Pharmacokinetics and bioequivalence testing of generic ondansetron preparations in healthy Thai male volunteers.
METHODS
Pharmacokinetics and bioequivalence of oral preparations of generic ondansetron were investigated in healthy Thai males. The test preparations were Vomitron 8 and Vomitron 4, the reference was Zofran. The three products were administered as an 8 mg single oral dose, in a three-period four-sequence cross-over design with one-week washout period. An intravenous 8 mg Zofran was administered on the forth visit. Plasma ondansetron concentrations were determined by HPLC and the pharmacokinetic parameters were analyzed by non-compartmental analysis.


RESULTS
Following i.v. ondansetron, the mean values of its elimination half-life, its plasma clearance, and its volume of distribution were 4.5 hours, 398 ml/min, and 130 liters, respectively. Its oral bioavailability averaged 67%, and the elimination half-life after oral administration was 5.6 hours. The time to reach the maximal concentration (Tmax, hour) of Zofran (1.21 +/- 0.26) was statistically faster than that of Vomitron 8 (1.33 +/- 0.54) and Vomitron 4 (1.46 +/- 0.50). The 90% confidence intervals of the AUC0-infinity and Cmax ratios muT/muR for (Vomitron 8/Zofran) were 0.88 - 1.12 and 0. 85 - 1.08, respectively. Similarly the 90% CI of the-AUC0-infinity and Cmax ratios for (Vomitron 4/Zofran) were 0.96 - 1.17 and 1.01 - 1.19, respectively.


CONCLUSIONS
These values were within the acceptable range of 0.80 - 1.25, thus our study demonstrated the bioequivalence of Vomitron and Zofran with respect to the rate (Cmax) and extent of absorption (AUC0-infinity).
Rojanasthien
N
N
Department of Pharmacology, Faculty of Medicine, Chiang Mai University, Thailand.
Manorot
M
M
Kumsorn
B
B
D000293:Adolescent; D000328:Adult; D000932:Antiemetics / Q000097:blood / Q000493:pharmacokinetics*; D019540:Area Under Curve; D001682:Biological Availability; D002851:Chromatography, High Pressure Liquid; D018592:Cross-Over Studies; D016568:Drugs, Generic / Q000493:pharmacokinetics*; D006207:Half-Life; D006801:Humans; D008297:Male; D017294:Ondansetron / Q000097:blood / Q000493:pharmacokinetics*; D013785:Thailand; D013810:Therapeutic Equivalency
D000932:Antiemetics; D016568:Drugs, Generic; D017294:Ondansetron