New Developments in OTC Acne Treatment
Hydroxy acids, such as glycolic acid, have been used as nonmonographed ingredients in acne products, however, no treatment claims can be made. The efficacy of glycolic acid in treating acne is related to the free acid concentration. The free acid is able to dissolve the ionic bonds between the corneocytes forming the stratum corneum. This desquamation can remove the comedonal plugs, however, the water-soluble glycolic acid cannot enter the oily milieu of the pore. For this reason, the monographed ingredient salicylic acid is a much better comedolytic.
Retinoids are used in both prescription and OTC acne treatments. The recent transition of one particular retinoid, adapalene, from a prescription-only medication to an OTC medication has increased the overall efficacy of the OTC acne market, because adapalene is so effective at treating the microcomedone. Other nonmonographed retinoids, such as retinol, can be absorbed by keratinocytes and reversibly oxidized into retinaldehyde. Retinaldehyde is irreversibly converted into all-trans retinoic acid, known as tretinoin, a potent prescription retinoid. Thus, retinol has been shown to be 20 times less potent than topical tretinoin, but exhibits greater penetration than tretinoin and is found in some acne preparations as an inactive ingredient.9
Tea Tree Oil
Botanicals can also be used as an inactive ingredient in acne formulations. Tea tree oil, renowned for its antibacterial properties, is the most common herbal essential oil used for acne treatment. It is extracted from the leaves of the Australian tree Melaleuca alternifolia.10 Tea tree oil has been found to be as effective as 5% benzoyl peroxide based on a reduction in comedones and inflammatory acne lesions, however, the onset of action was slower for tea tree oil.11 Another randomized, double-blind, placebo-controlled study of 60 individuals with mild to moderate acne found 5% topical tea tree oil produced a statistically significant reduction in total lesion count and acne severity index as compared with a placebo.12
Tea tree oil is a known cause of allergic contact dermatitis, however. An Italian study of 725 participants patch tested with undiluted, 1% and 0.1% tea tree oil found that 6% of participants experienced a positive reaction to undiluted tea tree oil, 1 participant experienced an allergic reaction to 1% tea tree oil, and no participants experienced a reaction to the 0.1% dilution.13
Vitamins and Minerals
There has been a resurgence of nonmonographed vitamins and minerals for acne treatment. Zinc salts are bacteriostatic to P acnes, and orally ingested as a homeopathic acne therapy.14 Oral zinc has also been combined with nicotinamide orally for the treatment of acne through a reduction in inflammation by inhibiting leukocyte chemotaxis, lysosomal enzyme release, and mast cell degranulation.15 An OTC nicotinamide-containing vitamin preparation has been shown to produce acne improvement in 8 weeks.16 Topically, nicotinamide 4% was shown to be comparable to clindamycin gel 1% in the treatment of moderate acne.17
Prebiotics and Postbiotics
The newest area of nonmonographed oral and topical acne formulations is the use of prebiotics and postbiotics. Prebiotics are indigestible food substances that promote the growth of healthy bacteria in the gut. There is said to be a gut-skin connection, implying that acne could be improved by modifying the microbiome, which are the bacterial inhibitants of the gut. Injesting prebiotics might normalize the gut microbiome and improve acne.
Postbiotics, on the other hand, are live bacteria that can be applied topically or orally consumed to improve the skin microbiome.18 Lactobacillus acidophilus cultures are used for this purpose. It is thought that microbiome alternations may influence systemic inflammation, oxidative stress, and glycemic control, among other things. Intestinal permeability may be amplified in acne, so the consumption of oral postbiotics could help.19 Refrigerated postbiotic preparations may also create more microbiome diversity, a common finding in normal skin.
Spotting a Trend
After antiaging, acne has to be the biggest expanding skin product frontier, and the growth of the OTC acne market is sure to continue. With acne products now becoming part of boutique spa lines, physician dispensed skin care, cosmetic company offerings, and store brand products, dermatologists would do well to educate themselves about the range of new products available, so they can better advise their patients.
Dr Draelos is a research and clinical board-certified dermatologist and a fellow of the American Academy of Dermatology. She is in solo private practice in High Point, NC, and a consulting professor of dermatology at Duke University, and has authored 14 books. She is also the founder of Dermatology Consulting Services, PLLC, to initiate and perform research in aging skin, acne, rosacea, psoriasis, atopic dermatitis, actinic keratoses, eczema, and aesthetic procedures in the cosmetic, OTC drug, and pharmaceutical arenas.
Disclosure: The author reports no relevant financial relationships.
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