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  • 1
    Digitale Medien
    Digitale Medien
    Immunohistochemical localization of cytochrome P450 3A in human pulmonary carcinomas and normal bronchial tissue (1995)
    Springer
    Histochemistry and cell biology 103 (1995), S. 25-29 
    Details
    ISSN: 1432-119X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract The cytochrome P450 (CYP) enzymes metabolize drugs and other xenobiotics in liver and also in some extrahepatic tissues. We have studied the expression and localization of CYP3A in primary lung tumours and normal lung tissue from the same patients. Thirtytwo patients undergoing partial or total lung resection for therapy of primary pulmonary carcinoma were included in this study. Immunohistochemical staining for CYP3A was performed with a modification of the ABC technique. Eight of the 32 cases of primary pulmonary carcinoma showed expression of CYP3A. In 12 of the 32 cases of normal tissue, the seromucous glands were positive for CYP3A. The bronchial epithelium was positive for CYP3A in 11 cases. We observed no correlation between CYP3A expression in tumour tissue and that in seromucous glands or bronchial epithelium. We conclude that CYP3A is present in both normal and cancerous lung tissue. Our findings suggest, however, no co-expression of CYP3A in lung cancer.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01464472
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  • 2
    Digitale Medien
    Digitale Medien
    Effect of magnesium hydroxide on the absorption and efficacy of tolbutamide and chlorpropamide (1992)
    Springer
    European journal of clinical pharmacology 42 (1992), S. 675-679 
    Details
    ISSN: 1432-1041
    Schlagwort(e): Tolbutamide ; Magnesium hydroxide ; chlorpropamide ; gastrointestinal absorption ; drug interaction ; healthy volunteers ; plasma glucose ; plasma insulin
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The effect of magnesium hydroxide on the absorption and efficacy of tolbutamide and chlorpropamide was examined in a total of 32 healthy volunteers in two separate, randomized parallel-group studies, with 16 subjects in each study. After an overnight fast, the first group of 8 volunteers ingested 500 mg tolbutamide or 250 mg chlorpropamide with 150 ml water, and the second group the same doses of the active drugs with 150 ml water containing 850 mg magnesium hydroxide. Magnesium hydroxide increased the area under the plasma tolbutamide concentration-time curve (AUC) from 0 to 1 h and from 0 to 2 h by 5-fold and 2.5-fold, respectively. The peak plasma concentration, peak time and total AUC were not significantly altered. The incremental insulin area and the decremental glucose area from 0 to 1.5 h were significantly larger in the magnesium hydroxide group than in the controls. The maximum insulin response to tolbutamide was increased fourfold by coadministration of magnesium hydroxide, and it occurred about 1 h earlier than in the control group. In addition, the maximum fall in plasma glucose concentration was attained about 1 h earlier in the antacid group. A tendency to an increased rate of chlorpropamide absorption was observed after magnesium hydroxide, but it did not appear to affect the insulin and glucose responses to chlorpropamide. It is concluded that magnesium hydroxide increased the early bioavailability of tolbutamide, resulting in enhanced insulin and glucose responses. A tendency toward accelerated chlorpropamide absorption by magnesium hydroxide was also observed, but the efficacy of chlorpropamide was unaffected.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00265936
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  • 3
    Digitale Medien
    Digitale Medien
    Grapefruit juice can increase the plasma concentrations of oral methylprednisolone (2000)
    Springer
    European journal of clinical pharmacology 56 (2000), S. 489-493 
    Details
    ISSN: 1432-1041
    Schlagwort(e): Key words Methylprednisolone ; Grapefruit juice ; Interaction
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract Objective: To investigate whether the pharmacokinetics of orally administered methylprednisolone and plasma cortisol concentrations are affected by administration of grapefruit juice. Methods: In a randomised, two-phase, cross-over study, ten healthy subjects received either 200 ml double-strength grapefruit juice or water three times a day for 2 days. On day 3, 16 mg methylprednisolone was given orally with 200 ml grapefruit juice or water. Additionally, 200 ml grapefruit juice or water was ingested 0.5 h and 1.5 h after methylprednisolone administration. Plasma concentrations of methylprednisolone and cortisol were determined using liquid chromatography/mass spectrometry (LC/MS/MS) over a 47-h period. Results: Grapefruit juice increased the total area under the plasma methylprednisolone concentration–time curve (AUC0–∞) by 75% (P 〈 0.001) and the elimination half-life (t 1/2) of methylprednisolone by 35% (P 〈 0.001). The peak plasma concentration of methylprednisolone (Cmax) was increased by 27% (P 〈 0.01). Grapefruit juice delayed the time to the Cmax from 2.0 h to 3.0 h (P 〈 0.05). There was no significant difference in the plasma cortisol concentrations, measured after methylprednisolone administration, between the water and grapefruit juice phases. However, grapefruit juice slightly decreased the morning plasma cortisol concentrations before methylprednisolone administration (P 〈 0.05). Conclusions: Grapefruit juice given in high amounts moderately increases the AUC0–∞ and t 1/2 of oral methylprednisolone. The increase in t 1/2 suggests that grapefruit juice can affect the systemic methylprednisolone metabolism. The clinical significance of the grapefruit juice–methylprednisolone interaction is small, but in some sensitive subjects high doses of grapefruit juice might enhance the effects of oral methylprednisolone.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002280000171
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  • 4
    Digitale Medien
    Digitale Medien
    Effect of fluconazole on plasma fluvastatin and pravastatin concentrations (2000)
    Springer
    European journal of clinical pharmacology 56 (2000), S. 225-229 
    Details
    ISSN: 1432-1041
    Schlagwort(e): Key words Fluvastatin ; Pravastatin ; Fluconazole
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract Objective: To study the effects of fluconazole on the pharmacokinetics of fluvastatin and pravastatin, two inhibitors of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase. Methods: Two separate randomised, double-blind, two-phase, crossover studies with identical study design were carried out. In each study, 12 healthy volunteers were given a 4-day pretreatment with oral fluconazole (400 mg on day 1 and 200 mg on days 2–4) or placebo, according to a randomisation schedule. On day 4, a single oral dose of 40 mg fluvastatin (study I) or 40 mg pravastatin (study II) was administered orally. Plasma concentrations of fluvastatin, pravastatin and fluconazole were measured over 24 h. Results: In study I, fluconazole increased the mean area under the plasma fluvastatin concentration–time curve (AUC0–∞) by 84% (P 〈 0.01), the mean elimination half-life (t 1/2) of fluvastatin by 80% (P 〈 0.01) and its mean peak plasma concentration (Cmax) by 44% (P 〈 0.05). In study II, fluconazole had no significant effect on the pharmacokinetics of pravastatin. Conclusions: Fluconazole has a significant interaction with fluvastatin. The mechanism of the increased plasma concentrations and prolonged elimination of fluvastatin is probably inhibition of the CYP2C9-mediated metabolism of fluvastatin by fluconazole. Care should be taken if fluconazole or other potent inhibitors of CYP2C9 are prescribed to patients using fluvastatin. However, pravastatin is not susceptible to interactions with fluconazole or other potent CYP2C9 inhibitors.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002280000127
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  • 5
    Digitale Medien
    Digitale Medien
    The area under the plasma concentration–time curve for oral midazolam is 400-fold larger during treatment with itraconazole than with rifampicin (1998)
    Springer
    European journal of clinical pharmacology 54 (1998), S. 53-58 
    Details
    ISSN: 1432-1041
    Schlagwort(e): Key words Midazolam ; Itraconazole ; Rifampicin
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract Objective: To determine the effects of treatment with itraconazole and rifampicin (rifampin) on the pharmacokinetics and pharmacodynamics of oral midazolam during and 4 days after the end of the treatment. Methods: Nine healthy volunteers received itraconazole (200 mg daily) for 4 days and, 2 weeks later, rifampicin (600 mg daily) for 5 days. In addition, they ingested 15 mg midazolam before the first treatment, 7.5 mg on␣the␣last day of itraconazole administration, and 4 days␣later,␣and 15 mg 1 day and 4 days after the last dose␣of␣rifampicin.␣The disposition of midazolam and its α-hydroxy metabolite was determined and its pharmacodynamic effects were measured. Results: During itraconazole treatment, or 4 days after, α-hydroxymetabolite the dose-corrected area under the plasma midazolam concentration–time curve (AUC0–∞) was 8- or 2.6-fold larger than that before itraconazole (i.e. 1707 or 695 versus 277 ng · h · ml−1), respectively. One day after rifampicin treatment, the AUC0–∞ of midazolam was 2.3% (i.e. 4.4 ng · h · ml−1) of the before-treatment value and only 0.26% of its value during itraconazole treatment; 4 days after rifampicin, the AUC0–∞ was still only 13% (i.e. 27.1 ng · h · ml−1) of the before-treatment value. The peak concentration and elimination half-life of midazolam were also increased by itraconazole and decreased by rifampicin. The ratio of plasma α-hydroxymidazolam to midazolam was greatly decreased by itraconazole and increased by rifampicin. In addition, the effects of midazolam were greater during itraconazole and smaller 1 day after rifampicin than without treatment. Conclusion: Switching from inhibition to induction of cytochrome P450 3A (CYP3A) enzymes causes a very great (400-fold) change in the AUC of oral midazolam. During oral administration of CYP3A substrates that undergo extensive first-pass metabolism, similar changes in pharmacokinetics are expected to occur when potent inhibitors or inducers of CYP3A are added to the treatment. After cessation of treatment with itraconazole or rifampicin, the risk of significant interaction continues up to at least 4 days, probably even longer.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002280050420
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  • 6
    Digitale Medien
    Digitale Medien
    Effect of itraconazole on the pharmacokinetics and pharmacodynamics of zolpidem (1998)
    Springer
    European journal of clinical pharmacology 54 (1998), S. 163-166 
    Details
    ISSN: 1432-1041
    Schlagwort(e): Key words Zolpidem ; Itraconazole
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract Objective: Zolpidem is a short-acting␣imidazopyridine hypnotic which is biotransformed in humans mainly by CYP3A4. Itraconazole strongly interacts with many substrates of CYP3A4 such as midazolam and triazolam. In this study, the effect of itraconazole on the pharmacokinetics and pharmacodynamics of zolpidem was investigated to uncover a possible clinically significant interaction. Methods: In a randomized cross-over study with two phases, ten healthy volunteers took either 200 mg itraconazole or placebo once daily for 4 days. A single oral dose of 10 mg zolpidem was given on day 4. Plasma drug concentrations were measured up to 17 h and effects of zolpidem up to 9 h after the ingestion of zolpidem. Results: Itraconazole had no marked effects on the pharmacokinetics of zolpidem; the total area under the plasma zolpidem concentration–time curve (AUC0–∞) was 34% larger during the itraconazole phase (759 ng · h · ml−1) than during the placebo phase (567 ng · h · ml−1). Exophoria of the eyes by the Maddox wing test was significantly increased by itraconazole, but the results of the digit symbol substitution test, critical flicker fusion test, postural sway tests and the visual analogue scale tests for subjective drowsiness and overall drug effect did not differ between the phases. Conclusion: The pharmacokinetics and pharmacodynamics of zolpidem were not remarkably affected by itraconazole in healthy volunteers. Therefore, unlike triazolam, for example, zolpidem can be used in normal or nearly normal doses together with itraconazole and probably also with other CYP3A4 inhibitors.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002280050439
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  • 7
    Digitale Medien
    Digitale Medien
    The effect of fluvoxamine on the pharmacokinetics and pharmacodynamics of buspirone (1998)
    Springer
    European journal of clinical pharmacology 54 (1998), S. 761-766 
    Details
    ISSN: 1432-1041
    Schlagwort(e): Key words Buspiron ; Fluvoxamine ; Interaction
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract Objective: The effects of fluvoxamine, a selective serotonin (5-HT) reuptake inhibitor antidepressant, on the pharmacokinetics and pharmacodynamics of buspirone, a non-benzodiazepine anxiolytic agent, were investigated. Methods: In a randomized, placebo-controlled, two-phase cross-over study, ten healthy volunteers took either 100 mg fluvoxamine or matched placebo orally once daily for 5 days. On day 6, 10 mg buspirone was taken orally. Plasma concentrations of buspirone and its active metabolite, 1-(2-pyrimidinyl)-piperazine (1-PP), were measured up to 18 h and the pharmacodynamic effects of buspirone up to 8 h. Results: The total area under the plasma buspirone concentration-time curve was increased 2.4-fold (P 〈 0.05) and the peak plasma buspirone concentration 2.0-fold (P 〈 0.05) by fluvoxamine, compared with placebo. The half-life of buspirone was not affected. The ratio of the total area under the plasma concentration-time curve of 1-PP to that of buspirone was decreased from 7.4 [6.3 (SD)] to 4.4 (3.6) by fluvoxamine (P 〈 0.05). The results of the six pharmacodynamic tests remained unchanged. Conclusion: Fluvoxamine moderately increased plasma buspirone concentrations and decreased the production of the active 1-PP metabolite of buspirone. The mechanism of this interaction is probably inhibition of the CYP3A4-mediated first-pass metabolism of buspirone by fluvoxamine. However, this pharmacokinetic interaction was not associated with impairment of psychomotor performance and it is probably of limited clinical significance.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002280050548
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  • 8
    Digitale Medien
    Digitale Medien
    Efficacy of activated charcoal versus gastric lavage half an hour after ingestion of moclobemide, temazepam, and verapamil (2000)
    Springer
    European journal of clinical pharmacology 56 (2000), S. 285-288 
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    ISSN: 1432-1041
    Schlagwort(e): Key words Absorption ; Activated charcoal ; Gastric lavage
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract Objective: To compare the efficacy of activated charcoal and gastric lavage in preventing the absorption of moclobemide, temazepam, and verapamil 30 min after drug ingestion. Methods: In this randomized cross-over study with three phases, nine healthy volunteers received a single oral dose of 150 mg moclobemide, 10 mg temazepam, and 80 mg verapamil after an overnight fast. Thirty minutes later, they were assigned to one of the following treatments: 25 g activated charcoal as a suspension in 200 ml water, gastric lavage (10 × 200 ml), or 200 ml water (control). Plasma concentrations of moclobemide, temazepam, and verapamil were determined up to 24 h. Results: Activated charcoal reduced the area under the plasma concentration–time curve from 0 h to 24 h (AUC0–24 h) of moclobemide and temazepam by 55% (P 〈 0.05) and by 45% (P 〈 0.05), respectively. The AUC0–24 h of verapamil was not significantly reduced by charcoal. Gastric lavage decreased the AUC0–24 h of moclobemide by 44% (P 〈 0.05), but had no significant effect on that of temazepam or verapamil. The peak plasma concentration (Cmax) of moclobemide, temazepam, and verapamil was reduced by 40%, 29% (P 〈 0.05), and 16%, respectively, by activated charcoal. Gastric lavage did not significantly decrease the Cmax of any of these drugs. Conclusion: The absorption of moclobemide, temazepam, and verapamil can be moderately reduced by activated charcoal given 30 min after drug ingestion, while gastric lavage seems to be less effective.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002280000139
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  • 9
    Digitale Medien
    Digitale Medien
    Effect of grapefruit juice dose on grapefruit juice–triazolam interaction: repeated consumption prolongs triazolam half-life (2000)
    Springer
    European journal of clinical pharmacology 56 (2000), S. 411-415 
    Details
    ISSN: 1432-1041
    Schlagwort(e): Key words Grapefruit juice ; Triazolam ; Interaction
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract Objective: Grapefruit juice inhibits CYP3A4-mediated metabolism of several drugs during first pass. In this study, the effect of grapefruit juice dose on the extent of grapefruit juice–triazolam interaction was investigated. Methods: In a randomised, four-phase, crossover study, 12 healthy volunteers received 0.25 mg triazolam with water, with 200 ml normal-strength or double-strength grapefruit juice or, on the third day of multiple-dose [three times daily (t.i.d.)] administration of double-strength grapefruit juice. Timed blood samples were collected up to 23 h after dosing, and the effects of triazolam were measured with four psychomotor tests up to 10 h after dosing. Results: The area under the plasma triazolam concentration–time curve (AUC0–∞) was increased by 53% (P 〈 0.01), 49% (P 〈 0.01) and 143% (P 〈 0.001) by a single dose of normal-strength, a single dose of double-strength and multiple-dose administration of double-strength grapefruit juice, respectively. The peak plasma concentration (Cmax) of triazolam was increased by about 40% by a single dose of normal-strength grapefruit juice (P 〈 0.01) and multiple-dose grapefruit juice (P 〈 0.01) and by 25% by a single dose of double-strength grapefruit juice (P 〈 0.05). The elimination half-life (t 1/2) of triazolam was prolonged by 54% during the multiple-dose grapefruit juice phase (P 〈 0.001). A significant increase in the pharmacodynamic effects of triazolam was seen during the multiple-dose grapefruit juice phase in the digit symbol substitution test (DSST, P 〈 0.05), in subjective overall drug effect (P 〈 0.05) and in subjective drowsiness (P 〈 0.05). Conclusions: Even one glass of grapefruit juice increases plasma triazolam concentrations, but repeated consumption of grapefruit juice produces a significantly greater increase in triazolam concentrations than one glass of juice. Thet 1/2 of triazolam is prolonged by repeated consumption of grapefruit juice, probably due to inhibition of hepatic CYP3A4 activity.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002280000156
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  • 10
    Digitale Medien
    Digitale Medien
    Pharmacokinetics and pharmacodynamics of transdermal dexmedetomidine (1994)
    Springer
    European journal of clinical pharmacology 46 (1994), S. 345-349 
    Details
    ISSN: 1432-1041
    Schlagwort(e): Dexmedetomidine ; transdermal ; pharmacokinetics ; α2-adrenoceptor agonist
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract Dexmedetomidine is a novel α2-adrenoceptor agonist that may provide beneficial effects as premedication for anesthesia. The pharmacokinetics and pharmacodynamics of transdermal (TD) and intravenous (IV) dexmedetomidine were studied in nine healthy male subjects in a crossover trial. The TD preparation, containing 625 μg of dexmedetomidine base, was applied on the forehead and left in place for 12 h. The IV dose (2.0 μg·kg-1 as dexmedetomidine hydrochloride) was administered as an infusion over 5 min. Dose-normalized total AUC values were used to calculate dexmedetomidine bioavailability. The bioavailability of dexmedetomidine from the TD preparation was 51%. However, the bioavailability of dexmedetomidine released from the preparation was 88%. The mean terminal half-life was 3.1 h after IV and 5.6 h after TD administration. After TD administration, the mean maximal reductions in blood pressure (systolic/diastolic) and heart rate were 28/20 mmHg and 19 beats·min-1. A sedative effect was obvious within 5 min and 1–2 h after IV and TD administration, respectively.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00194403
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