Topical Delivery of Retinyl Ascorbate

The study investigated the effects of skin stretching and hair follicle sealing on the delivery of retinyl ascorbate (RA-AsA) to the epidermis using porcine ear skin in vitro. The skin was stretched by 2 mm and 4 mm, and hair follicles were sealed in some sections. Results showed no significant difference in RA-AsA delivery between unstretched skin and skin with sealed follicles. However, stretching the skin by 2 mm and 4 mm significantly increased RA-AsA delivery, with a p-value of less than 0.001 for the 4 mm stretch. The study concluded that while the follicular route does not contribute to dermal absorption in native skin, stretching can enhance drug delivery by 20-40%. Skin stretching beyond 7% was noted to be challenging.