Substrate for CYP 3A4. Strong clinical inhibitor of CYP 3A4 and 1A. Probably insignificant systemic exposure.

Tacrolimus salve 0.1-0.03 % used in atopic dermatitis. Minimal percutaneous absorbtion, blood concentrations in dermal use <1 ng/mL. Metabolized in the liver by CYP 3A4. One report of uneventful systemic use in one patient with AIP. See: Turton-Weeks et al. Prog Transplant 2001 Sept;11(3):214-216)

Uneventful use reported in 2 patients with acute porphyria.