Single-dose pharmacokinetics of macrocrystalline nitrofurantoin formulations

The pharmacokinetics of macrocrystalline formulations of nitrofurantoin (50 mg and 150 mg) were studied after single dose administration in 10 healthy male volunteers, using a cross-over study design. The total estimation of the pharmacokinetic data was calculated simultaneously from all of the single values, using a direct search procedure based on an open two-compartment-model (with additional 2 first-order input steps for one of the 150 mg formulations). Analysis showed that the relevant pharmacokinetic parameters for the formulations studied were in comparable ranges; however, the terminal elimination half-lives, 1.2 h and 1.7 h, were 3 to 4 times longer in comparison to those currently reported in the literature. The marked discrepancy in these findings is discussed and a review of the current data on the elimination kinetics of nitrofurantoin is recommended.