TRANSDERMAL CONTROLLED DELIVERY OF VERAPAMIL - CHARACTERIZATION OF INVITRO SKIN PERMEATION

The objective of this investigation was to determine the feasibility of transdermal delivery of verapamil by studying its in vitro skin permeation characteristics. Skin permeation experiments were carried out using excised skin from hairless mice mounted in an in vitro permeation system. The effects of age, sex and site of skin excised, as well as the influence of pH and of drug concentration in the donor solution on the permeation rate of verapamil were studied. Successive stripping of the stratum corneum was observed to increase the permeation rate until the stratum corneum was completely removed, suggesting that stratum corneum plays a rate-limiting role in the skin permeation of verapamil. The physico-chemical properties of verapamil, viz., diffusivity, partition coefficient and solubility, in stratum corneum and viable skin were determined based on the bilayer skin model.