Experimental and mathematical study of the transdermal delivery of sumatriptan succinate from...

A mechanistic model was developed and tested to predict the release of sumatriptan succinate from dissolving microneedles and its permeation across the epidermal skin layers. Material balance equations were written to describe molecular transport followed by absorption into the systemic circulation. The solid drug particles were encapsulated in pyramid-shaped, polyvinylpyrrolidone-based water-soluble microneedles. Plots, generated from literature values and designed to simulate concentration distributions in the epidermal layers, agreed with optical coherence tomography (OCT)images captured at early stages of the experiments. Simulations showed that an increase in the pitch width led to a faster release of the medication. By modifying the governing equations to include a microneedle baseplate, the model was able to estimate short- and long-term release behaviors from in vitro Franz cellexperiments. These studies were performed using three distinct dissolving microneedle formulations and minipig skin as the biological membrane. The calculated diffusion coefficients were one order of magnitude greater than the value estimated when the drug was directly applied to the skin surface. The dissolution rate constant was affected by the concentration of the polymer matrix.