[Examination of blood levels and urinary excretion of cefmetazole in the mature and immature neonates (author's transl)].

1. Cefmetazole was administered to mature and immature neonates for the purpose of treatment and prophylaxis of infections, and the blood level was examined. The mean blood level (moni-trol I standard) of cefmetazole after a single administration, 20 mg/kg intravenously, were 63.9 mcg/ml in 0 to 3 days old neonates and 57.4 mcg/ml in 4 to 7 days old neonates after 30 minutes, and 24.2 mcg/ml and 12.4 mcg/ml, respectively, after 6 hours. 2. The mean half-life of the blood level was 5.42 hours in 0 to 3 days old neonates and 2.55 hours in 4 to 7 old neonates. 3. The urinary excretion was varied, but approximately 80% of the administered dose seemed to be excreted during 0 to 12 hours. 4. Cefmetazole is seemed to be clinically effective by a single dose of 20 mg/kg giving twice daily in every 12 hours in 0 to 3 days old neonates, a dose of 20 mg/kg giving three times daily in every 8 hours in 4 to 7 days old infants, and a single dose of 20 mg/kg giving 3 to 4 times in every 6 to 8 hours in older than 8 days old neonates.