Fabrication and characterisation of self-applicating heparin sodium microneedle patches

The aim of this study was to develop heparin sodium loaded microneedle patches using different compositions of polyvinyl alcohol polymer and sorbitol. A vacuum micromolding technique was used to fabricate microneedle patches while heparin sodium was loaded into needle tips. Physical features of patches were evaluated by measuring thickness, width, folding endurance and swelling percentage. Patches were also characterised by optical microscopy and scanning electron microscopy to determine the microneedle length and surface morphologies. A preliminary assessment of the microneedle performance was studied by examining the in-vitro insertion to the parafilm and recording the in-vitro drug release profile. In-vivo activity of patches was confirmed by measuring activated partial thromboplastin time and histological examination of the micropierced skin tissues. Prepared patches were clear, smooth; uniform in appearance; with sharp pointed microprojections and remained intact after 1000 folding. The microneedles were stiffer in nature, as they reproduce microcavities in the parafilm membrane following hand pushing without any structural loss. Insertion study results showed successful insertion of microneedles into the parafilm. Disrupted stratum corneum evident from histological examination confirmed successful insertion of the microneedle without affecting the vasculature. In-vitro release study confirmed ∼92% release of the loaded drug within 120 min. A significant prolongation of activated partial thromboplastin time (4 folds as compared to negative control) was recorded following the application of heparin sodium loaded microneedle patch onto rabbit skin. In conclusion microneedles are a valuable drug delivery system, benefiting the patients with minimal skin invasion and also allowing self-administration of heparin sodium in a sustained release manner for the management of chronic ailments.