bioequivalence study of two rifampicin capsules formulations: using modified HPLC method

The present work describes the application of the modified HPLC method for bioequivalence study of Rifampicin generic 300 mg capsules [generic] relative to Rifampicin innovator 300 mg capsules [reference]. A sensitive high pressure liquid chromatographic method for the quantitation of rifampicin in human plasma has been established by using water [pH 2.27]: methanol: acetonitrile [1.5:6:12] as a mobile phase. The method allows the analysis of rifampicin in plasma at concentrations ranging from 0.25 to 20 microg/ml. Linearity and precision of the method were validated by analysis of spiked human samples. Accuracy and precision of the method for rifampicin were found to be acceptable. Peak-area ratios [PAR] were used in the determination of plasma concentrations of the drug using indomethacin as an internal standard. The method is sensitive, therefore useful for routine analysis of large number of biological samples. The bioequivalence was carried out on twenty four healthy male volunteers who received a single dose of the test product, Rifampicin generic 300 mg capsules or, the reference product, Rifampicin innovator, 300 mg capsules, in a randomized balanced two ways cross over design. After dosing, serial blood samples were collected for a period of 24 hours. Pharmacokinetic analysis was performed using noncompartmental method. 90% confidence interval for AUC[0-inf], C[max] of test/reference ratio were found to be within the bioequivalence acceptance range of 80% - 125%. It was concluded that Rifampicin generic 300 mg capsules is bioequivalent to Rifampicin innovator 300 mg capsules

study on the possible influence of meloxicam on the pharmacokinetic of a certain narrow therapeutic index drug in rabbits

The present work aimed at evaluating the possible effect of meloxicam on bioavailability and pharmacokinetic of single and repetitive dose of theophylline. The study was conducted on male rabbits. Drugs were administered orally. Theophylline administered as single dose [regimen I] or in concomitant administration with meloxicam following 7 days of meloxicam administration [regimen II]. Multiple dose study was conducted in three groups. The first one for meloxicam, the second for theophylline and the last for their co-administration. Assay of theophylline as well as meloxicam was performed by high performance liquid chromatography. The pharmacokinetic analysis was performed using the non-compartmental analysis. No significant differences between two regimens were found with respect to the main pharmacokinetic parameters of single dose as well as on steady state pharmacokinetic of theophylline according to the bioequivalence guidelines. However, study of within individual variability for Cmax and AUC0-inf revealed that there was a wide variation between individuals with respect to the effect of meloxicam on theophylline pharmacokinetics. The clinical significant of this work should be stressed on theophylline plasma concentration to be monitored in patients receiving concomitant meloxicam and theophylline therapy