CONCENTRATION OF PENICILLIN IN THE SERUM FOLLOWING INTRAMUSCULAR ADMINISTRATION OF BENZATHINE PENICILLIN G TO CHILDREN WITH INACTIVE RHEUMATIC FEVER

Abstract

Ninety-six children between the ages of 4 and 20 years with inactive rheumatic fever received 1,200,000 units of benzathine penicillin G every 28 days by intramuscular injection and were studied from the standpoint of effective and consistent concentrations of penicillin in the serum. The concentrations of penicillin in the serum could be determined with certainty in 81% of the specimens; concentrations ranged from 0.002 to 0.125 unit/ml. The mean concentration of penicillin reached in the serum of females was three times higher than in males. The concentration of penicillin in the serum of females increased with age and weight from the tenth to the seventeenth years. No such increase was observed in the sera of males in relation to age and weight. The differences in concentration of penicillin reached in the sera of the two sexes from 12 through 17 years of age were statistically significant (p less than 0.01). No significant difference in concentration of penicillin in the serum was found in comparing obese and thin girls of 10 through 15 years of age. The explanation for the differences between the two sexes is not apparent. During the period of the study, 491 swabs from the nose and throat yielded only one positive culture for beta hemolytic streptococcus of group A; this organism could not be typed and was not associated with an increase in the titer of antistreptolysin O. One other patient had a significant rise in antibody titer, but there was no antecedent positive culture for streptococcus. There were no recurrences of rheumatic fever.