The use of second-order derivative UV spectroscopy to monitor the percutaneous absorption of naphazoline and oxprenolol

Abstract

Derivative spectroscopy was used to measure the transfer of the cationic drugs, oxprenolol and naphazoline, across full-thickness human skin in vitro. Flow-through diffusion cells were employed. These allowed the receptor fluid to be pumped through a microprocessor-controlled UV spectrophotometer. Spectra were then recorded at preprogrammed intervals. From the second-order derivative curves it was possible to evaluate the concentration of each diffusant within the receptor phase. Confirmation of the technique was established using HPLC. The steady-state fluxes of both drugs were measured. The diffusion of naphazoline and to a lesser extent oxprenolol were enhanced in the presence of lauric acid. The use of derivative spectroscopy in this manner provides a rapid, labour-saving technique for the continuous monitoring of the absorption of various drugs across excised skin.