**5. Conclusions**

The results of the current study indicate that methotrexate, having EC/HPMC polymers at different concentrations, has the best and excellent patch-forming abilities. All formulated patches (F1–F9) were evaluated, and the F5 formulation exhibited the best in vitro drug release pattern and ex vivo drug permeation ability, having the highest deposition of methotrexate compared to other formulated patches. This greater retention on the deeper layer of the skin is significant for targeting psoriasis because this chronic ailment prevails in the epidermis and dermis layers. Thus, F5 showed the best potential for transdermal drug delivery. The controlled and slow release of the drug showed that the F5 formulation is suitable for transdermal patches. FTIR studies showed no interaction between the drug (methotrexate) and polymers (EC/HPMC) used. Methotrexate was distributed uniformly in the formulated patches and was of an amorphous nature.

**Author Contributions:** Conceptualization, A.K.A.; Data curation, A.K.A. and A.N.; Formal analysis, A.K.A.; Funding acquisition, M.M.A.-D.; Investigation, M.S.L. and A.K.A.; Methodology, A.K.A. and A.N.; Resources, M.M.A.-D.; Supervision, A.N.; Validation, A.K.A.; Visualization, A.K.A.; Writing original draft, M.S.L.; Writing—review & editing, A.K.A., A.N., S.A.R., M.H.R., S.Y.A.O., S.G.B., L.A. and M.M.A.-D. All authors surely contributed to this work. All authors have read and agreed to the published version of the manuscript.

**Funding:** This project was supported by the Researchers Supporting Project (RSP-2021/35), King Saud University, Riyadh, Saudi Arabia.

**Institutional Review Board Statement:** The study was conducted according to the guidelines of the Declaration of Helsinki and approved by the Institutional Review Board/Ethics Committee of GOMAL UNIVERSITY (protocol code No: 116/ERB/GU and 26/02/2021).

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Acknowledgments:** This project was supported by the Researchers Supporting Project (RSP-2021/35), King Saud University, Riyadh, Saudi Arabia.

**Conflicts of Interest:** The authors declare no conflict of interest.

#### **References**

