Microneedles for transdermal drug delivery using clay-based composites

ABSTRACT

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
• microneedle
• montmorillonite
• halloysite
• sepiolite

Article highlights

• Clay provides a powerful drug delivery system due to its biocompatibility and ion exchange properties.

• The use of clay in the microneedle structure can improve drug bioavailability and needle stiffness.

• Montmorillonite, kaolinite, halloysite, and sepiolite are the most frequently used clays for transdermal delivery.

• Clay can be used as a filler for polymer microneedles or as a carrier without a polymer for drug delivery purposes.

• Polycaprolactone, polyglycolic acid, polylactic acid, and their copolymers are known as economical polymer materials that have biocompatibility and excellent strength for transdermal delivery.

• The mechanism of the clay-drug interaction was discussed.

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants, patents received or pending, or royalties.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Additional information

Funding

The authors acknowledge the financial support of the National Research Foundation of Korea (NRF-2021R1I1A1A01042943).