Soft beta-adrenergic agonists for the topical treatment of psoriasis

The soft-drug 1 (R = Me, Et) and pro-soft-drug 3 have been prepared as models of topical anti-psoriatic beta-adrenergic agonists. The chemical hydrolysis of 3 proceeded via the acid 18 with a maximum stability at apparent pH similar to 4.0. In the presence of PLCE, the required metabolism of 3 to the soft-drug 1 (R = Et) was achieved, which slowly degraded to the dihydroxy acid 2. Soft-drug 1 (R = Et) was poorly transported across a silicone membrane, whereas the pro-soft-drug 3 was more efficient and the rate increased over the donor apparent pH range 3-8. Soft-drug 1 (R = Et) was a full beta-agonist on the guinea-pig tracheal preparation, whereas the pro-soft-drug 3 produced only slowly developing responses at high concentrations (>10 mu M).