Abstract:
The effect of polyethylene glycol-8/SMDI copolymer (PP-15) in controlling the delivery of salicylic acid (SA) and lactic acid (LA) from topical prepns. was studied. The effect of PP-15 on permeation was measured in vitro using flow-through diffusion cells and dermatomed pig skin. Skin uptake was also evaluated over time using tape-stripping and tissue anal. The polymer decreased the flux of SA through pig skin but did not affect the delivery of LA. The polymer increased the overall deposition of SA in the SC but did not change the levels of SA in the viable skin significantly. Skin uptake of LA was not affected by the presence of the polymer. Based on dialysis and cloud point measurements it was found that PP-15 reduced the activity of SA in the vehicle via binding, leading to a decrease in permeation. The binding mechanism accounts for the effect (or lack of effect) of PP-15 on the solutes investigated.