Topical Tretinoin for Photoaged Skin-Reply

Abstract

In Reply. —In answer to Dr Pazmino, laboratory and drug absorption studies were not done in our study because of the known safety of topical tretinoin. Plasma levels of tretinoin were undetectable after applications of 0.025% tretinoin cream to the arms, legs, and back twice daily for 28 days or 1.0% tretinoin cream once to the entire body. 1 Any minimal absorption of tretinoin through intact skin and any prostaglandins in the skin (which are metabolized locally) would be unlikely to affect the kidney directly. Based on our experience with retinoids 2,3 and on 17 years of safe use of tretinoin without reported vasculitis or effects on kidney function (E. G. Thorne, MD, Ortho Pharmaceutical Company, oral communication, March 1988), we conclude that it is unnecessary to perform kidney function measurements in patients using tretinoin topically. Day-to-day variation and laboratory or collection errors could account for some of the findings