Polymeric Materials as Platforms for Topical Drug Delivery: a Review

With the emergence of novel and more effective drug therapies, increased importance is being placed upon the drug delivery technology. Topical formulations are attractive alternatives to oral formulations and offer several advantages, such as avoiding first-pass hepatic metabolism and gastric degradation. The major obstacle to drug delivery across the skin (transdermal) is the barrier nature of the skin which limits permeation of molecules. A wide range of polymeric materials is currently available for enhancing drug delivery to and across the skin. The synthetic polymers such as polyesters, polyamides, polyurethanes, poly anhydrides, and poly(orthoesters) display advantages of reproducibility of synthesis, a range of material properties, and biodegradability, while the natural polymers including polysaccharides, proteins, and lipids have been widely exploited because of the range of materials and properties available, particularly biocompatibility. This review summarises the important features of the widely different polymers which have guided their selection and application as drug carriers in topical drug delivery.