Cefodizime is a third generation cephalosporin for parenteral use. The pharmacokinetics of this cephem antibiotic were determined in serum and skin suction blister fluid (SBF) after intravenous (i.v.) or intramuscular (i.m.) administration of a single 1 g dose in 8 adult patients with normal renal and hepatic function who volunteered for the study. The concentration versus time curve showed a slower elimination rate from the extravascular compartment: the half-lives were 4.4+/-0.5 and 5.4+/-0.4 hours after i.v. and i.m. route respectively. The relatively long elimination half-life in SBF with a mean residence time of about 8 hours allows the use of cefodizime once-a-day for the treatment of infections due to sensitive pathogens.