Isotretinoin in the treatment of acne: histologic changes, sebum production, and clinical observations.

Isotretinoin was administered orally for 16 weeks, in a dosage of 1 mg/kg/day, to seven men with severe acne. A 36.2% reduction of nodulocystic lesions was observed at the conclusion of treatment and a 47.2% reduction was noted at the end of a 16-week follow-up period. However, there was an 88.4% decrease in sebum production and a marked reduction histologically in sebaceous gland size after 16 weeks of treatment, with a partial recovery of glandular activity at 32 weeks. The failure to observe a more striking overall response clinically resulted primarily from two of the seven patients showing worsening or no improvement of their disease, despite profound sebaceous gland inhibition. These findings suggest that the marked sebostatic effect of isotretinoin may not be the sole explanation for its mechanism of action in reducing the severity of acne.