[Laboratory and clinical studies on SY5555 in pediatrics].

Laboratory and clinical studies were performed on SY5555, the first penem oral antibiotic developed in Japan, in the pediatric field. The following results were obtained. 1. Antibacterial activities of the drug against 42 strains of Streptococcus pneumoniae clinically isolated in 1993 were compared to those of 13 other drugs mainly composed of beta-lactam preparations. Minimum inhibitory concentration (MIC) values of SY5555 were below 0.39 micrograms/ml for all strains examined, thus the drug showed an excellent activities against benzylpenicillin (PCG)-resistant strains as well. When the antibacterial effects of individual drugs were compared using MIC50 and MIC90 as indices, SY5555 was the most effective against PCG-sensitive strains and similar to cefazolin (CEZ), cefotaxime (CTX), cefuzonam (CZON), amoxicillin (AMPC) and imipenem (IPM). It also showed excellent antibacterial effects against moderately PCG-resistant strains, and the activities were similar to IPM. Activities of SY5555 on highly PCG-resistant strains were similar to those of CTX, CZON and IPM. 2. SY5555 at a dose of 5 mg/kg or 10 mg/kg was administered to 16 pediatric patients in the fasting state or after meal to examine its plasma concentration and urinary excretion rate. The fecal excretion was measured in 5 affected children treated with this drug. When the drug at a dose of 5 mg/kg was administered to 11 older children, 5 with ages 5-12 years and 6 with ages 10-13 years in the fasting state and after meal, respectively. Peak plasma levels were reached at 1 hour after administration in the two groups, and they were 0.93 +/- 0.25 and 2.44 +/- 1.25 micrograms/ml, respectively. The plasma levels then decreased gradually with half-lives of 1.95 +/- 1.09 and 0.72 +/- 0.21 hours, respectively. Urinary recovery rates in the first 6 hours after administration were 1.98 +/- 0.82 and 4.13 +/- 1.40%, respectively. In 3 cases (6-9 years) treated with the drug at a dose of 10 mg/kg after meal, a peak of 1.58 +/- 0.81 micrograms/ml appeared 1 hour after administration with a half-life of 1.08 +/- 0.30 hours and with the urinary recovery rate in the first 6 hours after administration of 3.46 +/- 1.03%. When the drug at a dose of 10 mg/kg was administered to 2 infants (2-3 months post partum) after meal, a peak plasma level of 3.74 micrograms/ml appeared 1 hour after administration with a half-life of 1.19 hours.(ABSTRACT TRUNCATED AT 250 WORDS)