Kinetic Modelling and In Vitro Release Mechanism of Levodopa from Sporopollenin-Based Microcapsules in Human Blood Plasma

Abstract

Levodopa (LD) remains the most effective therapy for Parkinson's disease, but its short plasma half-life necessitates frequent dosing and contributes to motor complications.This study evaluated the in vitro release profile of LD from sporopollenin microcapsules in human blood plasma and applied kinetic modelling to elucidate the release mechanism. LDloaded sporopollenin microcapsules (0.5 g) were prepared by vacuum-assisted, pH-triggered precipitation and suspended in human plasma at 37 °C with moderate agitation (50 RPM).LD release was quantified over twelve hours using UV-Vis spectrophotometry, with withdrawn aliquots replaced with fresh plasma to maintain a constant assay volume. The data were fitted to Zero-order, First-order, Higuchi, and Korsmeyer-Peppas models. An initial burst release occurred within 30 min, rapidly elevating LD concentration, followed by sustained release up to 12 hours, markedly extending drug availability beyond LD's normal half-life. Kinetic modelling showed that the Korsmeyer-Peppas model provided the best fit (R² = 0.928), with an n-value of 0.0369, consistent with Fickian diffusion through the sporopollenin matrix. Sporopollenin microcapsules thus achieved both rapid onset and sustained release of LD in human plasma, confirming their potential as a natural, biocompatible carrier to improve Parkinson's disease management. To our knowledge, this is the first report of LD release kinetics from sporopollenin in human plasma.Instruments, UK), a pH meter (HANNA Instruments), a thermocouple, a vacuum pump, a Buchner filter, and a water bath.