2001 Volume 61 Issue 3 Pages 119-127
Delivery of drugs via the skin has many attractions, including avoidance of gastro-intestinal disturbance and first-path metabolism, long-term maintenance of therapeutic plasma concentration and increased patient acceptability. This paper discusses the factors influencing the percutaneous absorption of drugs: lipophilicity, molecular size, melting point, cutaneous metabolism and skin binding of drugs. Additionally, quantitative structure-permeability relationships (QSPR) for skin penetration were discussed based on the octanol-water partition coefficient, molecular weight and electronic charge of drugs. Nonirritant enhancement methods, such as use of nonirritant penetration enhancers and formation of a complex or an ion pair, for drug penetration through skin were also described. As a result, the suitability of a drug for transdermal drug delivery was proposed.
