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 Skeletal formula (top) Ball-and-stick model (bottom) | |
| Clinical data | |
|---|---|
| Trade names | Benzac, Panoxyl, others |
| Other names | benzoperoxide, dibenzoyl peroxide (DBPO), BPO |
| AHFS/Drugs.com | Professional Drug Facts |
| MedlinePlus | a601026 |
| License data | |
| Routes of administration | Topical |
| ATC code | |
| Legal status | |
| Legal status | |
| Identifiers | |
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| CAS Number | |
| PubChemCID | |
| DrugBank | |
| ChemSpider | |
| UNII | |
| KEGG | |
| ChEBI | |
| ChEMBL | |
| CompTox Dashboard(EPA) | |
| ECHA InfoCard | 100.002.116 |
| Chemical and physical data | |
| Formula | C14H10O4 |
| Molar mass | 242.230 g·mol−1 |
| 3D model (JSmol) | |
| Density | 1.334 g/cm3 |
| Melting point | 103 to 105 °C (217 to 221 °F) decomposes |
| Solubility in water | poor mg/mL (20 °C) |
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| Data page | |
| Benzoyl peroxide (data page) | |
Benzoyl peroxide is achemical compound (specifically, anorganic peroxide) with thestructural formula(C6H5−C(=O)O−)2, often abbreviated as (BzO)2. In terms of its structure, the molecule can be described as twobenzoyl (C6H5−C(=O)−, Bz) groups connected by aperoxide (−O−O−). It is a white granular solid with a faint odour ofbenzaldehyde, poorly soluble in water but soluble inacetone,ethanol, and many other organic solvents. Benzoyl peroxide is anoxidizer, which is principally used in the production ofpolymers.[5]
Benzoyl peroxide is mainly used in production ofplastics[5][6] and for bleachingflour,hair,plastics andtextiles.[7][8]
As ableach, it has been used as amedication and awater disinfectant.[6][8]
As a medication, benzoyl peroxide is mostly used to treatacne, either alone or in combination with other treatments.[9] Some versions are sold mixed withantibiotics such asclindamycin.[10][11] It is on theWorld Health Organization's List of Essential Medicines.[12] It is available as anover-the-counter andgeneric medication.[13][10] It is also used indentistry forteeth whitening. In 2021, it was the 284th most commonly prescribed medication in the United States, with more than 700,000 prescriptions.[14][15]
Benzoyl peroxide was first prepared and described byJustus von Liebig in 1858.[16]Donald Holroyde HeyFRS[17] (12 September 1904 – 21 January 1987) was aWelsh organic chemist who inferred that the decomposition of benzoyl peroxide generatedfree phenyl radicals.[18][19]
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The original 1858 synthesis by Liebig reactedbenzoyl chloride withbarium peroxide,[16] a reaction that probably follows this equation:
Benzoyl peroxide is usually prepared bytreatinghydrogen peroxide withbenzoyl chloride underalkaline conditions.
The oxygen–oxygen bond in peroxides is weak. Thus, benzoyl peroxide readily undergoeshomolysis (symmetrical fission), formingfree radicals:
The symbol• indicates that the products are radicals; i.e., they contain at least one unpaired electron. Such species are highly reactive. The homolysis is usually induced by heating. Thehalf-life of benzoyl peroxide is one hour at 92 °C. At 131 °C, the half-life is one minute.[21]
In 1901, it was observed that the compound made the tincture ofguaiacum tincture turn blue, a sign ofoxygen being released.[22] Around 1905, Loevenhart reported on the successful use of benzoyl peroxide to treat various skin conditions, includingburns, chronicvaricose leg tumors, andtinea sycosis. He also reported animal experiments that showed the relatively low toxicity of the compound.[23][7][24]
Treatment with benzoyl peroxide was proposed for wounds in 1929, and forsycosis vulgaris andacne varioliformis in 1934.[24] However, preparations were often of questionable quality.[7] It was officially approved for the treatment of acne in the US in 1960.[7]
Benzoyl peroxide is mainly used as aradical initiator to inducechain-growth polymerization reactions,[5] such as forpolyester andpoly(methyl methacrylate) (PMMA) resins anddental cements andrestoratives.[25] It is the most important among the various organicperoxides used for this purpose, a relatively safe alternative to the much more hazardousmethyl ethyl ketone peroxide.[26][27] It is also used in rubber curing and as a finishing agent for someacetate yarns.[25]
Benzoyl peroxide is effective for treatingacne lesions. It does not induceantibiotic resistance.[28][29] It may be combined withsalicylic acid,sulfur,erythromycin orclindamycin (antibiotics), oradapalene (a syntheticretinoid). Two commoncombination drugs includebenzoyl peroxide/clindamycin andadapalene/benzoyl peroxide,adapalene being a chemically stable retinoid that can be combined with benzoyl peroxide[30] unliketezarotene andtretinoin. Combination products such as benzoyl peroxide/clindamycin and benzoyl peroxide/salicylic acid appear to be slightly more effective than benzoyl peroxide alone for the treatment of acne lesions.[29] The combinationtretinoin/benzoyl peroxide was approved for medical use in the United States in 2021.
Benzoyl peroxide for acne treatment is typically applied to the affected areas in gel, cream, or liquid, in concentrations of 2.5% increasing through 5.0%, and up to 10%.[28] No strong evidence supports the idea that higher concentrations of benzoyl peroxide are more effective than lower concentrations.[28]
Classically, benzoyl peroxide is thought to have a three-fold activity in treating acne. It is sebostatic, comedolytic, and inhibits growth ofCutibacterium acnes, the mainbacterium associated with acne.[28][31] In general, acne vulgaris is a hormone-mediated inflammation of sebaceous glands and hair follicles. Hormone changes cause an increase in keratin and sebum production, leading to blocked drainage.C. acnes has many lytic enzymes that break down the proteins and lipids in the sebum, leading to an inflammatory response. The free-radical reaction of benzoyl peroxide can break down the keratin, therefore unblocking the drainage of sebum (comedolytic). It can cause nonspecific peroxidation ofC. acnes, making it bactericidal,[7] and it was thought to decrease sebum production, but disagreement exists within the literature on this.[31][32]
Some evidence suggests that benzoyl peroxide has an anti-inflammatory effect as well. In micromolar concentrations it prevents neutrophils from releasing reactive oxygen species, part of the inflammatory response in acne.[32]
Application of benzoyl peroxide to the skin may result in redness, burning, and irritation. This side effect is dose-dependent.[9][13]
Because of these possible side effects, it is recommended to start with a low concentration and build up as appropriate, as the skin gradually developstolerance to the irritation caused by the medication. Skin sensitivity typically resolves after a few weeks of continuous use.[32][33] Irritation can also be reduced by avoiding harsh facial cleansers and wearingsunscreen prior to sun exposure.[33]
One in 500 people experiencehypersensitivity to benzoyl peroxide and are liable to experience burning,itching, crusting, and possiblyswelling.[34][35] About one-third of people experiencephototoxicity under exposure toultraviolet (UVB) light.[36]
In the US, the typical concentration for benzoyl peroxide is 2.5% to 10% for bothprescription andover-the-counter drug preparations that are used in treatment for acne.[37]
Benzoyl peroxide is used in dentistry as atooth whitening product.[38]
Benzoyl peroxide is potentiallyexplosive[39] like otherorganic peroxides, and can cause fireswithout external ignition. The hazard is acute for the pure material, so the compound is generally used as a solution or a paste. For example, cosmetics contain only a small percentage of benzoyl peroxide and pose no explosion risk.
Benzoyl peroxide breaks down in contact with skin, producingbenzoic acid and oxygen, neither of which is very toxic.[40]
Thecarcinogenic potential of benzoyl peroxide has been investigated. A 1981 study published in the journalScience found that although benzoyl peroxide is not a carcinogen, it does promote cell growth when applied to aninitiated tumor. The study concluded, "caution should be recommended in the use of this and other free radical-generating compounds".[41]
A 1999IARC review of carcinogenicity studies found no convincing evidence linking benzoyl peroxide acne medication toskin cancers in humans. However, some animal studies found that the compound could act as a carcinogen and enhance the effect of known carcinogens.[25]
Benzoyl peroxide can break down into carcinogenbenzene at temperatures above 50 °C.[42][43]
In a 1977, study using a human maximization test, 76% of subjects acquired a contact sensitization to benzoyl peroxide. Formulations of 5% and 10% were used.[44]
The USNational Institute for Occupational Safety and Health has developed criteria for a recommended standard for occupational exposure to benzoyl peroxide.[45]
Contact withfabrics orhair, such as from still-moist acne/pimple medication, can cause permanent color dampening almost immediately. Even secondary contact can cause bleaching, for example, contact with a towel that has been used to wash off benzoyl peroxide-containing hygiene products.[46]
