Impact of pharmaceutical dosage forms on the pharmacokinetics of roxithromycin in healthy human volunteers

Objectives: The impact of two different pharmaceutical preparations on the pharmacokinetics of roxithromycin was investigated in healthy human volunteers. Methods: The degradation kinetics and products of roxithromycin were investigated in simulated gastric fluid and simulated intestinal fluid. Two oral dosage forms of roxithromycin were employed: enteric-coated pellets and dispersible tablets. Results: The degradation half-time of roxithromycin in simulated gastric fluid was 0.23 h, and three main degradation products were characterized. In contrast, roxithromycin was stable in simulated intestinal fluid and remained unchanged after a 1.00h incubation. The roxithromycin enteric-coated pellets exhibited higher bioavailability and a more potent serum antibacterial activity than the dispersible tablets. Conclusions: The type of oral dosage forms of roxithromycin altered its pharmacokinetics. Whether or not this affects the in vivo antibacterial efficacy requires further study.