The percutaneous penetration of prostaglandin E-1 and its alkyl esters

The percutaneous delivery of PGE(1) and its alkyl esters in alcoholic salin e solution through hairless mouse skin was compared. The quantification of alkyl esters was based on the same principle as that for PGE(1), which was converted to PGB(1) to enhance the sensitivity and minimize the interferenc e. Results showed that it was PGE(1) that appeared in the receiver compartm ent for all alkyl eaters examined. The flux of all alkyl esters of PGE, in the same concentration was higher than PGE(1) itself at most of saline vehi cle with various fractions of alcohol. The maximal flux for a fixed concent ration of each alkyl ester appeared at different fractions of alcohol. When the fractions of alcohol was kept constant, the alkyl ester that showed th e maximal flux at this concentration appeared to have a longer chain length with increasing the fraction of alcohol. But isopropyl ester deviated from this order. It was concluded that the alkyl ester derivatives promoted the penetration of PGE(1) mainly as a result of enhancing the drug partitionin g into the stratum corneum. The alcohol fraction that needed to achieve the maximal flux at the same concentration increased with the increase of alky l chain length, which resulted in the decrease of solubility parameter. It is necessary to optimize the fraction of alcohol in the saline solution in order to achieve the maximal flux at a fixed concentration for these alkyl esters with different alkyl chain length. (C) 1999 Elsevier Science B.V. Al l rights reserved.