Benzathine penicillin, metronidazole and benzyl penicillin in the treatment of tetanus: a randomized, controlled trial.

Penicillin, the drug of choice in tetanus, may potentiate the effect of tetanus toxin by inhibiting the type-A (GABAA) receptor for gamma-amino-n-butyric acid. Metronidazole has therefore been suggested as an alternative. Intramuscular benzathine penicillin (1.2 million units as a single dose; N=56), enteral metronidazole (600 mg every 6 h for 10 days; N=55) and intravenous benzyl penicillin (2 million units every 4 h for 10 days; N=50) were therefore compared, in a randomized, controlled trial, among patients with all grades of tetanus. On presentation, the three treatment groups were similar in terms of age and sex distributions, immune statuses, durations of illness, and their APACHE-II scores and Ablett's grades of tetanus. Of the patients given benzathine penicillin, 36 required tracheostomy, 10 neuromuscular blockade, and 23 mechanical ventilation; the corresponding numbers for the metronidazole (34, 12 and 18, respectively) and benzyl-penicillin groups (39, 12 and 25, respectively) were similar (P>0.10). The incidences of dysautonomia and nosocomial pneumonia and the numbers of in-hospital deaths (26 with benzathine penicillin, 19 with metronidazole and 22 with benzyl penicillin; P=0.392) were also similar in each treatment arm. The length of the hospital stay was longer in the patients receiving benzyl penicillin than in the benzathine-penicillin or metronidazole groups, with means (S.D.) of 21.9 (15), 16.9 (11) and 19.9 (15) days, respectively, but the difference was not statistically significant (P=0.09). Although the three antibiotic regimens investigated appear equally effective, benzathine penicillin offers the convenience of a single, intramuscular injection instead of the 10 days of therapy needed with the other two drugs.