The pharmacokinetics of pioglitazone in Thai healthy subjects.

BACKGROUND: Pioglitazone is a thiazolidinedione compound used in the treatment of type 2 diabetes, metabolized mainly by CYP2C8 and CYP3A4. Due to genetic polymorphisms in CYP2C8, interethnic variability in pharmacokinetics should be considered. OBJECTIVE: To conduct a study on the pharmacokinetics of pioglitazone in Thai subjects. MATERIAL AND METHOD: The present study was performed in 24 Thai male healthy subjects. After an overnight fasting, each subject had a single oral dose of 30 mg pioglitazone tablet. Serial blood samples were collected before and at 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 5, 6, 9, 12, 24 and 48 hours after drug administration. Plasma pioglitazone was determined by automated High Performance Liquid Chromatography (HPLC) with UV detection after deproteinized with acetonitrile. The relevant pharmacokinetic parameters including peak plasma concentration (Cmax), time to peak plasma concentration (Tmax), elimination rate constant (Kel), elimination half-life (T1/2), area under the plasma concentration-time curve (AUC(0-t), AUC(0-inf)), clearance (Cl) and volume of distribution (Vd) were determined. RESULTS: After a single oral dose of 30 mg pioglitazone tablet, the drug was absorbed into systemic circulation with time to maximum concentration (Tmax) at 2.00 +/- 1.61 (0.5-6) hr, and the plasma level reached the maximum concentration (Cmax) of 1.14 +/- 0.29 (0.47-1.63) microg/ml. The AUC was 11.47 +/- 4.77 and 16.69 +/- 7.75 microg x hr/ml for AUC(0-t) and AUC(0-inf) respectively. The elimination rate constant (Kel) of pioglitazone obtained was 0.08 +/- 0.04 hr(-1), whereas the t1/2 was 11.19 +/- 7.38 hrs with the clearance (Cl) of 2.26 +/- 1.22 L/hr. The apparent volume of distribution (Vd) was found to be 30.19 +/- 13.06 L. CONCLUSION: Pharmacokinetic parameters of 30 mg single oral dose of pioglitazone were characterized in Thai subjects. These parameters showed that pioglitazone had a rapid rate of absorption, small volume of distribution and short elimination half-life.

Evaluation of the bioequivalence of zidovudine 100 mg capsules in healthy Thai male volunteers.

OBJECTIVE: The bioequivalence study of two oral formulations of zidovudine were evaluated; Antivir (Government Pharmaceutical Organization (GPO), Thailand) as the test formulation and Retrovir (Glaxo-SmithKline, USA), as the reference formulation. MATERIAL AND METHOD: The two products were orally administered as a single dose of 100 mg zidovudine three capsules according to a randomized two-way crossover design to 28 healthy fasted Thai male volunteers. The washout period between treatments was 1 week. After drug administration, serial blood samples were collected at a specific time interval from 0-10 hours. The plasma zidovudine concentrations were determined via HPLC technique. Individual plasma zidovudine concentration-time profile was analyzed for relevant pharmacokinetic parameters; the comparative bioavailability of the two products was determined by the analysis of variance (ANOVA) for two way crossover design, using logarithmic transformed data. RESULTS: The results found that the mean peak (X+/- SD) plasma concentration (Cmax) of Antivir was 3.34 +/- 0.15 ng/mL and of Retrovir was 3.32 +/- 0.21 ng/mL. The 90% confidence interval (CI) for the difference of mean Cmax was 90.76-120.81%. The time to peak plasma concentration (Tmax) of Antivir was 0.49 +/- 0.16 hours and for Retrovir was 0.62 +/- 0.35 hours with a difference time to peak of 20.96%. The half life (t1/2) of Antivir was 1.16 +/- 0.28 hours and t1/2 of Retrovir was 1.05 +/- 0.25 hours. The mean area under the curve (AUC0-->t) of Antivir was 3.34 +/- 0.12 ng.hr/mL and of Retrovir was 3.35 +/- 0.15 ng.hr/mL. The 90%CI for the difference ofmean AUC0-->t was 91.83-103.99%. The mean AUC0-->infinity of Antivir was 3.37 +/- 0.12 nghr/mL and for and Retrovir was 3.38 +/- 0.14 ng.hr/mL. The 90%CI for the difference of mean AUC0-->infinity was 91.22-104.69%. CONCLUSION: The present study revealed that the 90%CI for the difference of Cmax AUC0-->t and AUC0-->infinity means were in the criteria ofacceptance, which should be within 80-125%. Thus, the present study demonstrated the bioequivalence of the test drug (Antivir) and the reference drug (Retrovir).

Clinical pharmacokinetic of celecoxib in healthy Thai volunteers.

BACKGROUND: Celecoxib, a nonsteroidal antiinflammatory drug exhibits its antiinflammatory effect by selective inhibition of cyclooxygenase-2 (COX-2) enzyme. Its efficacy has been accepted for the treatment of arthritic pain with superior gastrointestinal side effect profile compared with other conventional NSAIDs. OBJECTIVE: To elucidate clinical pharmacokinetic of celecoxib following an oral dose administration. MATERIAL AND METHOD: Eighteen healthy Thai male volunteers were enrolled in the present study. Their mean age was 20.94 +/- 1.21 years and their mean weight was 63 +/- 5.17 kg. They were orally administered 200 mg celecoxib after an over night fasting, serial blood samples were drawn before and at 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 5, 6, 8, 10, 12, 24 and 48 hours after dosing. Plasma celecoxib was analysed by reversed-phase HPLC. RESULTS: Following a 200 mg celecoxib oral administration, the drug was absorbed into the systemic circulation and reach maximum concentration (Tmax) within 2.50 +/- 1.22 hrs by average with the mean peak concentration (Cmax) of 686.83 +/- 211.35 ng/ml. The extent of absorption (area under the curve, AUC) was approximately 5157.12 +/- 1499.46 and 5911.48 +/- 1363.51 ng hr/ml for AUC(0-->t) and AUC(0-->infinity) respectively. The apparent volume of distribution (Vd) was found to be 458.93 +/- 323.28 L/hr. Celecoxib was eliminated after biotransformation and the metabolites were excreted in both urine and feces. The elimination half-life (t(1/2)) of celecoxib appeared to be 8.79 +/- 5.49 hrs with the apparent clearance (CL) of 35.91 +/- 9.85 L. The elimination rate constant for celecoxib obtained from this present study was about 0.11 +/- 0.05 hr(-1). CONCLUSION: Pharmacokinetic parameters following an oral dose of 200 mg celecoxib administration were characterized, including Cmax, Tmax, Vd, kel, CL, AUC. These parameters reflected absorption, distribution, biotransformation and excretion of celecoxib in healthy Thai volunteers.

Bioequivalence study of postcoital emergency contraceptions containing levonorgestrel.

OBJECTIVE: The progestogen-only method of emergency contraception, levonorgestrel, is one of the effectiveness in preventing expected pregnancies. The comparative bioavailability was carried out on levonorgestrel tablets (0.75 mg) from two different sources (Hungarian and Thai made). METHOD: Eighteen healthy female volunteers were given a single oral dose of 0.75 mg tablets in a crossover design. Serum levonorgestrel concentration was determined by radio-immunoassay. The pharmacokinetic analysis of serum levonorgestrel concentration from each treatment was established. The comparative bioavailability of the two products was determined by the analysis of variance (ANOVA) for two way crossover design. RESULTS: The results found that the mean peak (X +/- SD) serum concentration (Cmax) of the Thai-made pill and Hungarian-pill were 1.18 +/- 0.12 and 1.14 +/- 0.10 ng/ml, respectively. The 90% confidence intervalfor the difference of log Cmax mean was 99.54-120.78%. The time to peak serum concentration (Tmax) of the Thai-made pill and Hungarian-pill were 1.56 +/- 0.73 and 1.58 +/- 0.67 hrs, respectively. The different time of peak serum levonorgestrel concentration was 1.27%. The mean area under the curve (AUC) of Thai-made pill and Hungarian-pill were 2.14 +/- 0.21 and 2.09 +/- 0.16 ng.h/ml, respectively. The 90% confidence interval for the difference of log AUC mean was 103.27 - 121.89%. CONCLUSION: The present study revealed that the 90% confidence interval for the difference of log Cmax mean and log AUC mean were in the criteria of acceptance, which should be within 80-125%. So, the authors can conclude that the Thai-made pill was bioequivalent to the Hungarian-pill.