Comparative bioavailability of two digoxin formulations: determination in human plasma by microparticle enzyme immunoassay

The present study was performed to compare the bioavailability of two digoxin 0.25 mg tablet formulation in 30 volunteers of both sexes. The study was conducted open with randomized two period crossover design and a three-week washout period. Plasma samples were obtained over a 144 h interval. Digoxin concentrations were analyzed by a validated microparticle enzyme immunoassay with optical detection by fluorescence. Bioequivalence between the products was determined by calculating 90 % confidence intervals (90 % I.C) for the ratio of AUC_0-72h and C_max values for the test and reference products, using logarithmic transformed data. The 90 % confidence intervals were 86.98-118.33 %, and 84.52–98.76 %, respectively. Since the 90 % confidence intervals for C_max and AUC_0-72h were within the 80-125 % interval proposed by Food and Drug Administration, it was concluded that the two Digoxin formulations are bioequivalent in their rate and extent of absorption. Colegio de Farmacéuticos de la Provincia de Buenos Aires