Evaluation of an oral prolonged-release antibiotic formulation.

The antibiotic cephalexin was formulated as an oral prolonged-release tablet and evaluated by in vitro dissolution testing as well as in vivo in 10 human subjects. Comparisons were made of the time course of the blood levels among the prolonged-release formulation, the commercially available capsule, and intravenous administration. Even though lower peak blood levels were attained in the prolonged-release tablet, absorption continued for at least 6 hr. Comparison with in vitro dissolution data showed that absorption was dissolution rate limited. Bioavailability comparisons showed that the prolonged-release formulation was completely available, as was the commercial oral capsule.