Synergistic activity of benzoyl peroxide and erythromycin

Benzoyl peroxide (BP) is the most widely used topical agent for acne since its introduction in the 1960s. Concomitant topical treatment of BP and erythromycin is stated to be superior to BP alone. However, no synergistic activity has been found with this combination. Instead, such combination therapies are hypothesized to gain their efficacy by the coupled action of two effective treatments. The antibiotic kills all susceptible bacteria and the BP eliminates the resistant strains.

The purpose was to compare radical production by BP alone and with various antibiotics to determine whether certain antibiotics increase radical formation by BP, as the antibacterial activity of BP may correlate with the amount of radicals it forms.

Polymerization of tetraethylene glycol dimethacrylate was used as a test of BP radical activity.

The results suggest that radical activity increases upon addition of certain antibiotics, such as erythromycin, to a solution of BP.

Radical activity of BP in tetraethylene glycol dimethacrylate is increased when tested in consort with several antibiotics, such as the macrolides. We propose that the tertiary amines contained on certain antibiotics are responsible for catalysis of BP radical formation. If increased radical formation correlates with enhanced biological effect, then these data reveal the possibility of a biological synergism in mixtures of BP and antibiotics. An understanding of the mechanism of catalysis of BP radical formation by antibiotics may lead to the discovery of improved treatments for acne.