*3.8. Drug Retention Analysis*

The drug retention study (see Figure 5), revealed that the retention of methotrexate is more in the deep layers of the skin. In the case of F5, when compared to other formulations, there is a statistically significant difference in drug retention primarily in the epidermis and dermis (ANOVA, *p* < 0.05).

**Figure 5.** Skin drug retention analysis of methotrexate patches (F1–F9), Data were expressed as mean ± SD, *n* = 3. Significant compared to formalin (*p* < 0.05).
