Benzoyl peroxide

Benzoyl peroxide is a highly lipophilic, oxidising agent with keratolytic and bacteriocidal effects.

The effectiveness of benzoyl peroxide in the treatment of acne vulgaris is primarily attributable to its antibacterial activity, especially with respect to Propionibacterium acnes. The antibacterial activity of benzoyl peroxide is due to the release of active or free-radical oxygen capable of oxidising bacterial proteins. Benzoyl peroxide is also believed to be effective in the treatment of acne on account of its anti-inflammatory and mild keratolytic properties.

Radio-labelled studies have shown that absorption of benzoyl peroxide through the skin can only occur following its conversion to benzoic acid.

Following topical application, less than 5% of the dose enters systemic circulation as benzoic acid.

There is no evidence of any tissue accumulation. There is no evidence that cutaneous application of the proposed clinical doses of benzoyl peroxide should be associated with any systemic adverse reactions in humans.

The majority of the penetrated benzoyl peroxide is converted into benzoic acid which after absorption into the systemic circulation is rapidly eliminated by the kidney.

In animal toxicity studies, benzoyl peroxide was well tolerated when applied topically.

Although high doses of benzoyl peroxide have been shown to induce DNA strand breaks, the available data from other mutagenicity studies, carcinogenicity studies and a photo co-carcinogenicity study indicate that benzoyl peroxide is not a carcinogen or a photocarcinogen.

Benzoyl peroxide (250, 500, or 1000 mg/kg/day) administered orally to male rats for 29 days and female rats for 41-51 days did not affect mating period, mating rate, conception rate, delivery rate, birth rate, pregnancy period, luteinisation number, implantation number and the rate of losing embryos and fetuses after implantation. In pups, body weight was significantly decreased in the high-dose group.