Sulfonamide Administration in Newborn and Premature Infants

All newborn infants, both full-term and premature, who received, on the first day of life, a single subcutaneous injection of sulfadiazine, 100 mg./kg. body weight, maintained a satisfactory concentration of sulfonamide in the blood for 48 hours thereafter. This therapeutic concentration was subsequently maintained by single 24-hour doses of 50 mg./kg. body weight given subcutaneously, or by single 12-hour doses of 50 mg./kg. body weight given orally. A therapeutic concentration in the blood is generally considered to be a minimum of 5 mg./100 ml. Based on these data the authors recommend the following sulfonamide dosage schedules: A. Infants under 24 hours of age, full-term and premature: 1) subcutaneous sodium sulfadiazine, initial dose 100 mg./ kg. body weight, followed in 48 hours by 50 mg./kg. body weight as a single dose, and repeated each 24-hour period thereafter, or 2) subcutaneous sodium sulfadiazine, initial dose 100 mg./kg. body weight, followed in 48 hours by an oral preparation in the amount of 50 mg./kg. as a single oral dose, each 12-hour period thereafter. (This was evaluated only in full-term infants.) B. Premature infants over 48 hours of age. (This dosage schedule is comparable to that generally accepted for older infants and children): 1) subcutaneous sodium sulfadiazine, initial dose 100 mg./kg. body weight, followed in 12 hours by 50 mg./kg. body weight as a single dose, each 12-hour period thereafter, or 2) oral sulfonamide preparation, initial dose 100 mg./kg. body weight, followed in 12 hours by 50 mg./kg. body weight as a single dose, each 12-hour period thereafter.