Percutaneous Absorption of Dexamethasone Acetate and Palmitate, and the Plasma Concentration

Abstract

To investigate quantitatively the percutaneous absorption of dexamethasone acetate (DA) and palmitate (DP), gel and petrolatum ointments were prepared and applied to rat skin. DA in the presence of absorption enhancers (Azone® and sorbitan monooleate) was rapidly absorbed, in the form of dexamethasone, through the skin, whereas the absorption after application of DA ointment without enhancers was relatively poor. DP was also efficiently absorbed in the presence and absence of enhancers, with bioavailability of 5.3 and 4.1%, respectively. The absorbed DP was slowly hydrolyzed in the systemic circulation. The percutaneous absorption of drugs from the petrolatum ointments with enhancers was slower than that from the gel ointments. The in vitro release rates of DA and DP from the gel ointments with enhancers were 7.3 and 6.1 mg/h^1/2, respectively and were much higher than those from the petrolatum ointments. The partition coefficient of DP was much larger than that of DA. Thus, it is suggested that DA and DP gel ointments with enhancers are effective in terms of high absorption into the circulation.