Cefcapene pivoxil hydrochloride (CFPN-PI), an ester cephem antibiotic, was orally given at a dose of 100 mg three times daily in patients with infection and soft stool or diarrhea, and its absorption was determined using the recovery ratio of 12-h urine pooled after the initial administration as an index. The primary endpoint, the recovery ratio of 12-h urine pooled after oral administration, could be evaluated in six of the eight patients finally gathered, and the mean value was 30.1 +/- 5.8%, which was not considered to differ from the mean value of 34.4 +/- 5.5% obtained in six healthy adult volunteers in the previous phase I study. Clinical efficacy in the eight patients was rated as very effective, effective, and ineffective in two, five, and one patients, respectively, with an effective ratio of 87.5% (7/8). Neither adverse drug reactions nor abnormal laboratory data were observed in any patient. These results indicate that CFPN-PI, at the routine oral dose, does not cause any problems in terms of absorption, efficacy, and safety when it is used in patients with infection and soft stool or diarrhea.