Comparative evaluation of properties of paracetamol tablets formulated with three local starches as binders

Abstract

This study was carried out to comparatively evaluate the tableting and release characteristics of paracetamol tablets prepared with three indigenous starches as binder. These parameters were compared with those tablets prepared with Maize starch BP as standard. Starches currently being used in pharmaceutical industry are largely imported into the country, hence there is the need to source for some indigenous starches whose binding properties would sufficiently ameliorate the brittle fracture tendency that has been a major problem in tableting. Starches from African bitter yam (Dioscorea dumetorium), cocoyam (Colocasia esculenta) and cassava (Mannihot utilissama) tubers were extracted and characterized with Maize starch BP as standard. Their true particle densities were determined with the specific gravity bottle method. Viscosities of the starch mucilage were also determined. The mucilage of each of these starches was used as binder at concentrations (1, 1.5, 2 and 2.5% w/w) per tablet in the formulation of paracetamol granules. The granules were compressed to tablets with and without a centre hole at varying compression loads (3, 4 and 5 arbitrary units). The tablets were flat faced with mean diameter of 12.1 ± 0.02 mm and mean thickness 4.1 ± 0.02 mm. The tablets’ tensile strength (T), brittle fracture index (BFI), packing fraction (P_f), disintegration time (DT) and dissolution profiles were determined. The centre hole in the tablet served as a model defect to represent void that are formed in the tablet during compression due to air entrapments. The results showed that there was no statistically significant difference in the physicochemical characteristics of the tablets whose granules were prepared with the 3 test starches and those prepared with the standard maize starch BP (p > 0.05). There was a general increase in the tablet viscosities as the mucilage concentration increased. Cassava starch mucilage was more viscous hence expected to impact more plasticity to the granules. Tablet tensile strength (T) increased with increase in the binder concentration but was more marked with tablets produced with cassava starch mucilage. At all m binder concentrations, cassava starch produced tablets with lowest BFI and highest Pf compared to the other starches including maize starch BP. Increase in compression load resulted in tablets with increase in T, BFI, Pf and DT. The increase in BFI is attributed to increase in die wall stress on the tablet at the point of ejection during compression. All the tablets released between 79.2 - 89.6% of the drug in 45 min. Although drug release was influenced by increase in binder concentration, the release rate was nevertheless significantly affected by the types of starch binders under investigation. The results permit the conclusion that the three (3) sourced indigenous starches (African bitter yam, cocoyam and cassava) could be substituted for maize starch BP as binder in the preparation of paracetamol tablets.

Keywords: Cassava starch, African bitter yam starch, cocoyam starch, binder, tablet properties, paracetamol