Abstract

The bioavailability of nitrifurntoin was evaluated in eight healthy volunteers, in a crossover fashion, after administration of 100-mg dose of the drug in water-in-oil-in-water (W/O/W) emulsions with and without viscosity imparting agents. The bioavailabilitiy of the drug was assessed from urinary excretion data of the unchanged drug. The extent of absorption,maximum excretion rate and period of minimum effective urine concentration were all significantly higher (p < 0.05) in the w/o/w emulsion with viscosity imparting agents compared with the corresponding values for the reference w/o/w emulsion (containing no viscosity agent). From these results, it is suggested that the bioavailability and therapeutic efficacy of nitrofurantoin administered in w/o/w formulations could be further enhanced by increasing the viscosity of the formulation. Also the nature of the viscosity imparting agent plays a significant role in determining the extent of improvement of nitrofurantoin absorption.