Isotretinoin is most effective for patients with acne who fail to respond to other forms of treatment; virtually all patients respond to isotretinoin, 0.5 to 1.0 mg/kg/day. As many as 61% of patients are cured after one course, but 39% require further isotretinoin (16%) or oral antibiotics (23%). The relapse rate can be reduced by the administration of the higher dose of 1 mg/kg/day (thus achieving a significant cumulative dose of > 120 mg/kg), especially to young patients and men with truncal acne and more severe disease. About 85% require a 4-month course, but 15% require longer treatment, with some up to 10 months. There are several reasons for a slow response to treatment, including the presence of macrocomedones, ovarian dysfunction, and as-yet unknown factors. Macrocomedones can be treated with light cautery, ovarian dysfunction with hormonal therapies, and in those persons who have no obvious explanation for slow response, persistence with isotretinoin alone is required. Repeat courses of isotretinoin can also be given. Six years ago most patients treated with isotretinoin had severe acne (60%), but today most patients (60%) have therapy-resistant moderate acne. Isotretinoin is a consideration in such patients to reduce the physical and psychological effects of acne, particularly because there is no simple method to treat acne scars.
Layton AM, Cunliffe WJ