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  • protein binding
  • Springer  (26)
  • American Chemical Society
  • Nature Publishing Group
Collection
Keywords
Publisher
  • Springer  (26)
  • American Chemical Society
  • Nature Publishing Group
  • Wiley-Blackwell  (2)
Years
  • 1
    Electronic Resource
    Electronic Resource
    Displacement of lidocaine from serumα 1-acid glycoprotein binding sites by basic drugs (1983)
    Springer
    European journal of clinical pharmacology 25 (1983), S. 413-417 
    Details
    ISSN: 1432-1041
    Keywords: lidocaine ; alpha1-acid glycoprotein ; protein binding ; free fraction ; displacement ; basic drug interaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Since little is known of the number and types of binding sites on α1-acid glycoprotein (AAG) and because drug-drug protein binding interactions often fail to fit a simple model, a study of the effect of 9 known AAG binding drugs on lidocaine free fraction (LFF) was performed. Serum was obtained from 10 healthy males, pooled and various concentrations (from 0.15 to 1 000 µg/ml) of amitriptyline, bupivacaine, chlorpromazine, disopyramide, imipramine, meperidine, nortriptyline, propranolol and quinidine were added. LFF was determined by equilibrium dialysis at an initial lidocaine concentration of 2.0 µg/ml. LFF increased from 0.30±0.019 (mean ± SD) in the absence of displacing agents to maximum values ranging from 0.59 (nortriptyline) to 0.73 (bupivacaine). Plots of LFF vs. the logarithm of displacing drug concentration yielded simple sigmoidal curves in all cases. LFF was increased 50% by an initial bupivacaine concentration of 6.0 µg/ml with all other drugs requiring more than 10 µg/ml to increase LFF to that extent. Lidocaine binding in a 4.5 g/dl albumin solution was unaffected by concentrations of quinidine, meperidine, nortriptyline and bupivacaine up to 200 µg/ml. Addition of AAG to serum reduced LFF as expected. A plot of the reciprocal of bound drug concentration vs. the reciprocal of free drug concentration in the presence and absence of quinidine suggested a competitive binding interaction. These data indicate that the binding interactions between lidocaine and the various displacing compounds are not significantly complicated by cooperative effects and that, with the possible exception of bupivacaine, displacement of lidocaine by any of these drugs is unlikely to be of clinical significance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01037957
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  • 2
    Electronic Resource
    Electronic Resource
    Pharmacokinetics of intravenous and oral tolmesoxide (1981)
    Springer
    European journal of clinical pharmacology 19 (1981), S. 119-125 
    Details
    ISSN: 1432-1041
    Keywords: tolmesoxide ; metabolite ; volunteers ; pharmacokinetics ; intravenous ; oral ; protein binding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary A high pressure liquid chromatographic assay was developed for simultaneous measurement of the plasma levels of tolmesoxide and its principal metabolite, RX71112. The assay was used to study the disposition of intravenous and oral tolmesoxide in ten normotensive subjects. Two exponential terms were required to describe the disposition of the drug following intravenous administration, whilst a single exponential term sufficied to account for the decay in the plasma concentration after oral administration. The bioavailability of oral tolmesoxide from capsules averaged 84.5% and was independent of dose. The mean half-life after i. v. dosing was 2.6 h (±0.3 SEM) compared to values of 1.9 h (±0.1 SEM) and 2.7 h (±0.5 SEM) following 200 and 400 mg oral doses respectively. In all subjects RX71112 appeared in plasma shortly after tolmesoxide following both routes of administration. The terminal half-life of the metabolite was significantly longer than tolmesoxide with a mean value of 4.9 h (±0.9 SEM) following the 200 mg oral dose of tolmesoxide. The binding of tolmesoxide and RX71112 at therapeutic plasma concentration was 36.8% (±0.5 SEM) and 58.5% (±0.3 SEM) and this remained unchanged at higher concentrations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00568398
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  • 3
    Electronic Resource
    Electronic Resource
    Plasma protein binding of etidocaine during pregnancy and labour (1982)
    Springer
    European journal of clinical pharmacology 22 (1982), S. 451-457 
    Details
    ISSN: 1432-1041
    Keywords: etidocaine ; protein binding ; pregnancy ; alpha1-acid glycoprotein ; labour ; free fatty acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Preliminary studies of the ultrafiltration method for measuring the extent of plasma protein binding of etidocaine showed that etidocaine binding was both pH and concentration dependent. Etidocaine (1 µg/ml) was found to bind avidly to a physiological concentration (74 mg/dl) of α1-acid glycoprotein (α1-AGP) (7.23±0.64%, mean ± SD, unbound). In vitro investigation of etidocaine binding in plasma obtained from blood bank donors and from 19 pregnant women prior to induction of labour, during early labour, mid-labour and delivery showed no difference in etidocaine binding (10.3±3.3%, 7.06±2.66%, 8.15±2.57%, 7.84±3.74% and 9.28±6.06% unbound respectively). There was a significant increase in the mean plasma total free fatty acid (FFA) concentration from pre-labour (0.535±0.240 mM) to delivery (0.948±0.28 mM), while plasma albumin and β-lipoprotein concentrations remained constant. α1-Acid glycoprotein concentration tended to increase slightly from pre-labour to early labour (p〈0.1) but was still within the normal physiological range. There was no correlation between etidocaine binding ratio and the concentrations of FFA or plasma proteins except for a poor correlation with the α1-AGP concentration (r=0.361, p〈0.05). Storage of plasma and inadequate control of plasma pH during ultrafiltration appeared to give spurious binding values. These studies with the extensively bound basic drug etidocaine suggest that unlike many acidic drugs which are bound predominantly to serum albumin, the binding of α1-AGP — bound basic drugs may be unaffected by pregnancy and labour.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00542552
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  • 4
    Electronic Resource
    Electronic Resource
    Pharmacokinetics and bioavailability of intravenous, oral, and rectal nitrazepam in humans (1982)
    Springer
    Journal of pharmacokinetics and pharmacodynamics 10 (1982), S. 231-245 
    Details
    ISSN: 1573-8744
    Keywords: nitrazepam ; i.v. ; oral ; rectal administration ; protein binding ; pharmacokinetics ; bioavailability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The pharmacokinetics and bioavailability of nitrazepam following intravenous, oral (tablet), and rectal (solution) administration were studied in seven healthy, young male volunteers. Nitrazepam plasma concentrations were determined by electron-capture GLC; pharmacokinetic evaluations were made by compartmental analysis (NONLIN) and compared with the results obtained by a less stringent modelling of the data. The plasma concentration-time profile was similar for all three routes of administration. Mean kinetic parameters as obtained by compartmental analysis of i.v. nitrazepam were: distribution half-life 17 min; volume of distribution after equilibrium 2.14 liters/kg; total plasma clearance 61.6 ml/min; elimination half-life 29.0 h. The mean protein unbound fraction of nitrazepam in plasma was 12.3% and the clearance of the unbound fraction was 506 ml/min. Absorption of oral nitrazepam started after the elapse of a lag time (mean value 12 min) and occurred as an apparent first-order process in all but one subject, with a mean absorption half-life of 16 min. Distribution and elimination half-lives were comparable with those following i.v. administration. Following rectal administration of the nitrazepam solution, rapid first-order absorption occurred with a mean lag time of 4 min and a mean absorption half-life of 9 min. Peak times (median 18 min) were significantly shorter than following oral administration (median 38 min), but there was little difference in peak concentrations. The distribution half-life was similar to i.v. and oral administration, but the elimination half-lives were longer with a mean value of 33.1 h. Following i.v. administration a good agreement was found between the results obtained by compartmental analysis using NONLIN and those obtained by a less stringent modelling of the data. Following oral and rectal administration, a good agreement between the two procedures was found for the elimination half-life; estimation of bioavailability, however, was higher by compartmental analysis. The mean bioavailability data showed that absorption is complete when nitrazepam is given orally and almost 20% lower when it is given rectally, but considerable interindividual differences were observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01059259
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  • 5
    Electronic Resource
    Electronic Resource
    Disposition of sulfadimethoxine in swine: Inclusion of protein binding factors in a pharmacokinetic model (1982)
    Springer
    Journal of pharmacokinetics and pharmacodynamics 10 (1982), S. 539-550 
    Details
    ISSN: 1573-8744
    Keywords: Sulfadimethoxine ; swine ; pharmacokinetic modelling ; protein binding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Sulfadimethoxine was administered intravenously and orally to five swine. More than 75% of the dose was excreted into urine as the acetyl metabolite with 4–6% excreted unchanged. Plasma and urine data were not consistent when a linear pharmacokinetic model was used to describe the data. Sulfadimethoxine has a high affinity for plasma protein, and the data were subsequently fitted to a nonlinear model, which included saturable protein binding. The choice of a nonlinear model was further supported by a minimum value for the Akaike information criteria. The protein binding constant obtained was 2.8× 104 M−1 and the total protein binding site concentration in plasma was 4.6×10−4 m. Both values are comparable with in vitrodata. This result suggests that the nonlinear model involving protein binding can be successfully applied to pharmacokinetic data. The apparent biological half-life of Sulfadimethoxine (free and bound) in plasma was 14 hr; however, the half-life of elimination of free drug was 1.25 hr. Following oral administration, all of the dose was absorbed with an apparent absorption half-life of 2.9 hr.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01059036
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  • 6
    Electronic Resource
    Electronic Resource
    Lack of interaction between meloxicam and warfarin in healthy volunteers (1997)
    Springer
    European journal of clinical pharmacology 51 (1997), S. 421-425 
    Details
    ISSN: 1432-1041
    Keywords: Key words Warfarin ; Meloxicam ; interaction ; pharmacokinetics ; protein binding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Objective: The effect of multiple oral doses of meloxicam 15 mg on the pharmacodynamics and pharmacokinetics of warfarin was investigated in healthy male volunteers. Warfarin was administered in an individualized dose to achieve a stable reduction in prothrombin times calculated as International Normalized Ratio (INR) values. Then INR- and a drug concentration-time profile was determined. For the interaction phase, meloxicam was added for 7 days and then INR measurements and the warfarin drug profiles were repeated for comparison. Overall, warfarin treatment lasted for 30 days. Results: Warfarin and meloxicam were well tolerated by healthy volunteers in this study. Thirteen healthy volunteers with stable INR values entered the interaction phase. Prothrombin times, expressed as mean INR values, were not significantly altered by concomitant meloxicam treatment, being 1.20 for warfarin alone and 1.27 for warfarin with meloxicam cotreatment. R- and S-warfarin pharmacokinetics were similar for both treatments. Geometric mean (% gCV) AUCSS values for the more potent S-enantiomer were 5.07 mg · h · l−1 (27.5%) for warfarin alone and 5.64 mg · h · l−1 (28.1%) during the interaction phase. Respective AUCSS values for R-warfarin were 7.31 mg · h · l−1 (43.8%) and 7.58 mg · h · l−1 (39.1%). Conclusion: The concomitant administration of the new non-steroidal anti-inflammatory drug (NSAID) meloxicam affected neither the pharmacodynamics nor the pharmacokinetics of a titrated warfarin dose. A combination of both drugs should nevertheless be avoided and, if necessary, INR monitoring is considered mandatory.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002280050224
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  • 7
    Electronic Resource
    Electronic Resource
    Theoretical analysis of the binding of salicylate by human serum albumin: The relationship between free and bound drug and therapeutic levels (1976)
    Springer
    European journal of clinical pharmacology 9 (1976), S. 285-290 
    Details
    ISSN: 1432-1041
    Keywords: Salicylate ; human serum albumin ; protein binding ; theoretical analysis ; hypoalbuminemia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The binding of salicylate by human serum albumin was analyzed by use of a computer program using previously published association constants and binding capacities for the two sets of binding sites on the protein. The analysis consisted of computing free and bound salicylate for a range of therapeutic and toxic concentrations from 181 to 7246 µmole/L (25 to 1000 mg/L). At low and therapeutic levels the total amount of bound drug would exceed the amount of free drug. At higher levels, which included therapeutic and toxic ranges, the amount of free drug would equal or exceed the amount of bound salicylate. At low levels of drug in the plasma, up to 2000 µmole/L the high affinity sites (Site 1), would bind most of the drug, but as the concentration of drug increased this site would approach saturation and the low affinity Site 2 would bind increasing amounts of salicylate. At high salicylate levels the amount of drug bound by the low affinity sites would exceed the amount bound by the high affinity sites. Computation also showed that when the total amount of protein in the analysis was reduced, from 5,4,3 to 2 gm%, as in hypoalbuminemia, the total amount of drug bound by the protein would decrease and the quantity of free drug would increase. The amount of drug bound by each of the two sets of sites also fell as the concentration of protein decreased. Some of the possible clinical implications of these findings are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00561662
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  • 8
    Electronic Resource
    Electronic Resource
    Interindividual differences in chlorthalidone concentration in plasma and red cells of man after single and multiple doses (1976)
    Springer
    European journal of clinical pharmacology 9 (1976), S. 319-325 
    Details
    ISSN: 1432-1041
    Keywords: Chlorthalidone ; diuretics ; drug plasma concentration ; protein binding ; red blood-cell concentration ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary A gas chromatographic method has been employed to determine chlorthalidone in plasma and whole blood after therapeutic doses. Radioactively labelled chlorthalidone was used for in vitro studies of the uptake of chlorthalidone from plasma by red blood cells. Chlorthalidone was markedly concentrated in red cells and as a compartment they would account for at least 30% of total drug in the body after multiple doses. The ratio between the plasma and red cell concentration of chlorthalidone varied between individuals. After a single oral dose of 50 mg in 6 healthy volunteers chlorthalidone was eliminated with a half-life of 51 to 89 hours. The apparent volume of distribution varied between 3 and 13 1/kg and the clearance between 53 and 145 ml/min. The mean steady-state plasma concentrations during treatment with a standard dose of 50 mg daily (n=10) varied 5-fold between individuals. During the steady state approximately 50% of the daily dose was excreted unchanged in the urine during 24 hrs. The plasma levels observed in patients were higher than those predicted from the single oral dose studies in healthy volunteers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00561667
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  • 9
    Electronic Resource
    Electronic Resource
    The protein binding of vinblastine in the serum of normal subjects and patients with Hodgkin's disease (1983)
    Springer
    European journal of clinical pharmacology 24 (1983), S. 683-687 
    Details
    ISSN: 1432-1041
    Keywords: vinblastine ; protein binding ; Hodgkin's disease
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The protein binding of vinblastine was measured in the serum from 6 normal subjects and 9 patients with Hodgkin's disease. Cellulose acetate electrophoresis showed that the predominant binding protein fractions were the α1- and α2-globulins with little binding to albumin and β- and γ-globulins. At a serum concentration of 10 nM a significantly lower percentage bound was found in the patient group (p=0.001). Binding to both groups was very high at 99.7% bound in the normal subjects and 98.9% bound in the patient group. Binding in both groups was best described by a two class protein binding model with higher and lower affinity binding sites. No significant difference was found on inter-group comparisons of binding parameter values.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00542223
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  • 10
    Electronic Resource
    Electronic Resource
    Intravenous quinidine in congestive cardiomyopathy (1981)
    Springer
    European journal of clinical pharmacology 19 (1981), S. 173-176 
    Details
    ISSN: 1432-1041
    Keywords: cardiomyopathy ; quinidine ; left ventricular performance ; protein binding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Eight male patients with compensated congestive cardiomyopathy received single 300-mg doses of intravenous quinidine by 15-min infusion. Left ventricular (LV) performance was evaluated by echocardiography at multiple points in time during the next 24 h. Quinidine kinetics and protein binding were determined from multiple serum samples drawn for up to 36 h after dosage. LV function was not impaired. Instead, quinidine transiently increased ejection fraction (mean: +39%) and rate of circumferential shortening (mean: +46%). Endsystolic and end-diastolic LV internal diameter likewise were decreased (means: −13% and −7%). Blood pressure and ventricular rate were not significantly altered. Compared to 8 healthy controls matched for age, sex, and weight, quinidine volume of distribution among patients was smaller (means: 2.27 vs 1.90 l/kg), as was total quinidine clearance (3.49 vs 2.84 ml/min/kg); however, differences were not statistically significant. Well-controlled, slow intravenous infusion of quinidine does not impair LV performance and is safe for patients with compensated congestive cardiomyopathy. However, such patients may have reduced quinidine clearance and hence require lower doses than expected based on age and weight.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00561944
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