Loracarbef is an investigational oral antibiotic but its pharmacokinetics have not been studied after multiple oral doses in pediatric patients. The pharmacokinetics of loracarbef were determined in 18 pediatric patients after multiple oral doses. 8 patients with streptococcal pharyngitis received 7.5 mg/kg every 12 h, and 10 patients with otitis media were given 15 mg per kg every 12h. Multiple blood and urine samples were collected to measure loracarbef concentrations. In patients with streptococcal pharyngitis, the mean maximum serum concentration (Cmax), the time to achieve maximum concentration (Tmax), area under the serum concentration-time curve (AUC) and elimination half-life (t1/2) were 10.6 +/- 3.6 mcg/ml, 0.78 +/- 0.21 h, 21.4 +/- 7.2 mcg.h/ml, and 1.2 + 0.4 h, respectively. The mean Cmax, Tmax, AUC and t1/2 were 18.0 +/- 5.4 mcg/ml, 0.83 +/- 0.44 h, 35.6 +/- 9.4 mcg.h/ml, and 1.1 +/- 0.5 h, respectively, in patients with otitis media. The Cmax exceeded the minimum inhibitory concentration of common susceptible pathogens causing pharyngitis and otitis media by severalfold. Nearly 60% of the dose was excreted unchanged in the urine during the dosage interval. The pharmacokinetics were independent of dose. Loracarbef was well tolerated in all patients. These data suggest that loracarbef may be used safely at doses of 7.5 mg/kg every 12 h in pediatric patients with streptococcal pharyngitis and 15 mg/kg every 12 h in those with otitis media.