2.8. Ex-vivo skin permeation and deposition study

Horizontal Franz diffusion cell apparatus was utilized to perform ex-vivo permeation experiment. The Franz diffusion cell having 0.78 cm² permeation area and a 5.2 mL receiving compartment was utilized. The system's temperature was kept at 32 °C and recently excised rat skin was put between the donor and receiving compartments. Test formulations were inserted in the donor compartment, which have non-occlusive hydration system. Samples from the receiving compartment were taken at intervals of 0.5, 1, 2, 3, 4, 6, 8, 12 and 24 h while replacing the sample with an equivalent volume of PBS [43]. Finally, the graph was plotted showing the cumulative drug permeation per unit area vs time.

After ex-vivo permeation investigation, the rat skin was dismounted and to get rid of any residual formulation skin sections were rinsed with distilled water and blot dried [44]. The SC was separated from the remaining skin layers utilizing the tape stripping technique. With 15 to 20 layers of adhesive tape, the skin parts were stretched and peeled. Drugs were released from tape strips by crushing the strips in methanol at 37 °C and the spectrophotometer was used to detect them. Following tape removal, the remaining skin part was chopped into small pieces, crushed, and homogenized in methanol. The drugs were then quantified using a UV–visible spectrophotometer [45].