EFFECT OF PRESSURE ON IN-VITRO PERCUTANEOUS-ABSORPTION OF CAFFEINE

The effect of increased pressure, which is a mechanical property of ma ssage, was investigated on the percutaneous absorption of an amphiphil ic compound (caffeine) in vitro on Franz diffusion cells, using excise d human skin. 50 mul of either a 320 mug/ml or a 15 mg/ml acetone solu tion of caffeine were pipetted onto the surface of each skin sample, w hich represented caffeine skin deposits of 5 mug/cm2 and 240 mug/cm2 r espectively. During each experiment, a pressure device delivering 0.25 bar over the atmospheric pressure was applied for the first 30 min on half of the cells. At 2, 4, 6, 8, 12 and 24 h the aqueous dermal bath ing solution, containing 14 g/l albumin, was removed and chromatograph ed. With the applied dose of 5 mug/cm2 no statistical difference was f ound between the cumulated absorbed amount under atmospheric pressure and increased pressure. On the other hand, with the applied dose of 24 0 mug/cm2, the permeation of caffeine was 1.8 times higher under incre ased pressure than the permeation under amtospheric pressure (p < 0.05 ). This enhancing effect of increased pressure was probably connected to either an improved transappendageal route during the percutaneous a bsorption process or a higher stratum corneum filling-up.