Serum penicillin concentration in rheumatic patients on benzathine penicillin prophylaxis

ABSTRACT

The study included 40 selected patients with a documented history of rheumatic fever or clinical rheumatic heart disease [RHD]. They were 24 males and 16 females; aged 6-14 yrs. Group 1 included 20 patients on regular tri-weekly prophylaxis with benzathine penicillin [BPG] 1.2 mega units I.M., group 2 included 20 patients on irregular prophylaxis. Serum penicillin concentration was estimated at the end of the first, second and third weeks after administration, by the agar-diffusion microbiological assay. All cases in both groups had adequate serum panicillin levels at the end of the second week. However, at the end of the third week, 45% of patients in group 1, and 75% in group 2 had serum penicillin levels < 0.03 micro g/ml; [minimal therapeutic level = 0.03 micro g/ml]. None of patients in group I showed any rheumatic activity, while 5/9 from group 2 [55.5%] showed laboratory evidence of activity. Cardiac affection detected in 8/20 patients in group I remained stationary during a 5 years follow up, while 19/20 of group 2 patients had established valvular disease by the end of this period. This indicates the greater impact of rheumatic recurrences, clinical or subclinical, on progress of cardiac affection due to non compliance. We concluded that triweekly regimen of BPG is adequate provided that patient's compliance is assured