Single dose bioequivalence study of alpha-methyldopa tablet formulations using a modified HPLC method.

BACKGROUND AND OBJECTIVE

The purpose of the present study was to compare the bioavailability of a new methyldopa (CAS 555-30-6) tablet formulation with that of a reference formulation in 12 healthy male subjects using a modified HPLC method.

METHODS

The study was designed as an open label, single-dose, randomized study with a cross-over design. Under fasting conditions, each subject received one 250-mg tablet orally as a single dose of a test or reference formulation on two treatment days. The treatment periods were separated by a one-week washout period. The blood samples were collected at different time points after each administration and determined using a rapid and reliable modified HPLC method. The method used was validated for specificity, accuracy, precision and sensitivity. The pharmacokinetic parameters (Cmax, AUC0-t, AUC0-infinity) were statistically compared by analysis of variance (ANOVA) for test and reference formulations.

RESULTS AND DISCUSSION

All validation criteria for the developed HPLC method were in acceptable range. The maximum plasma concentration (Cmax) of alpha-methyldopa was 270.3-1864.9 ng/ml for the test and 224.5-1585.6 ng/ml for the reference formulation. The mean AUC0-infinity of alpha-methyldopa was 2002.1-10614.8 and 2076.8- 9056.3 ng x h/ml for the test and reference formulation, respectively. The calculated 90% confidence intervals for the mean test/reference ratios of mentioned parameters were 92.48-115.94, and 88.82-101.13 which are in the bioequivalence range. The statistical tests did not show any statistical differences between formulations suggesting that methyldopa tablet of test and reference can be considered as bioequivalent preparations.

CONCLUSION

A rapid and reliable HPLC method with fluorescence detector was developed to analyze alpha-methyldopa in human plasma. Based on the obtained results the test formulation of alpha-methyldopa is bioequivalent to the reference formulation.