http://www.advancesinhealth.com/acne-treatment/index.html We describe and compare the different topical retinoids, tretinoin (all-trans-retinoic acid), isotretinoin (13-cis-retinoic acid), adapalene (derived from naphthoic acid), and tazarotene (acetylenic retinoid) They act mainly as comedolytics, but anti-inflammatory actions have also been discovered recently.