PHARMACOKINETICS OF CEFETAMET IN PLASMA AND SKIN BLISTER FLUID

Cefetamet pivoxil is an oral cephalosporin with enhanced affinity for the target penicillin-binding proteins 1 and 3 and an increased stabil ity to beta-lactamases compared with older cephalosporins, such as cef alexin or cefaclor. The pharmacokinetics of cefetamet pivoxil was dete rmined after the seventh and final dose of 500 mg of cefetamet pivoxil in eight healthy volunteers. Concentrations in plasma and cantharidin -induced skin blister fluid were determined by a high-performance liqu id chromatography method, In addition, protein binding was assessed. C -max was 4.8 +/- 1.7 mu g/ml in skin blister fluid and 5.1 +/- 2.1 mu g/ml in plasma, T-max was delayed in skin blister fluid compared with plasma (3.9 +/- 1 versus 2.8 +/- 0.8 h; P < 0.001), and t(1/2) was lon ger in skin blister fluid than in plasma (3.1 +/- 0.5 versus 2.3 +/- 0 .3; P < 0.005). The mean percent penetration into cantharide blister f luid was 129% +/- 24% when measured as total drug and 149% +/- 28% whe n measured as free drug (P < 0.001). These data suggest that cefetamet has an excellent penetration into inflammatory interstitial fluid.