Background Isotretinoin is a synthetic retinoid, derived from vitamin A, with multiple mechanisms of action and highly effective in the treatment of acne, despite common adverse events, manageable and dose-dependent. Dose-independent teratogenicity is the most serious. Therefore, off-label prescriptions require strict criteria. Objective To communicate the experience and recommendation of Brazilian dermatologists on oral use of the drug in dermatology. Methods Eight experts from five universities were appointed by the Brazilian Society of Dermatology to develop a consensus on indications for this drug. Through the adapted DELPHI methodology, relevant elements were listed and an extensive analysis of the literature was carried out. The consensus was defined with the approval of at least 70% of the experts. Results With 100% approval from the authors, there was no doubt about the efficacy of oral isotretinoin in the treatment of acne, including as an adjunct in the correction of scars. Common and manageable common adverse events are mucocutaneous in nature. Others, such as growth retardation, abnormal healing, depression, and inflammatory bowel disease have been thoroughly investigated, and there is no evidence of a causal association; they are rare, individual, and should not contraindicate the use of the drug. Regarding unapproved indications, it may represent an option in cases of refractory rosacea, severe seborrheic dermatitis, stabilization of field cancerization with advanced photoaging and, although incipient, frontal fibrosing alopecia. For keratinization disorders, acitretin performs better. In the opinion of the authors, indications for purely esthetic purposes or oil control are not recommended, particularly for women of childbearing age. Conclusions Approved and non-approved indications, efficacy and adverse effects of oral isotretinoin in dermatology were presented and critically evaluated.

Background Topical tretinoin cream is the gold standard treatment for skin ageing, particularly photoaging. The purpose of tretinoin peel was to obtain similar results, but in a shorter time, however, there have been few controlled trials on its effectiveness. Objective To compare efficacy and safety of tretinoin 0.05% cream and 5% as a peeling agent on photoaging and field cancerization of the forearms. Methods Clinical trial with therapeutic intervention, prospective, randomized (computer‐generated randomization list), parallel, comparative (intrasubject) and evaluator‐blinded (except for histology and immunohistochemistry), including 24 women (48 forearms) aged over 60 years who have not undergone hormone replacement and categorized as Fitzpatrick skin phototype II or III. The forearms of the participants were randomized for treatment with 0.05% tretinoin cream three nights a week, or 5% tretinoin peel every 2 weeks. The opinion of the participant, severity of photoaging, corneometry, profilometry, high‐frequency ultrasound, histology (haematoxylin–eosin and Verhoeff stainings) and immunohistochemistry (p53, bcl‐2, Ki67 and collagen I) were assessed. Results One participant dropped out. The mean photoaging score reduced 20% and the mean actinic keratosis (AK) count reduced 60% with no difference between treatments. Three efficacy parameters showed opposite effects between the tretinoin treatments (P < 0.05%): (i) thickness of the corneal layer decreased with 0.05% tretinoin and increased by 5%; (ii) dermis echogenicity increased by 0.05% and decreased by 5% and (iii) Ki67 expression increased by 0.05% and decreased by 5%. There was good tolerability for both regimens. Conclusion Tretinoin as a cream 0.05% or peeling (5%) is safe and effective for the treatment of moderate photoaging and forearm field cancerization. The cream was superior in improving ultrasonographic parameters of ageing. Peeling was shown a superior performance in the stabilization of field cancerization.

Our observations may contribute to the discussion of the negative influence of oral isotretinoin on wound healing. Other studies are necessary to reevaluate the current recommendation of a 6- to 12-month waiting period after oral isotretinoin treatment before performing dermabrasion or fractional ablative laser for acne scar revision.

A validated clinical photoaging scale for forearms with internal consistency, reliability, and validity was developed.

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