Formulation and evaluation of microspheres using pregelatinized starches from Digitaria exilis (poaceace), Coleus esculentus (Lamiaceace), Colocasia esculenta (Araceace) and Solanium tuberosum (Solanaceace)

Abstract

Microspheres provide a delivery system that offers prolonged/controlled drug delivery with improved bioavailability, stability and ability to target drugs to specific sites at predetermined rate. This study aimed to formulate and evaluate microspheres using pregelatinized starches obtained from Digitaria exilis, Coleus esculentus, Solanium tuberosum and Colocasia eculenta. Physicochemical properties of the pregelatinized starches were evaluated using standard methods. Paracetamol-loaded microspheres were formulated by dissolving sodium alginate (2 g), pregelatinized/native starch (1 g) and paracetamol powder (1 g) in 100 ml distilled water. This was added, dropwise, using 0.8 mm needle & syringe at a rate of 2 ml/minute, into an already prepared calcium-chloride-dihydrate solution (10 % w/v) and placed on magnetic stirrer (250 rpm). It was allowed 15 minutes for curing. The spheres were then collected, washed repeatedly and air - dried for 24 hours. Physicochemical properties of the pregelatinized starches showed better flow and compaction properties compared to the native. Microspheres formulated with pregelatinized starches were smaller and more spherically-shaped compared to those with the native starches; this is essential for binding and release of high concentration of the drug. The swelling power of the formulated microspheres was in the order: F8 > F5 > F4 > F1 > F6 > F7 > F2 > F3. The dissolution profiles indicated gradual and consistent increase in the release of paracetamol from the microspheres, with those prepared using the pregelatinized starches (F5 - F8) showing more gradual release over time compared to those prepared using native starches (F1 - F4). Thus, pregelatinized starches of the four plants can be utilized in the formulation of microspheres for controlled-release medications, as an alternative to synthetic polymers in drug delivery.