摘要:

Clinical Pharmacology and Therapeutics(1991)50, 641–646; doi:10.1038/clpt.1991.2

ISSN:0009-9236    

DOI:10.1038/clpt.1991.201

年代:1991

数据来源: WILEY

摘要:

Clinical Pharmacology and Therapeutics(1991)50, 647–649; doi:10.1038/clpt.1991.2

ISSN:0009-9236    

DOI:10.1038/clpt.1991.202

年代:1991

数据来源: WILEY

摘要:

Among 70 patients with arthritis who were receiving satisfactory maintenance therapy with sulindac (300 to 400 mg daily), 64% had no detectable sulindac sulfide (active metabolite) in one to four random urine specimens. However, 36% had 1.0 to 7.8 (mean, 2.2 ± 1.4) µg/ml sulindac sulfide in urine, similar to the therapeutically effective concentrations found in 24 concurrent plasma specimens (1.4 to 9.0 µg/ml). Ten patients had sulindac sulfide in only one or two of two to four urine specimens. Thus, 36% of the patients had pharmacodynamically significant concentrations of sulindac sulfide in urine, presumably capable of suppressing the cyclooxygenase pathway responsible for prostaglandin synthesis in the kidney and elsewhere. The findings suggest individual variability in the capacity for renal oxidation of sulindac sulfide to inactive metabolites, perhaps related to genetic or environmental factors or both. These findings may help to explain conflicting reports on the effects of sulindac on urinary prostaglandins and renal function.Clinical Pharmacology and Therapeutics(1991)50, 650–655; doi:10.1038/clpt.199

ISSN:0009-9236    

DOI:10.1038/clpt.1991.203

年代:1991

数据来源: WILEY

摘要:

The concentration‐effect relationship of alprazolam plasma concentration and growth hormone changes was studied in six healthy volunteers by use of three different intravenous bolus doses of alprazolam (0.003, 0.007, and 0.02 mg/kg) in a random blind order. There was a linear increase in peak concentration (Cmax) and area under the curve (AUC) of alprazolam with increasing dose (r= 0.96). There was no significant correlation between alprazolam Cmaxand effect on growth hormone measured as either maximum increase or maximum percentage change from baseline. There was, however, an overall positive correlation (r= 0.58) between the AUC values of alprazolam and growth hormone from 0 to 120 minutes, although the relative degree of increased AUC of growth hormone with increasing AUC of alprazolam varied greatly across individuals. The difficulties of interpreting the mechanisms underlying differential growth hormone responses even when concentration of stimulus is controlled are discussed.Clinical Pharmacology and Therapeutics(1991)50, 656–662; doi:10.1038/clpt.1991

ISSN:0009-9236    

DOI:10.1038/clpt.1991.204

年代:1991

数据来源: WILEY

摘要:

Xanthine oxidase catalyzes the biotransformation of many drugs, including the thiopurines and methylxanthines. We used a sensitive radiochemical assay to determine optimal conditions for the assay of human liver xanthine oxidase activity. We then used those assay conditions to study the nature and extent of individual variation of xanthine oxidase activity in 189 samples of hepatic tissue from patients undergoing clinically indicated partial hepatectomy or open liver biopsy. The average hepatic xanthine oxidase activity was 21% higher in samples from male patients than in those from female patients (1.27 ± 0.43 [mean ± SD,n= 92] versus 1.05 ± 0.38 U/gm tissue [n= 97,p<0.0001], respectively). Seventynine of these tissue samples had been obtained from patients with normal liver function studies and normal serum creatinine values. Average xanthine oxidase activity in these 79 samples remained approximately 20% higher for men than for women (1.35 ± 0.38 versus 1.12 ± 0.33 U/gm tissue, respectively). Probit analysis of the data for samples from patients with normal liver function studies and normal creatinine values suggested the presence of a subgroup of samples with relatively low xanthine oxidase activity in 21% (9 of 42) of male patients and 27% (10 of 37) of female patients. These observations may have implications with regard to individual variation in the biotransformation of drugs metabolized by xanthine oxidase.Clinical Pharmacology and Therapeutics(1991)50, 663–672; doi:10.1038/clpt.1

ISSN:0009-9236    

DOI:10.1038/clpt.1991.205

年代:1991

数据来源: WILEY

摘要:

Twenty‐two patients who were receiving hemodialysis were studied in three groups of eight subjects each to assess the pharmacokinetics during the dialysis‐free interval and during hemodialysis treatment and to assess the pharmacodynamics of cisapride. Cisapride and its metabolite norcisapride were measured by use of HPLC and gas chromatography, respectively. The pharmacodynamic effect of cisapride was measured by means of radionuclide gastric emptying. After a single oral dose of 20 mg the terminal half‐life of cisapride was 9.6 ± 3.3 hours, the volume of distribution was 4.8 ± 3.3 L/kg, the total oral plasma clearance was 380 ± 161 ml/min, the area under the curve was 1024 ± 447 ng · hr/ml (mean ± SD). Norcisapride only could be detected in the dialysate (0.36 ± 0.067 mg) and was eliminated by a hemodialysis clearance of 34.7 ± 7.9 ml/min. Cisapride reduced gastric retention from 77.6% ± 21.1% to 43.7% ± 18.2% of maximum filling (40 minutes after meals) and normalized the abnormal gastric emptying time in patients receiving dialysis. Cisapride dosage adjustment or substitution after hemodialysis is not necessary.Clinical Pharmacology and Therapeutics(1991)50, 673–681; doi:10.

ISSN:0009-9236    

DOI:10.1038/clpt.1991.206

年代:1991

数据来源: WILEY

摘要:

Pefloxacin and rifampin are frequently associated in the antibiotic therapy of deep‐seated, and especially bone‐located, infections. The influence of rifampin, a potent drug metabolism enzyme inducer, on the pharmacokinetics of pefloxacin was studied in a randomized crossover trial involving eight young healthy male volunteers. Every volunteer received either pefloxacin alone (period A) or pefloxacin after a 10‐day induction by rifampin (period B) given as a 900 mg daily oral dose, and both periods were separated by a 3‐week washout period. During both periods, pefloxacin was given during 3 days as a 400 mg b.i.d. oral dose (six doses) followed by a 400 mg intravenous dose on the fourth day. The kinetics of pefloxacin are significantly influenced by rifampin: The minimum (12‐hour) plasma concentration, area under the concentration‐time curve, and elimination half‐life decreased respectively from 4.26 ± 1.57 to 2.70 ± 1.00 mg/L, 78.91 ± 22.82 to 57.81 ± 16.69 mg · hr/L, 14.46 ± 3.46 to 10.08 ± 2.44 hours(p<0.05). The renal clearance of pefloxacin was unchanged, but the plasma clearance increased from 94.04 ± 39.04 to 126.82 ± 47.36 ml/min(p<0.05). The plasma clearance ofN‐demethyl andN‐oxide metabolites were similar for both periods, but the cumulative renal excretion (0 to 96 hours) decreased significantly(p<0.01) for period B versus period A. This definite but moderate inductive effect of rifampin on the pharmacokinetics of pefloxacin does not suggest a dose modification of pefloxacin in therapeutic association with rifampin, but pefloxacin assay in plasma seems to be advisable.Clinical Pharmacology and Therapeutics(1991)50, 682–6

ISSN:0009-9236    

DOI:10.1038/clpt.1991.207

年代:1991

数据来源: WILEY

摘要:

IntroductionThe normal nonrenal clearance of vancomycin is reduced in patients with chronic renal failure (40 versus 6 ml/min). The nonrenal clearance of vancomycin in patients with acute renal failure has not been characterized extensively.PurposeTo prospectively determine the pharmacokinetic profile of vancomycin in anuric patients with acute renal failure who are receiving continuous venovenous hemofiltration.MethodsVancomycin serum samples were obtained in 10 patients immediately before and 1 and 12 hours after a 1‐hour infusion. Thirteen sets of data were obtained. Vancomycin concentration data were incorporated into a first‐order, single‐compartment model. Determinations for the area under the serum concentration–time curve were made by the trapezoidal rule.ResultsTotal vancomycin clearance was 28.5 ± 6.4 ml/min (range, 17.1 to 36.6 ml/min. Hemofilter clearance was either 6.7 or 13.3 ml/min, depending on ultrafiltrate production rate (assuming a sieving coefficient of 0.8). Nonrenal clearance, calculated as total clearance minus hemofilter clearance was 16.2 ± 7.0 ml/min (range, 3.8 to 23.3 ml/min). Total clearance did not correlate with hemofilter clearance (r= 0.1;p>0.25) but correlated strongly with nonrenal clearance (r = 0.94;p<0.0005). Nonrenal clearance decreased significantly as the days on continuous venovenous hemofiltration increased (range, 2 to 14 days;r= 0.68;p<0.025).ConclusionEarly in the course of acute renal failure there is a substantial preservation of the normal nonrenal clearance of vancomycin. This nonrenal clearance appears to decrease with the duration of renal failure, eventually approaching the clearance observed in patients with chronic failure.Clinical Pharmacology and Therapeutics(1991)50, 688–694; doi:10.1038/c

ISSN:0009-9236    

DOI:10.1038/clpt.1991.208

年代:1991

数据来源: WILEY

摘要:

The disposition of acetaminophen after oral administration was investigated in adults with cystic fibrosis(n= 5) and in age‐matched healthy control subjects(n= 5). The total plasma clearance of acetaminophen was found to be greater(p<0.025) in subjects with cystic fibrosis (0.362 ± 0.081 L/hr/kg) than in control subjects (0.247 ± 0.022 L/hr/kg). This difference in clearance was found to be primarily attributable to a greater metabolic clearance of acetaminophen to acetaminophen sulfate (0.080 ± 0.023 L/hr/kg for subjects with cystic fibrosis and 0.045 ± 0.008 L/hr/kg for control subjects;p<0.05) and to a greater metabolic clearance of acetaminophen to acetaminophen glucuronide (0.189 ± 0.051 L/hr/kg for subjects with cystic fibrosis and 0.114 ± 0.017 L/hr/kg for control subjects;p<0.05) in persons with cystic fibrosis. Of the mechanisms that may be responsible for these differences, the most likely is enhanced activity (in subjects with cystic fibrosis) of the transferases that mediate the metabolism of acetaminophen to acetaminophen sulfate and acetaminophen glucuronide, respectively.Clinical Pharmacology and Therapeutics(1991)50, 695–701; doi:10.1038/clp

ISSN:0009-9236    

DOI:10.1038/clpt.1991.209

年代:1991

数据来源: WILEY

摘要:

Different recombinant human erythropoietin products have been developed. Although they appear to have similar pharmacokinetics and function, these have not been directly compared. This randomized, double‐blind, four‐period crossover study compared the pharmacokinetics and pharmacodynamics of intravenous and subcutaneous epoetin alfa and epoetin beta in 18 normal male volunteers. As a control, three subjects received placebo treatment. After intravenous administration, the steady‐state volume of distribution and β‐phase volume of distribution of epoetin beta were 7.7% and 16.9% larger than for epoetin alfa (p<0.05). The terminal elimination half‐life after intravenous administration of epoetin beta was 20% longer than the terminal elimination half‐life of epoetin alfa. After subcutaneous administration there was a delayed drug absorption with epoetin beta compared with epoetin alfa (p<0.05). There was a small but significantly greater absolute reticulocyte response after subcutaneous epoetin beta compared with subcutaneous epoetin alfa. The findings support differences in the pharmacokinetics and function of epoetin alfa and beta that are possibly caused by differences in their glycosylation.Clinical Pharmacology and Therapeutics(1991)50, 702–712; doi:10.103

ISSN:0009-9236    

DOI:10.1038/clpt.1991.210

年代:1991

数据来源: WILEY