1999 Volume 59 Issue 2 Pages 96-102
To demonstrate the usefulness of an in vitro drug release test from ointments as a simple screening method, the correlation between the in vitro drug release and the percutaneous absorption of the drug on rats and vasoconstrictor response in human volunteers was investigated. The in vitro drug release test was performed by using a Franz-type diffusion cell, and the amount of drug released at 60 min (Q60) was employed for an index of the in vitro drug release test. The amount of drug in the rat skin at 24 h after application was employed for an index of in vivo percutaneous absorption test. Good correlation was observed between Q60 and the amount of drug in the skin. Furthermore, the correlation between the in vitro drug release test and the vasoconstrictor response was also investigated. Good correlation was observed between Q60 and the vasoconstrictor score. The results demonstrated the usefulness of an in vitro drug release test in predicting the efficacy of ointments. Moreover, good correlation was observed between drug concentration in the bleeding liquid and Q60, or drug in the skin. Therefore, it is most likely that drug concentration in the bleeding liquid is an important parameter of percutaneous absorption.
