Effects of amoxicillin/clavulanic acid on the pharmacokinetics of valproic acid.

Valproic acid (VPA) is mainly metabolized via glucuronide, which is hydrolyzed by ß-glucuronidase and undergoes enterohepatic circulation. Amoxicillin/clavulanic acid (AMC) administration leads to decreased levels of ß-glucuronidase-producing bacteria, suggesting that these antibiotics could interrupt enterohepatic circulation and thereby alter the pharmacokinetics of VPA. This study aimed to evaluate the effects of AMC on the pharmacokinetics of VPA. This was an open-label, two-treatment, one-sequence study in 16 healthy volunteers. Two treatments were evaluated; treatment VPA, in which a single dose of VPA 500 mg was administered, and treatment AMC + VPA, in which multiple doses of AMC 500/125 mg were administered three times daily for 7 days and then a single dose of VPA was administered. Blood samples were collected up to 48 hours. Pharmacokinetic parameters were calculated using noncompartmental methods. Fifteen subjects completed the study. Systemic exposures and peak concentrations of VPA were slightly lower with treatment AMC + VPA than with treatment VPA (AUClast, 851.0 h·mg/L vs 889.6 h·mg/L; C max, 52.1 mg/L vs 53.0 mg/L). There were no significant between-treatment effects on pharmacokinetics (95% confidence interval [CI]) of AUClast and C max (95.7 [85.9-106.5] and 98.3 [91.6-105.6], respectively). Multiple doses of AMC had no significant effects on the pharmacokinetics of VPA; thus, no dose adjustment is necessary.

Multiple-Dose Study to Evaluate Pharmacokinetics, Pharmacodynamics, and Safety in Healthy Subjects: A Comparison of Controlled-Release Sarpogrelate and Immediate-Release Sarpogrelate.

AIMS: To compare the pharmacokinetics, pharmacodynamics, and safety of sarpogrelate between controlled-release (CR) and immediate-release (IR) formulations after multiple-dose administration. METHODS: This study was a randomized, open-label, 2-period, 2-treatment, crossover study in healthy subjects. All subjects received CR sarpogrelate 300 mg once daily and IR sarpogrelate 100 mg three times daily by random order each for 3 days with a 7-day washout period. Serial blood sampling was performed over 24 h. Pharmacokinetic parameters were determined by noncompartmental methods. Platelet aggregation to collagen, measured by light transmission aggregometry, was reported as maximal platelet aggregation. RESULTS: Thirty-two subjects completed the study. CR sarpogrelate increased rapidly, reaching Cmax in 1.25 h (vs. 1.00 h in IR sarpogrelate) and declined with a t1/2 of 3.59 h (vs. 1.12 h in IR sarpogrelate). The 90% CIs for the geometric mean ratio of AUCτ and Cmax,ss between IR and CR formulations were 1.18 to 1.40 and 0.99 to 1.29, respectively. The degree of inhibition of platelet aggregation was similar between two formulations. CONCLUSIONS: CR sarpogrelate showed slightly higher systemic exposure and similar peak concentration compared with IR sarpogrelate. The profiles of pharmacodynamics and safety were comparable between two formulations.

Bioequivalence evaluation of two amlodipine salts, besylate and orotate, each in a fixed-dose combination with olmesartan in healthy subjects.

A fixed-dose combination of amlodipine and olmesartan is used to treat high blood pressure in patients whose hypertension is not sufficiently controlled with either drug alone. The objective of this study was to evaluate the bioequivalence of two fixed-dose combinations, ie, amlodipine orotate/olmesartan medoxomil 10/40 mg and amlodipine besylate/olmesartan medoxomil 10/40 mg, in healthy subjects. A randomized, open-label, single-dose, two-sequence, two-period, crossover study was conducted in 30 healthy adult volunteers. Blood samples were collected for up to 72 hours post-dose in each period. Safety data included the results of physical examinations, clinical laboratory tests, vital signs, an electrocardiogram, and adverse events. For both amlodipine and olmesartan, the 90% confidence intervals for the geometric mean ratios of AUClast and time to peak plasma concentration fell within the bioequivalence acceptance criteria. The two fixed-dose combinations showed similar safety profiles. Amlodipine orotate/olmesartan medoxomil 10/40 mg was bioequivalent to amlodipine besylate/olmesartan medoxomil 10/40 mg.

Lack of the effect of lobeglitazone, a peroxisome proliferator-activated receptor-γ agonist, on the pharmacokinetics and pharmacodynamics of warfarin.

AIMS: Lobeglitazone has been developed for the treatment of type 2 diabetes mellitus. This study was conducted to evaluate potential drug-drug interactions between lobeglitazone and warfarin, an anticoagulant with a narrow therapeutic index. METHODS: In this open-label, three-treatment, crossover study, 24 healthy male subjects were administered lobeglitazone (0.5 mg) for 1-12 days with warfarin (25 mg) on day 5 in one period. After a washout interval, subjects were administered warfarin (25 mg) alone in the other period. Pharmacokinetics of R- and S-warfarin and lobeglitazone, as well as pharmacodynamics of warfarin, as measured by international normalized ratio (INR) and factor VII activity, were assessed. RESULTS: The geometric mean ratios (GMRs) and 90% confidence intervals (CIs) for area under the curve from time zero to the time of the last quantifiable concentration (AUClast) for warfarin + lobeglitazone: warfarin alone were 1.0076 (90% CI: 0.9771, 1.0391) for R-warfarin and 0.9880 (90% CI: 0.9537, 1.0235) for S-warfarin. The maximum observed plasma concentration (C max) values were 1.0167 (90% CI: 0.9507, 1.0872) for R-warfarin and 1.0028 (90% CI: 0.9518, 1.0992) for S-warfarin, both of which were contained in the interval 0.80-1.25. Lobeglitazone had no effect on the area under the effect-time curve from time 0 to 168 hours (AUEC) of INR and factor VII activity, as demonstrated by the GMRs of 1.0091 (90% CI: 0.9872, 1.0314) and 0.9355 (90% CI: 0.9028, 0.9695), respectively. In addition, the pharmacokinetics of lobeglitazone was also unaffected by warfarin. CONCLUSION: Concomitant administration of lobeglitazone and warfarin was well tolerated. Lobeglitazone had no meaningful effect on the pharmacokinetics or pharmacodynamics of warfarin. These findings indicate that lobeglitazone and warfarin can be coadministered without dosage adjustments for either drug.

A pharmacokinetic and pharmacodynamic drug interaction between rosuvastatin and valsartan in healthy subjects.

PURPOSE: Valsartan, an angiotensin-receptor blocker, and rosuvastatin, a competitive inhibitor of the 3-hydroxy-3-methylglutaryl coenzyme A reductase, are frequently coadministered to treat patients with hypertension and dyslipidemia. The study reported here sought to evaluate the pharmacokinetic and pharmacodynamic interactions between rosuvastatin and valsartan in healthy Korean subjects. SUBJECTS AND METHODS: Thirty healthy male Korean subjects were administered with rosuvastatin (20 mg/day), valsartan (160 mg/day), and both drugs concomitantly for 4 days in a randomized, open-label, multiple-dose, three-treatment, three-period crossover study. Plasma concentrations of rosuvastatin, N-desmethyl rosuvastatin, and valsartan were determined using validated high-performance liquid chromatography with tandem mass spectrometry. Lipid profiles and vital signs (systolic and diastolic blood pressure and pulse rate) were measured for the pharmacodynamic assessment. RESULTS: For rosuvastatin, the geometric mean ratios (90% confidence intervals [CIs]) of coadministration to mono-administration were 0.8809 (0.7873-0.9857) for maximum plasma concentration at steady state and 0.9151 (0.8632-0.9701) for area under the concentration-time curve (AUC) over a dosing interval at steady state. For valsartan, the geometric mean ratios (90% CIs) of those were 0.9300 (0.7946-1.0884) and 1.0072 (0.8893-1.1406), respectively. There were no significant differences in the metabolic ratio of N-desmethyl rosuvastatin AUC to rosuvastatin AUC between coadministration and rosuvastatin alone. No interaction was found in terms of systolic or diastolic blood pressure or lipid profiles. Combined treatment with valsartan and rosuvastatin was generally well tolerated without serious adverse events. CONCLUSION: The pharmacokinetic profiles of rosuvastatin and valsartan in combination were comparable with those of rosuvastatin and valsartan administered individually, suggesting that their individual pharmacokinetics were not affected by their coadministration. No dose adjustment was required and the results are supportive of a study in a larger patient population.