Abstract
(1) Background: Dissolving microneedles (DMNs), a transdermal drug delivery system, have been developed to treat various diseases in a minimally invasive, painless manner. However, the currently available DMNs are based on burst release systems due to their hydrophilic backbone polymer. Although hydrophobic biodegradable polymers have been employed on DMNs for sustained release, dissolution in an organic solvent is required for fabrication of such DMNs. (2) Method: To overcome the aforementioned limitation, novel separable polycaprolactone (PCL) DMNs (SPCL-DMNs) were developed to implant a PCL-encapsulated drug into the skin. PCL is highly hydrophobic, degrades over a long time, and has a low melting point. Under thermal melting, PCL encapsulated capsaicin and could be fabricated into a DMN without the risk of toxicity from an organic solvent. (3) Results: Optimized SPCL-DMNs, containing PCL (height 498.3 ± 5.8 µm) encapsulating 86.66 ± 1.13 µg capsaicin with a 10% (w/v) polyvinyl alcohol and 20% (w/v) polyvinylpyrrolidone mixture as a base polymer, were generated. Assessment of the drug release profile revealed that this system could sustainably release capsaicin for 15 days from PCL being implanted in porcine skin. (4) Conclusion: The implantable SPCL-DMN developed here has the potential for future development of toxicity-free, sustained release DMNs.
Highlights
Dissolving microneedles (DMNs) are micro-sized polymeric needles that encapsulate drugs and are used for direct release of drugs into the skin with minimal skin irritation following dissolution of the polymeric needles after insertion [1]
Dissolving Microneedles Generated via the Thermal Melting Method for the Sustained Release of Capsaicin
Physical separation of the SPCL-DMNs was achieved by introducing a hydrophilic base polymer, which had the dual function of facilitating complete insertion and separation of the PCL fraction after skin insertion
Summary
Dissolving microneedles (DMNs) are micro-sized polymeric needles that encapsulate drugs and are used for direct release of drugs into the skin with minimal skin irritation following dissolution of the polymeric needles after insertion [1]. DMN technologies have been developed to deliver various drugs such as insulin, vaccines, and minoxidil, most DMN systems focus on overcoming the stratum corneum, the outermost skin barrier, using numerous biodegradable polymers such as hyaluronic acid (HA), carboxymethyl cellulose (CMC), and polyvinylpyrrolidone (PVP) [4]. These polymers are suitable for burst release drug delivery as the drugs are released during the first hour of polymer degradation [5,6,7]. Chronic diseases such as hypertension, chronic inflammation, or alopecia areata require a sustained drug release system on DMNs to minimize the inconvenience associated with regular, long-term drug use [8].
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