Enhanced skin permeation of a lipophilic drug using supersaturated formulations

Supersaturation was used to enhance the permeation of a lipophilic model co mpound (a lavendustin derivative, LAP) through excised pig skin in vitro. T he drug was dissolved in a series of liquid and semisolid vehicles (in whic h it had different solubilities) and which were prepared using either (i) t he method of mixed cosolvents, (ii) the method of solvent evaporation, or ( iii) the method of dissolving the drug with heating. Saturated formulations showed comparable permeation rates through the skin, independent of the ab solute concentration of the drug in the vehicle. Supersaturated solutions a t a degree of saturation of two resulted in a doubling of the drug permeati on rate. These experiments show, therefore, that the percutaneous absorptio n of LAP may be consistently increased using supersaturated formulations, i ndependent of the type and composition of the vehicles and independent of t heir method of preparation. (C) 2001 Elsevier Science B.V. All rights reser ved.