Penetration and Local Effect of Vitamin A on the Skin of the Guinea Pig

Vitamin A penetrates guinea pig skin quickly when dissolved in alcohol or chloroform, primarily through sebaceous glands, but more slowly when dissolved in linoleic or oleic acid, or petrolatum paste. Both vitamin A in oleic or linoleic acid and the fatty acids alone cause epidermal hypertrophy, while fatty acids, with or without vitamin A, slightly retard keratinization. However, vitamin A in alcohol does not affect keratinization. Importantly, hair growth remains unaffected even with large doses of vitamin A in alcohol.