Why transdermal delivery of drugs like aspirin is so challenging?
Transdermal delivery offers an alternative route that bypasses the gut and may be more convenient and safer for aspirin delivery especially during long-term use. The physiochemical properties of the drug preparation that are factors in the effectiveness of transcutaneous transport are drug stability or volatility, use of a solvent carrier or vehicle, use of a penetration enhancer, and type of delivery device. Because a drug should remain on the skin without evaporating or becoming otherwise inactive, it is suspended in a vehicle—any gel, lotion, or paste used to apply the drug to the skin. Penetration enhancers include several compounds that are mixed into vehicles to alter the molecular environment of the epidermis and facilitate absorption. The delivery system itself occasionally proves to be the ultimate determinant of transdermal drug flow. Disadvantages —The disadvantages of transcutaneous drug delivery include the potential for localized irritant and allergic cutaneous reactions,
