Designing a unique feedback mechanism for hydrogel-forming microneedle array patches: a concept study

Although microneedle array patch (MAP) technology is reaching ever closer to regulatory approval, it remains imperative that approaches to further improve patient acceptance are still explored. Addressing this perception, a water-filled reservoir was incorporated into a hydrogel-forming MAP system to provide a novel feedback mechanism. To confirm successful MAP skin insertion, the end user would both hear and feel the rupture of the water-filled reservoir.

Interestingly, a 50-µL water-filled reservoir ruptured at 30.27 ± 0.39 N, which has previously been shown as the mean application force for MN insertion in human subjects following appropriate instruction. Importantly, no significant difference in % cumulative permeation of FITC-dextran 10 kDa and fluorescein sodium after 24 h was observed between a 50-µL reservoir and the current method of application that has been successfully used in both in vitro and in vivo studies (p > 0.05).

Therefore, as drug delivery was not affected, this proof-of-concept study has shown that a water-filled reservoir feedback mechanism has the potential to serve as a viable tool for consistent MAP skin insertion.

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Materials: Elastollan® thermoplastic polyurethane pellets with 95A shore hardness (TPU 95A) was generously supplied by DistruPol Ltd, Dublin, Ireland. Fluorescein isothiocyanate–dextran (FITC-dextran 10, MW = 8000–12,000 Da) was purchased from TdB Consultancy AB (Uppsala, Sweden). Fluorescein sodium (MW = 376 Da) and poly(ethylene glycol) (PEG) with MW = 10 000 Da were purchased from Sigma-Aldrich, Dorset, UK. Gantrez® S-97, a co-polymer of methyl vinyl ether and maleic acid (PMVE/MA) was a gift from Ashland, Kidderminster, UK. Sodium carbonate (Na₂CO₃) was purchased from BDH Laboratory Supplies, London, UK. Pearlitol® 50C-Mannitol was supplied by Roquette, Lestrem, France. Cryogel SG3 was provided by PB Gelatins, Pontypridd, UK.

Article information: Hutton, A.R.J., Kirkby, M., Larrañeta, E. et al. Designing a unique feedback mechanism for hydrogel-forming microneedle array patches: a concept study. Drug Deliv. and Transl. Res. (2021). https://doi.org/10.1007/s13346-021-01033-1