8.3.1.4　Blood supply

The blood supply of the skin does not directly affect the transdermal capacity of drugs，but the more abundant the blood supply is，the more efficient the drugs are transported to the circulatory system after passing through the skin.When the skin is congested，the blood flow speed increases，giving rise to a faster transport of the drug through the epidermis to the dermis.At the same time，the concentration difference between the superficial layer and the deep layer increases，so the drug is more likely to penetrate downward.(https://www.daowen.com)