Preliminary formulation studies of water-soluble granules of Hibiscus sabdariffa calyx

Background: The formulation of Hibiscus sabdariffa, a plant reported to have hypoglycemic, antihypertensive, antibacterial, antioxidant and anti-inflammatory properties, into a suitable dosage form is vital in improving patient compliance and maximizing its benefits. Objectives: This study aims to formulate water-soluble granules from the calyx of Hibiscus sabdariffa using three (3) different granulating fluids and characterize the formulated granules to obtain an optimized formulation. Methods: Dried calyces of Hibiscus sabdariffa were pulverized and formulated into granules via the wet granulation technique using three different granulating fluids: xanthan gum mucilage (2 %), glucose solution (50 %), and syrup BP. Granule flow properties and solubility were determined. Interactions were monitored using Fourier transform infrared (FT-IR,), while morphological attributes were assessed using X-ray powder diffraction (XRD) and scanning electron microscopy. Results: The mean granule diameter of the granules was between 700 and 740 µm, and the moisture content was between 0.7 and 1.3 % with sucrose-based granules having the least amount of moisture. All batches had excellent flow. The insoluble particles and aqueous dispersibility were between 2.20 and 4.45 g and 158.67 and >2400 sec, respectively. Glucose-based granules were more soluble and easily dispersible. FT-IR showed no interaction between the granulating fluids and hibiscus calyces, while XRD of the optimized formulation (glucose-based granules) revealed decreased crystallinity. Conclusion: Glucose solution (50%) is considered the most suitable fluid for the formulation of water-soluble granules of Hibiscus sabdariffa calyces. This study demonstrates the potential of formulating an acceptable oral dosage form from the calyces of Hibiscus sabdariffa using a 50% glucose solution as a granulating fluid, yielding optimal granule properties that will enhance product acceptability and patient compliance.