Introduction: Clays provide a powerful drug delivery system due to their specific structure, which can interact with drugs and control their release. Transdermal delivery avoids the transformation of a drug in the liver by dispensing the drug through the skin, avoiding the gastrointestinal tract. Due to ion exchange and the multilayer structure of clay sheets, drugs are entrapped between the sheets, showing this material's high drug release capacity. Recent studies have shown that the addition of 5 wt% clay is suitable for transdermal delivery applications.
Areas covered: In this review, we discussed clay-based polymer microneedles, mechanisms of clay-drug interactions, and antimicrobial effects of clays. We also investigated carriers for clay transdermal drug delivery and in vitro drug release from clay-drug composites. In addition, the most important clays, montmorillonite, halloysite, and sepiolite, were compared and discussed.
Expert opinion: The manufactured product represents an interesting method of sustained drug release through the skin. The duration of drug release can be tuned by modifying the polymer concentration and an appropriate molecular weight in the polymer system. When using clay as a non-polymer transdermal drug carrier, this adjustment is possible by changing the type and concentration of clay.
Keywords: Clay; halloysite; microneedle; montmorillonite; sepiolite.