Increased permeability of psoriatic skin to the protein, plasminogen activator inhibitor 2.

The penetration and permeation of the recombinant protein plasminogen activator inhibitor type 2 (PAI-2) in two formulations, one containing a penetration enhancer, into the psoriatic and uninvolved skin of eight patients with plaque-type psoriasis were investigated. Penetration and permeation of PAI-2 were measured by gamma counting and imaging following radiolabelling of a fraction of the applied PAI-2 with (123)I. The feasibility of topical delivery of drug to psoriatic plaques was confirmed by the finding that the permeability of psoriatic plaques to radiolabelled PAI-2 (P=0.007) and free (123)I (P=0.001) was approximately tenfold higher than the permeability of uninvolved skin. The addition of a penetration enhancer improved the permeation of PAI-2 into psoriatic plaques from an average of 35% to 46% (P=0.005). Occlusion decreased the permeation amount of PAI-2 from 46% to 15% due to losses on the occlusive dressing (P=0.001).