Optimisation of Backing Layer Formulations via Rational Polymer Selection to Improve the Insertion of Dissolving...

Area of Science:

• Biomaterials Science
• Drug Delivery Systems
• Dermatology

Background:

• Dissolving microneedles (MNs) are a promising platform for transdermal delivery of complex molecules.
• MNs are typically fabricated using a two-step casting process, allowing for adaptable polymer selection in needle and backing layers.
• The influence of the backing layer on MN insertion and drug delivery remains less understood compared to the needle layer.

Purpose of the Study:

• To investigate the impact of different backing layer polymer formulations on microneedle insertion.
• To elucidate the relationship between backing layer material properties and microneedle performance.
• To assess the effect of backing layer composition on the transdermal delivery of insulin.

Main Methods:

• Microneedle arrays were fabricated with a polyvinylpyrrolidone-co-vinyl acetate needle layer and various backing layers (sodium carboxymethylcellulose, poly(vinyl alcohol), polystyrene).
• Insulin was incorporated into the needle layer as a model protein therapeutic.
• Insertion efficiency and depth were evaluated, followed by in vitro permeation studies to quantify insulin delivery.

Main Results:

• Microneedles with a poly(vinyl alcohol) (PVA) backing layer exhibited enhanced insertion efficiency and depth.
• PVA backing significantly improved insulin delivery, achieving a cumulative recovery of 17.6% of the total loaded dose.
• The choice of backing layer polymer demonstrably influenced both microneedle insertion mechanics and drug permeation.

Conclusions:

• The backing layer formulation is a critical factor in the performance of dissolving microneedle systems.
• Polymer selection for the backing layer directly impacts microneedle insertion characteristics and therapeutic agent delivery.
• Future microneedle development should prioritize rational selection and thorough characterization of backing layer materials based on application-specific requirements.