INFLUENCE OF D-LIMONENE ON THE TRANSDERMAL PENETRATION OF FELODIPINE

Felodipine is a calcium antagonist, one of the dihydropyridines, with potential application in transdermal therapeutic systems (TTS). Earlie r studies reported that the high lag time of this drug limited its pot ential development in a TTS. The present study analyzes the effect of d-limonene at concentrations of 0.5, 1, 5 and 10% on the transdermal p enetration of this drug. The study was performed using a diffusion tec hnique in vitro, with the skin of the hairless rat. d-limonene signifi cantly reduced the lag time (T-1) to 1.4 h at a concentration of 1% (c ompared with 9.8 h in its absence). Higher concentrations did not prod uce a significant decrease in the value of this parameter. The presenc e of d-limonene in the formulae produces an increase in the permeabili ty. constant (K-p) and the flux (J). The relation between this increas e and the percentage of d-limonene was non-linear. An asymptotic value was obtained at a concentration of 5%, with increases of 993% and 157 0% for K-p and J, respectively.