- benzoyl peroxide
This information is intended for use by health professionals
Adults and adolescentsApply a thin film to the whole of the affected area once daily preferably after washing and drying the skin. If excessive dryness or peeling occurs application should be temporarily interrupted as per physician instruction or patient tolerability.Maximum lesion reduction may be expected after approximately eight to twelve weeks of drug use. Continued use is normally required to maintain a clinical response.
Elderly PatientsThere are no specific recommendations for use in the elderly.
Paediatric PopulationSafety and effectiveness of topical benzoyl peroxide in children under the age of 12 has not been established.
FertilityThere are no data on the effect of topical benzoyl peroxide on fertility.
PregnancyThere are limited data on the use of topical benzoyl peroxide in pregnant women. Animal studies do not indicate direct or indirect harmful effects with respect to reproductive toxicity (see Section 5.3). No effects during pregnancy are anticipated since systemic exposure to benzoyl peroxide is very limited.However, benzoyl peroxide should be used during pregnancy only if the expected benefit justifies the potential risk to the foetus.
LactationPercutaneous absorption of benzoyl peroxide is very limited; however, it is not known whether benzoyl peroxide is excreted in human milk after topical application. Topical benzoyl peroxide should be used during lactation only if the expected benefit justifies the potential risk to the infant.If used during lactation, benzoyl peroxide should not be applied to the breast area to avoid accidental ingestion by the infant.
Symptoms and signsTopically applied benzoyl peroxide is not generally absorbed in sufficient amounts to produce systemic effects. Excessive application may result in severe irritation. In this event, discontinue use and wait until the skin has recovered.
TreatmentCold compresses can provide relief from irritation due to excessive application.Accidental ingestion of topical benzoyl peroxide should be managed clinically or as recommended by the National Poisons Centre, where available.
Mechanism of actionBenzoyl peroxide is a highly lipophilic oxidizing agent with bacteriocidal and keratolytic effects.
Pharmacodynamic effectsThe 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.
Absorption/Distribution/MetabolismBenzoyl peroxide is absorbed by the skin where it is metabolised to benzoic acid. Following topical application, less than 5% of the dose enters systemic circulation as benzoic acid.
EliminationBenzoyl peroxide is excreted as benzoic acid in the urine.
Carcinogenesis/mutagenesisBoth the carcinogenicity and photocarcinogenicity of benzoyl peroxide have been extensively assessed in both mice and hamsters, by various routes of administration, in studies ranging from 42 to 100 weeks in duration. The overall conclusion is that benzoyl peroxide is considered to be generally recognized as a neither carcinogenic nor photocarcinogenic and safe in topical acne products at a concentration of 2.5% to 10%.The genotoxicity of benzoyl peroxide was extensively assessed in vitro and in vivo. While in a few in vitro studies benzoyl peroxide showed weak mutagenicity, the overall genotoxicity profile did not indicate significant biological relevance.
Fertility and PregnancyIn a combined repeat- dose and reproduction/development toxicity study, benzoyl peroxide (250, 500 or 1,000 mg/kg/day) was administered orally to male rats for 29 days and female rats for 41-51 days. There were no treatment-related changes observed in the mating period, mating rate, conception rate, delivery rate, birth rate, pregnancy period, luteinization number, implantation number and the rate of losing embryos and foetuses after implantation. In pups, body weight was significantly decreased in the high-dose group. The no-observed-adverse-effect-level (NOAEL) for reproductive toxicities was considered to be 500 mg/kg/day.
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