Failure of once-daily penicillin V therapy for streptococcal pharyngitis.

To determine if a single daily dose of penicillin V would be effective in the treatment of group A beta-hemolytic streptococcal (GABHS) pharyngitis, 154 patients with GABHS pharyngitis were randomly assigned to receive 750 mg of penicillin V once daily for ten days or 250 mg of penicillin V three times daily for ten days. The two regimens were comparable in their ability to eradicate GABHS from the upper respiratory tract in 18 to 24 hours and in their impact on the clinical course of the disease. However, a bacteriologic treatment failure occurred in six (8%) of the 76 patients in the three-times-daily group and in 16 (22%) of the 74 patients in the once-daily group. These findings support the current recommendation that penicillin V be given in two or more divided doses for a full ten days for the treatment of GABHS pharyngitis.