Comparative study of oral bioavailability of original amoxicillin and local-made amoxicillin used in Siriraj Hospital.

ABSTRACT

Oral bioavailability of single dose of 500 mg Rancil capsule manufactured by Ranbaxy Co., Ltd., which was the generic amoxicillin used in Siriraj Hospital, was compared to that of 500 mg capsule of the reference (original) amoxicillin, i.e., Amoxil-Bencard manufactured by Smith-Kleine & Beecham Inc., using randomized cross-over design. The study was done in 12 healthy volunteers,7 males and 5 females, aged 23-51 years weighing 46-65 kg. Venous blood sampling was taken from each subject prior to and at 0.5, 1, 2, 4, 6 and 8 hr after drug administration. Serum concentrations of amoxicillin were assayed by high performance liquid chromatography (HPLC). Maximum serum concentrations (Cmax) and areas under serum concentration-time curves(AUCs) of both Rancil and Amoxil-Bencard were analysed and compared. The Cmax and AUCs values of Rancil and Amoxil-Bencard were statistically equivalent, i.e., 8.67 ฑ 1.50 ตg/ml v.s. 9.36 ฑ 1.62 mg/ml respectively (p = 0.069) for Cmax ; and 26.02 ฑ 6.80 ตg.hr/ml v.s. 27.51 ฑ 8.52 ตg.hr/ml respectively (p=0.355) for AUC0-8 hr. The 90 % confidence intervals of the Cmax ratio and AUC0-8 hr ratio between Rancilฎ and Amoxil-Bencardฎ were 0.90-1.02 and 0.87-1.11 respectively which were within the acceptable equivalent range of 0.8 - 1.25. Thus, Rancilฎ is considered bioequivalent to and can be used interchangeably with Amoxil-Bencardฎ in clinical infections requiring amoxicillin in order to minimize the cost of treatment.