A comparative evaluation of the pharmacokinetics of different forms of benzathine benzylpenicillin]

Comparative randomized opened pharmacokinetic evaluation of benzathine benzylpenicillin in three dosage forms was performed. Benzathine benzylpenicillin was used as extencilline (2.4 million U or 1.2 million U, "Rh?ne-Poulenc Rorer", France) and as bicillin-5 (1.5 million U, "Synthesis" Russia). 33 patients were included in investigation (23 women and 10 men aged 16-60 years). 25 persons had verified rheumatism without blood circulation failure signs, 4--had chronic tonsillitis and 4 were healthy volunteers. Benzylpenicillin concentration was estimated by microbiology test in blood samples taken at 1, 3, 24 hours and 7, 14 and 21 days after intramuscular drug injection. After 2.4 million U extencilline injection (12 patients) its concentration, was at the inhibition level for beta-hemolytic streptococcus group A (25 ng/ml) for 3 weeks-period in 83.3 per cent of patients. After 1.2 million U extencilline injection (10 patients) or 1.5 million U bicillin-5 injection (12 patients) the above mentioned concentration was achieved on the 21st day in 30 and 0 per cent of patients respectively. Thus the treatment with benzathine benzylpenicillin at the 1.2 million U dose in the form of extencilline or bicillin-5 doesn't provide adequate antistreptococcal concentration in blood in prolonged period and is not suitable for correct rheumatism prophylaxis in adult patients.