Pharmacologic and clinical comparison of cefaclor in immediate-release capsule and extended-release tablet forms.

A new controlled-delivery, extended-release 500-mg formulation of cefaclor that is administered twice daily may improve patient compliance compared with the older, immediate-release 250-mg formulation that is administered three times daily. When the extended-release tablet is administered with food, peak plasma cefaclor concentrations are achieved about 2.5 hours after the dose compared with about 1 hour after a dose with the immediate-release capsule. However, the two formulations have an equivalent extent of absorption and equivalent pharmacokinetics after absorption. Cefaclor has retained its excellent in vitro activity against the pathogens most commonly associated with acute exacerbations of chronic bronchitis, namely, Haemophilus influenzae, Moraxella catarrhalis, and Streptococcus pneumoniae. Clinical trials show similar efficacy of the two formulations in patients with acute exacerbations of chronic bronchitis caused by these organisms, but for this indication a 7-day regimen may be used with the extended-release 500-mg formulation compared with a 10-day dosing regimen with the 250-mg capsule. The shorter course of treatment with the new formulation may also improve patient compliance.