Skin Delivery of Natural Compounds by Enhancement Technologies

Abstract

Transdermal delivery represents an attractive alternative to oral delivery of drugs because it can avoid first-pass elimination and gastrointestinal irritation. In addition, transdermal systems are non-invasive and allows self-administration and easy termination which improve patient compliance. As the largest organ of the body, skin plays a very important role in protecting the underlying tissues and internal organs from external stimuli. Stratum corneum is the topmost layer of skin and it forms the rate-limiting barrier to the penetration of most molecules through skin. Only a limited number of drugs, moderately lipophilic with the molecular weight less than 500 Da, are able to be delivered through skin passively, which raises the need for using physical and chemical enhancement technologies to improve the permeation of the drug molecules through skin. Natural products have been a big source of medicinal products for thousands of years with many useful drugs developed from plant sources to treat different diseases. However, the use and development of many promising natural compounds has been limited by poor oral bioavailability, and hence transdermal delivery can be explored as potential route to circumvent the problem.

The present studies mainly focused on using enhancement technologies to improve the skin delivery of natural compounds. For many natural compounds, passive permeation through skin is very low due to their low water solubility and stability. The present study provides a comprehensive investigation of in vitro skin delivery of honokiol, curcumin, and myrsinoside B with different delivery system and using physical or chemical enhancement technologies, such as microneedles or chemical enhancers. Our study also focused on the evaluation of the deactivation efficiency of an activated carbon based drug disposal system with model opioid drugs. Although opioid therapy is successful in relieving pain, it is associated with risks for misuse and abuse. Desorption studies were also done to test the system for potential leaching of the opioids from the disposal system in presence of water and alcohol.