A thermo-responsive hydrogel loaded with an ionic liquid microemulsion for transdermal delivery of methotrexate

Systemic administration of methotrexate (MTX), the gold standard for the treatment of psoriasis, can cause adverse side effects. To address this issue, a thermally responsive hydrogel loaded with an ionic liquid microemulsion (IL-ME) was developed for the transdermal delivery of MTX. The microemulsion was prepared using water, Tween 20 and choline and geranic acid (CAGE) ionic liquid. The solubility of methotrexate in the IL-ME was 9-fold higher than that in phosphate buffer (PBS). The hydrogel (Gel) based on isopropylacrylamide and silk fibroin acts as a drug reservoir to achieve temperature-responsive drug release in the human epidermis. The loading of the IL-ME or MTX-containing IL-ME on the Gel produced a ME@Gel or MTX/ME@Gel. In vitro permeation experiments showed that the MTX/ME@Gel exhibited a 27.6% increase in MTX permeation. In addition, IL-ME exhibits strong antibacterial activity. In vivo studies indicated that when compared with the results obtained in PBS medium, the MTX/ME@Gel could effectively treat skin redness, swelling and scaling caused by imiquimod (IMQ). In general, the present study demonstrated that the MTX/ME@Gel provides vast potential to serve as a biocompatible drug carrier for the efficient delivery of poorly soluble drugs, i.e., MTX in this particular case.