Topical treatment in acne: current status and future aspects

Abstract

During the last 20 years, the number of topical and systemic drugs for the treatment of acne vulgaris has been enriched. Topical drugs on the one hand have been newly discovered or further developments of already available agents such as in the group of retinoids or galenic formulation have improved efficacy or local tolerance. Topical retinoids are a mainstay in acne treatment since 1962. All-trans retinoic acid was the first and is still in use. Its irritative potential has led to the new galenics, i.e. incorporation in microsponges and in propolyomers, which increased the tolerability significantly. The isomer of tretinoin, isotretinoin, has the same clinical efficacy, but also a lower irritancy. A real breakthrough was adapalene, a retinoid-like agent, with a different retinoid receptor-binding profile, but in addition to the same clinical efficacy on inflammatory and non-inflammatory acne lesions compared to tretinoin, a better tolerability and, therefore, compliance. Unfortunately, over the past years topical retinoids have been less used in inflammatory acne than they should be, taking the the mechanisms of action into account. Topical antimicrobials, in particular topical antibiotics, should be used less often than in the past and only for short periods to avoid the development of resistances. It seems better to combine those agents with topical retinoids, with BPO or with azelaic acid to enhance the efficacy and slow down the development of resistance. BPO is still the gold standard for papular-pustular acne of mild-to-moderate type in concentrations of 2-5%. Azelaic acid is an alternative with efficacy on the comedo and is antibacterial without development of resistances. Finally, the physical removal by electrocautery or CO(2) laser of multiple densely packed closed comedones, macrocomedones and microcysts is necessary to enhance the efficacy of topical comedolytic agents and to speed up the therapeutic results. Photodynamic therapy has not yet been proven efficacious in controlled studies. Blue and red light can probably be used in association with local agents but enhancement of the irritative potential of topical and systemic agents has to be considered.