis products as a function of reaction conditions, and the optimalisation of a segmented flow reaction system will be discussed. The results indicate that the method is 4 times more sensitive than UV detection, and at least as selective as fluorescence detection after post-column chemical reduction.
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  • 40
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    Chromatographia 15 (1982), S. 476-478 
    ISSN: 1612-1112
    Keywords: Liquid chromatography ; Mass detector ; Carbohydrates ; Lipids
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    Topics: Chemistry and Pharmacology
    Notes: Summary The mass detector was investigated as an alternative to RI detection for carbohydrate and lipid analyses with high pressure liquid chromatography. The instrument was found to be more sensitive than most RI detectors and, as gradient elution could also be carried out, the resulting chromatograms showed improved resolution.
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  • 41
    ISSN: 1612-1112
    Keywords: Liquid chromatography ; Nucleobases ; Nucleosides ; Silica gel
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    Topics: Chemistry and Pharmacology
    Notes: Summary The retention behaviour of nucleobases and nucleosides on unmodified silica with dichloromethane-methanol-water mixtures has been systematically investigated. The degree and order of retention can be varied over a wide range by changing the pH, the type and concentration of the acidic additives and by the methanol and water content of the mobile phase. The retention process cannot be considered as simple adsorption but rather as a very complex mixed distribution process of adsorption and absorption including the involvement of ion-pair formation. Further data on the effect of the type of silica (source of supply) on retention behaviour, column efficiency and column reproducibility are reported. The practical application of unmodified silica for the separation of nucleobases and nucleosides is demonstrated by the analysis of a hydrolysate of calf thymus DNA.
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  • 42
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    Chromatographia 15 (1982), S. 403-408 
    ISSN: 1612-1112
    Keywords: Liquid chromatography ; Reaction detector ; Colorimetric detection
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    Topics: Chemistry and Pharmacology
    Notes: Summary A reaction detector with non-segmented flow in open tubes as reaction track is described. To minimize peak broadening the open tubes are arranged in a three dimensional coiled structure by knitting. At low volume flow rates the h-values in these open tubes are independent of flow rate and are significantly lower than predicted by theory. The applicability of this reactor for classical colorimetric detection with corrosive reagents is shown.
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  • 43
    ISSN: 1612-1112
    Keywords: Liquid chromatography ; Ultra-violet detection ; Temperature effects
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    Topics: Chemistry and Pharmacology
    Notes: Summary This paper is concerned with our investigation into the effects of temperature on the liquid chromatography absorbance baseline. Measurements were made to quantify the effects in terms of wavelength and solvents. Five solvents commonly used in HPLC were investigated, methanol, propanol, hexane, heptane and acetonitrile. The alcoholic solvents were found to have a high absorbance sensitivity to temperature at wavelengths around their ‘UV cut off’ points. Possible mechanisms for this effect are discussed and include solvent impurity, density changes and inter-molecular bonding.
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  • 44
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    Chromatographia 16 (1982), S. 18-25 
    ISSN: 1612-1112
    Keywords: Gaschromatography ; Liquid chromatography ; Open tubular columns ; Capillary columns ; History of chromatography
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    Topics: Chemistry and Pharmacology
    Notes: Summary The paper presents an overview of the evolution of open tubular (capillary) columns introduced 25 years ago by M.J.E. Golay. This evolution is divided into five stages: the formulation of the theory and the basic work laying down the foundations for future work; learning the influence of the variables on column performance; development of columns with increased surface area; development of glass and fused-silica columns; and, finally, the introduction of open tubular columns in liquid chromatography. In each stage, the pioneering activities are summarized and the most important references given.
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  • 45
    ISSN: 1612-1112
    Keywords: Liquid chromatography ; Derivatization with NBD-F ; Amino acids, biogenic amines ; Blood analysis
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    Topics: Chemistry and Pharmacology
    Notes: Summary The reaction of a newly developed fluoregenic reagent, 7-fluoro-4-nitrobenzo-2-oxa-1,3-diazole(NBD-F), with amino acids and biogenic amines was investigated. NBD-F was reactive to both primary and secondary amines including amino acids and biogenic amines such as catecholamines. The amino acids were reacted with the reagent, separated by high-performance liquid chromatography on μ-Bondapak C18 and detected at 10 to 100 fmol level. A few μg of protein hydrolysates, rabbit pyruvate kinase M1, rabbit aldolase A and papain, were adequate for the amino acids quantitation. An automatic amino acid analyzer with fluorometric detection by the post-column derivatization with NBD-F enabled the amino acid profile analysis in blood samples present in a paper disc of 3 mm diameter.
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  • 46
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    Chromatographia 16 (1982), S. 216-218 
    ISSN: 1612-1112
    Keywords: Liquid chromatography ; Size exclusion ; Biological extracts ; Allergens
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    Topics: Chemistry and Pharmacology
    Notes: Summary Extracts of insect, mite, fungal and mammalian origin, known to provoke an allergic response in man, have been examined and fractionated by high-performance size exclusion chromatography. The mild conditions employed for separation have permitted direct immunological assessment of the fractions obtained, and recognition of the biologically important components. These are being isolated for further study. This chromatographic procedure has proved to be of value for assessing different extracts from the same source material as potential reference preparations. It can also be employed as a sensitive method for identification of extracts derived from a variety of sources.
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  • 47
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    Chromatographia 16 (1982), S. 224-227 
    ISSN: 1612-1112
    Keywords: Liquid chromatography ; Chiral bonded phases ; Aminoacid racement resolution
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    Topics: Chemistry and Pharmacology
    Notes: Summary N-Protected aminoacids have been chemically bonded to aminopropylated silica gel, and the resulting chiral phases have been applied to the LG resolution of racemic mixtures of polar compounds. Best results were obtained with surfacebound N-formyl-isoleucine and N-formylvaline, with which baseline resolutions of a range of aminoacid and aminoalcohol derivatives were achieved.
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  • 48
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    Chromatographia 16 (1982), S. 237-241 
    ISSN: 1612-1112
    Keywords: Liquid chromatography ; Electron capture detection ; Improved interface
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    Topics: Chemistry and Pharmacology
    Notes: Summary An improved interface for the coupling of a liquid chromatograph (LC) and an electron-capture detector (ECD) allows the use of the LC-ECD combination for the determination of various types of chlorinated aromatic compounds. The addition of up to 6% of dioxan to the hexane used as mobile phase can be tolerated without serious deterioration of detector performance. Derivatization of polar compounds such as anilines, phenylurea herbicides, chlorophenols and hydroxylated polychlorobiphenyls with fluorine-and non-fluorine-containing acid anhydrides is a useful tool to extend the application range of LC-ECD. As an example, the analysis of a spiked soil sample is discussed.
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  • 49
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    Chromatographia 16 (1982), S. 265-266 
    ISSN: 1612-1112
    Keywords: Liquid chromatography ; Short micro bore columns ; Small volume electrochemical detector
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    Topics: Chemistry and Pharmacology
    Notes: Summary A flow-through two electrode wall-jet cell with a platinum measuring electrode and a cell volume of 20 nl has been designed and evaluated. It has been used to detect phenols by reversed phase liquid chromatography using short micro bore columns. The linear dynamic range between the measured current and the concentration is greater than 103 (1.5×10−7−5×10−4 mol/l) and the minimum analyzable amount was found to be 10 pg for pyrocatechol. A negligible broadening in the detector permits the use of micro columns down to 0.5 mm internal diameter, packed with 5 μm particles, without any substantial distortion of eluted zones.
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  • 50
    ISSN: 1612-1112
    Keywords: Liquid chromatography ; Chemically bonded silica ; Hydrolytically stable ; Metal complexing ligands ; Amino acid separation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A silica of 14 nm pore size was reacted according to two procedures with the following silanes: γ-aminopropyltriethoxysilane (1), N-aminoethyl-N′-aminopropyltrimethoxysilane (2), N-aminoethyl-N′-aminoethyl-N″-aminopropyltrimethoxysilane (3), N-(3-triethoxysilanepropyl)-N, N-diacetic dimethylester (4), N-(3-trisodiumsilanolatepropyl)-N, N-diacetic acid disodium salt (5) and N-(3-trisodiumsilanolatepropyl)-ethylenediamine-N, N′, N′-triacetic acid trisodium salt (6). The reaction of silanes 1–4 with the silica was carried out under anhydrous conditions (procedure A). Silanes 1–6 were subjected to surface modification under essentially hydrous conditions applying a two-step procedure (procedure B). Procedure B is much simpler to perform and allows binding of high and definite amounts of silane onto the surface. Complexation of all bonded phases with Cu2+ was examined by measuring the sorption isotherms at constant pH. The pH-dependence of Cu2+ uptake at constant Cu2+ concentration was evaluated. Tests on the chemical and chromatographic stability of the packings showed that only the silicas with bonded iminodiacetate and ethylenediaminetriacetate groups remain hydrolytically stable. Retention of aliphatic and α-amino acids on these two packings was found to be mainly controlled by the pH and the ionic strength of the eluent.
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  • 51
    ISSN: 1612-1112
    Keywords: Liquid chromatography ; Multiphase eluents ; Biopolymers ; Microorganisms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A novel form of liquid chromatography is described which involves the use of multiphase eluents, such as emulsions, for the separation of biopolymers and certain microorganisms.
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  • 52
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    Chromatographia 16 (1982), S. 368-371 
    ISSN: 1612-1112
    Keywords: Liquid chromatography ; Hydrated silica gel ; Nonpolar and polar eluents ; Elevated column temperatures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The effect of nonpolar (hexane, decane, benzene) and polar (water, isopropanol, water+isopropanol) eluents on separation of aromatic hydrocarbons and their derivatives in liquid-adsorption chromatography on hydroxylated silica gel columns has been studied. The work has revealed that the traditional application areas of hydroxylated silica gel in liquid chromatography may be extended. In particular it has been shown that, first, polar compounds may be separated on hydroxylated silica gel with nonpolar eluents at high temperatures (100–150°C) and that polar and nonpolar compounds may be separated using pure water as eluent. The effect of adsorbed moisture on retention behaviour of silica gel with nonpolar eluents has also been investigated.
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  • 53
    ISSN: 1612-1112
    Keywords: Liquid chromatography ; Terbium determination ; Trace element analysis ; Gadolinium oxide sulphide ; Luminescent phosphors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A detailed study of isocratic and gradient elution separations of lanthanides has been carried out. Analyses of industrially and scientifically interesting products such as luminescent phosphors have been carried out by gradient elution with DL-2-hydroxyisobutyric acid. The determination of small amounts of terbium in gadolinium oxide sulphide phosphors is described in which an HCl solution was eluted through a stainless steel column packed with microparticulate silica, with bonded cation-exchange groups. Complete separation of gadolinium and terbium is achieved. Detection is with a variable wavelength detector following post-column complex formation with 4-(2-pyridylazo)-resorcinol monosodium salt. Results obtained on test solutions show good reproducibility and sensitivity and the method may be considered sufficiently reliable to be used in routine quality control procedures.
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  • 54
    ISSN: 1612-1112
    Keywords: Liquid chromatography ; Carbohydrates ; Bonded-phase columns ; Silica gel modified with amino groups
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary For the separation of carbohydrates by liquid chromatography, utilizing the intermolecular interaction with amino groups on the surface of the adsorbent, two types of adsorbents were used: silica gel modified by adding to the eluent a diamine, and a chemically bonded phase prepared by the reaction of γ-aminopropyl triethoxy silane with silica gel. Mono- di- and trisaccharides could be separated on silica gel modified by the adsorption of piperazin and ethylene diamine from the eluent. The separation capacity of columns packed with silica gel with bonded NH2 groups and with silica gel having diamines adsorbed on its surface is similar. The retention volumes of 15 carbohydrates were measured on columns containing silica gel with hydroxylated surface and on silica gel modified with piperazin from the eluent consisting of acetone-water. Comparison of acetone-water and acetonitrile-water as the eluent showed that the former is also suitable for the analysis of carbohydrates.
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  • 55
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    Chromatographia 15 (1982), S. 161-166 
    ISSN: 1612-1112
    Keywords: Reaction detectors ; Liquid chromatography ; Pharmaceutical analysis ; Environmental analysis ; Trace organics analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Reaction detectors are considerably enhancing the application potential of HPLC particularly when dealing with trace analysis in complex matrices. In principle one distinguishes between segmented and non-segmented reactor system. The theory of band broadening of these designs and some criteria for the choice of the proper type are brieffly discussed. It seems that with a proper construction of the phase separators segmented systems have a wider range of applicability. Applications of reaction detectors in the areas of pharmaceutical and environmental analysis are discussed.
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  • 56
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    Chromatographia 15 (1982), S. 277-281 
    ISSN: 1612-1112
    Keywords: Liquid chromatography ; Solvent selectivity ; Steroids ; Amine bonded phase ; Overlapping resolution mapping
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Resolution (Rs) is a function of three factors: efficiency, retentivity and selectivity. A procedure for optimization of mobile phase selectivity was demonstrated using a reversed-phase (RP) separation of compounds with various functionalities. In this paper, the same procedure is used with normal bonded-phase (NP) chromatography to develop a separation of structurally similar steroids. The optimization of mobile-phase selectivity provided increased problem-solving capability and decreased the analysis time.
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  • 57
    ISSN: 1612-1112
    Keywords: Liquid chromatography ; Dilution and signal enhancement factor ; Maximum injection volume ; Calculation methods ; HPLC small volume columns
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The responding signals of eluted components can be enhanced by using high performance small volume columns with long lengths generating more plates than required for a separation with a preset resolution in combination with instruments which show very small external bandbroadening. The excess number of plates is then consequently erased by maximizing the injection volume of the sample until the preset resolution is reached. Equations, describing the dilution, relative signal enhancement and maximum injection volume as a function of the process parameters are derived and experimentally verified. Theory and experiment are in agreement only if variances of response functions are calculated as their second normalized central moments.
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