Development of Norelgestromin Dissolving Bilayer Microarray Patches for Sustained Release of Hormonal Contraceptive

Abstract

Microarray patches (MAPs) offer a noninvasive and patient-friendly drug delivery method, suitable for self-administration, which is especially promising for low- and middle-income country settings. This study focuses on the development of dissolving bilayer MAPs loaded with norelgestromin (NGMN) as a first step towards developing a future potential drug delivery system for sustained hormonal contraception. The fabricated MAPs were designed with the appropriate needle lengths to penetrate the stratum corneum, while remaining minimally stimulating to dermal nociceptors. Ex vivo assessments showed that the MAPs delivered an average of 176 ± 60.9 μg of NGMN per MAP into excised neonatal porcine skin, representing 15.3 ± 5.3% of the loaded drug. In vivo pharmacokinetic analysis in Sprague Dawley rats demonstrated a Tmax of 4 h and a Cmax of 67.4 ± 20.1 ng/mL for the MAP-treated group, compared to a Tmax of 1 h and a Cmax of 700 ± 138 ng/mL for the intramuscular (IM) injection group, with a relative bioavailability of approximately 10% for the MAPs. The MAP-treated rats maintained plasma levels sufficient for therapeutic effects for up to 7 days after a single application. These results indicate the potential of NGMN-loaded dissolving bilayer MAPs, with further development focused on extending the release duration and improving bioavailability for prolonged contraceptive effects.

Keywords: hormonal contraception; intradermal delivery; microarray patch; microneedles; norelgestromin; pregnancy prevention; sustained-release.

Figure 1

Manufacturing steps of bilayer NGMN microneedle arrays.

Figure 2

(A) Digital microscopy image. Representative SEM images of tip-loaded microneedles containing NGMN, showing (B) a fully formed microneedle array and (C) a needle tip matrix.

Figure 3

(a) Assessment of mechanical properties of NGMN MAPs using a texture analyzer, measured by the percentage of height reduction in the MAP shaft under a 32 N compression force against an aluminum block (mean ± standard deviation [SD], n = 3). (b) Evaluation of NGMN microneedle penetration in eight Parafilm M layers as an artificial skin model, indicating the percentage of holes and corresponding insertion depths achieved with a 32 N force (mean ± SD, n = 3).

Figure 4

Pharmacokinetic profile of NGMN in Sprague Dawley rats following administration (2 mg NGMN suspension per rat) by IM injection or by applying four dissolving NGMN MAPs. Data are reported as the means ± SDs (n ≥ 3).