TOPICAL FK506 - CLINICAL POTENTIAL OR LABORATORY CURIOSITY

Cyclosporine A (CsA) is an immunosuppressant that is efficacious in se veral inflammatory skin disorders. Its use is, however, limited due to systemic side-effects. Topical forms of CsA have been tried but they do not seem to be effective presumably due to insufficient penetration to skin. Tacrolimus (FK506) is another immunosuppressant that has alm ost similar effects on the cellular level as CsA. FK506 is 10-100 time s more potent than CsA and it has lower molecular weight. Recent studi es suggest that topical FK506 penetrates human skin in amounts exceedi ng those of topical CsA. Topical FK506 also seems to suppress skin inf lammation in man. These findings prompt for further clinical studies o f efficacy and safety of topical FK506.