The work presented herein discusses the carboxymethylation of sorghum starch which improved its
physicochemical properties for a potential pharmaceutical application as an excipient in tablet formulations. Sorghum
(sorghum bicolor) starch was extracted from sorghum cereal using 0.075% (w/v) sodium metabisulphite and it gave a yield
of about 80.4% on dry weight basis. The starch was chemically modified via carboxymethylation and characterized. SEM
of the native starch showed irregular shape while the modified starch has regular shape and fibrous long distort shape.The
X-ray Diffractogram revealed that the native and modified starches are completely amorphous in nature.The major
functional groups in the native starch were 1736cm-1 (C=O), 1625cm-1 (-COO-), 1427cm-1 (-COO-), 1227cm-1 (-C=O-),
1162cm-1 (C-O stretching and C-H stretching).During carboxymethylation there were introduction of new functional
groups, 1800-1500cm-1 (-COO-) and 1606-1632cm-1 (OCH2COONa) respectively.The physicochemical properties
investigated includes:The moisture content was obtained for the Native Starch (NVS) (5.46±0.00), and Carboxymethyl
Starch (CMS) (5.23±0.00). Overall the moisture content of the starch (unmodified and modified) compared favourably
with the minimum standard ≤ 15% for good quality starch. The pH of NVS is (7.00±0.01), CMS (6.64±0.02). They are all
similar to maize starch. Relative viscosity of NVS is (1.70±0.08), CMS (2.30±0.08). Water holding capacity was obtained
for NVS (28.35±0.20), CMS (39.35±0.20). Modified starch improved in water holding capacity.These physicochemical
analyses have shown that modification improved the physical nature of the native starch.The flow properties of the
granules show low angles of repose, high flow rate due to lower cohesive forces, hence good flow and better tabletting
properties. The tablets were evaluated for quality control such as weight, friability, crushing strength, diameter, thickness,
disintegration, in vitro dissolution, and drug excipient interactions.