Pharmacokinetics of roxithromycin and influence of H2-blockers and antacids on gastrointestinal absorption.

The pharmacokinetics of roxithromycin (300 mg orally) and the influence of the antacid aluminum magnesium hydroxide and the H2-blocker ranitidine on bioavailability of roxithromycin in ten healthy volunteers were studied. Pharmacokinetics after a single dose of roxithromycin were characterized by high peak serum levels (9.1 +/- 2.1 mg/l) and a long elimination half-life (7.2 +/- 2.5 h), resulting in a large area under the curve (116.9 +/- 32.7 mg h/l). High inter- and intraindividual variations were found for both the absorption time and the elimination half-life. The bioavailability of roxithromycin was not affected by coadministration with antacids or ranitidine.