A five-day course of penicillin appears to be as effective as a 10-day course for pharyngotonsillitis caused by group A streptococci, a study finds.

Swedish researchers hypothesised that 800mg penicillin V given four times daily for five days would be noninferior to the recommended dose of 1000mg penicillin V given three times daily for 10 days.

This was based on the idea that the efficacy of beta-lactam antibiotics depended on time above the minimum inhibitory concentration of the unbound drug concentration in serum.

They carried out a randomised, open-label, noninferiority trial of 433 patients with pharyngotonsillitis caused by group A streptococci.