An Alternative Hard Capsule Prepared with the High Molecular Weight Pullulan and Gellan: Processing, Characterization, and In Vitro Drug Release

Abstract

Albeit gelatin hard capsules were predominantly applied, their disadvantages call for endeavours on non-gelatin capsules in healthcare aspects. Herein, high molecular weight (Mw = 1 × 10⁶) pullulan was purified from yeast fermentation broth. This high Mw pullulan and commercial low Mw pullulan were respectively co-blended with gellan to prepare the optimal solutions for capsule production. Further investigations, including loss-on-drying, brittleness and tightness, showed that the obtained pullulan-gellan capsules were of low water content, brittleness, leakage, and of high tightness. These capsules exhibited an extended release of amoxicillin over 60 min in simulated gastric fluid. Although the use of high and low Mw pullulan produced composite capsules with similar properties, the required concentration of high Mw pullulan was nearly half of that for low Mw pullulan, suggesting a cost-saving characteristic of using high Mw pullulan. This work proposes a potential substitution of gelatin with pullulan-gellan composites for preparing hard capsules.

Keywords: Gastric extended release; Gellan; Hard capsules; High molecular weight pullulan.