Enhanced topical delivery of tacrolimus by a carbomer hydrogel formulation with transcutol P

Tacrolimus (TAC), a non-steroidal anti-inflammatory and immunosuppressive agent, is used for the treatment of atopic dermatitis (AD) and skin immune diseases. TAC-loaded topical hydrogel formulations composed of carbomer, carnosine, transcutol P (diethylene glycol monoethyl ether) and humectant were prepared. For comparison, TAC-loaded topical cream-type formulations were also prepared and commercially available TAC ointment was used as a reference. A drug release study in vitro revealed that the total amount of TAC released from hydrogels over 24?h was approximately 30 times greater than that for the reference formulation. Compared to the reference ointment and creams, carbomer gel formulations showed higher skin permeation and retention of TAC (significantly different at p?