Comparative Bioavailability of Alpha-Methyldopa normal and film tablet formulations after single oral administration in healthy volunteers

In a single dose, randomized, cross-over study, with one week of wash-out p eriod, the relative bioavailability of Dopegyt(R) tablets containing 250 mg alpha-methyldopa (AMD) and Presinol(R) film tablets with identical active ingredient content was examined in 24 healthy volunteers. Since technologically two completely different preparations (a film-tablet and a non-film-tablet) having significantly different in vitro dissolution were to be compared, both preparations were compared to a third one, AMD so lution (Dopegyt solution) with 250 mg/50 ml concentration. Plasma concentra tions of the drug were measured for 24 hours post-dose, applying HPLC with fluorometric detection. Pharmacokinetic parameters calculated from individu al data (AUC(o-infinity), AUC(o-t), C-max, C-max/AUC(o-infinity), t(max)) w ere evaluated statistically. Wilcoxon's nonparametric test and the four-way variance analysis could not detect any significant difference at the usual a=95% probability level in these pharmacokinetic parameters of the two tab let preparations. For AUC(o-infinity) at the 90% probability level, the con fidence interval was 0.883-1.237 (with an estimated geometric mean of 1.045 ), for the test/reference ratio of Dopegyt(R) and Presinol(R) tablets, thus the two preparations proved to be bioequivalent. The relative bioavailabil ity of Dopegyt (test preparation) and Presinol(R) (reference preparation) c alculated from the AUC(o-infinity) values was 116.7 +/- 56.7% that also con firmed bioequivalence. The results of all the applied statistical tests sug gest that Dopegyt and Presinol can be considered as bioequivalent preparati ons.