Acne, cystic etretinate

Isotretinoin, or 13-cis-retinoic acid, and etretinate are available for oral administration. Isotretinoin is a synthetic retinoid that is used for sever cystic acne, recalcitrant to standard therapies. Its mechanism of action is not well understood but involves the inhibition of sebaceous gland size and function. 

Retinoids in Dermatology 13-Qs-retinoic acid (isotretinoin, Accutane ) is used orally, and all-trans-retinoic acid (Tretinoin ) topically, for treatment of severely disfiguring cystic acne. Etretinate (the trimethoxyphenyl analog of retinoic acid) and tazarotene (a receptor-specific retinoid) are used topically for the treatment of psoriasis. They are effective in cases in which other therapy has failed, and at lower levels than are required for the control of tumor development in experimental animals, although they have heen associated with hirth defects (Section 2.5.1.1 fohnson and Chandrarama, 1999). 

More than 1500 retinoids have been synthesized. Two in particular, 13-cw-retinoic acid (isotretinoin) and etretinate (Figure 38-4), have generated considerable interest as agents for the treatment of dermatological disorders. 13-cA retinoic acid inhibits sebum production, is the drug of choice for treatment of severe cystic acne, and is useful in the treatment of other forms of acne. Etretinate is used in Europe for treatment of psoriasis and related disorders. 

Interest in the toxicity of the retinoids has resulted from their increased use in the treatment of dermatological disorders (Peck, 1980 Pardini, 1981 Elias and Williams, 1981 Windhorst, 1982 Chapter 16, this volume) and neoplasms (Spom, 1977 Spom and Newton, 1981 Spom, 1982 Bollag, 1979 Lotan, 1980 Newbeme and Rogers, 1981 Chapter 14, this volume). Isotretinoin (13-cw-retinoic acid, Ro 4-3780, Accutane) has become available in the United States for use in the treatment of severe recalcitrant cystic acne in Europe, etretinate (Ro 10-9359, Tegison) is used for treatment of psoriasis. The toxicity of these retinoids has been exhaustively studied in laboratory animals as part of the regulatory approval process. 

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