An evaluation of the pharmaceutical properties of the Nigerian baobab polysaccharide for sustained release oral tablets

Abstract

Natural polysaccharides have various applications, and their use is on the rise due to properties including biodegradability, biocompatibility, cytocompatibility and not eliciting negative immune responses. Natural polysaccharides have also been reported to be efficient biopolymers that can be used in oral dosage forms. To this end, this study investigated the potential of using the Nigerian baobab polysaccharide as a renewable pharmaceutical excipient and its impact on the release of theophylline as a model drug. The results indicate that the extraction process yielded an amorphous polysaccharide from the baobab oblong fruit. The thermogravimetric analysis showed weight loss to occur in three phases typical for polysaccharide decomposition. Differential scanning calorimetry (DSC) revealed the polysaccharide was stable until around 175 °C, after which thermal degradation takes place. Tablet formulations containing different concentrations of baobab were evaluated for mechanical properties, flowability, and dissolution characteristics. An increase in baobab content improved the mechanical strength of the tablets. The increase in the baobab concentration simultaneously brings about a decrease in the porosity of the compacts from 11% to 9%, demonstrating its suitability for use as tablet formulations. In-vitro dissolution studies in acidic media (pH 1.2) showed that formulations with higher baobab content (30% – 57.5%) demonstrated sustained release characteristics, with no burst release observed. In pH 6.8 however, an increase in the polysaccharides content seemed to contribute towards “burst release”. These distinctive behaviours at different pHs suggest significant potential with regards to exploiting and understanding the functional properties of the polysaccharide to aid a formulator to manipulate drug release.