The percutaneous delivery of prostaglandin E1 and its alkyl esters by microemulsions

Two microemulsion systems were developed for percutaneous delivery of PGE1 and its alkyl esters through hairless mouse skin. Microemulsion I was based on Labrasol (HLB 14) as a nonionic surfactant and Plurol oleique (HLB 10) as a cosurfactant, whereas microemulsion II employed Labrafac CM 10 (HLB 10) as a nonionic surfactant and Lauroglycol (HLB 4) as a cosurfactant. The addition of a variety of cosolvents into both microemulsion systems was found to cause insignificant effects on the formation of the microemulsions. The effect of a variety of cosolvents on the percutaneous penetration of PGE1 and its alkyl esters through hairless mouse skin was further examined. The penetration of all the prostaglandins examined from microemulsion II was insignificant compared to microemulsion I. The penetration rate of PGE1 was higher than its alkyl esters from microemulsion I with the same cosolvent. The enhancement of PGE1 percutaneous penetration from microemulsion I was positively correlated with the hydroxyl number of polyhydric alcohols. For a given number of hydroxyl groups, an alcohol with an optimal carbon number enhanced the penetration rate to the greatest degree. However, the penetration rate of PGE1 from all formulations appeared inadequate for practical use.