Photometric Determination of Itopride Hydrochloride in Its Tablets by Charge-transfer Reaction with Alizarin Red

It was shown that in an alkaline medium of pH 9, a charge-transfer complex, with mole ratio of 1 to 1 is formed between itopride (ITPR) and alizarin red (AZR), having its apparent molar absorptivity of 2.8×103L·mol-1·cm-1. Beer′s law is obeyed in the range of 20 to 80 mg·L-1 of ITPR. This method was applied to the analysis of ITPR tablets. Twenty tablets of the drug were taken and pulverized to fine powder, from which a portion of ca. 1/20 was weighed and taken as sample for analysis. An aliquot of aqueous solution of the sample (25/50 mL) was placed in a 50 mL volumetric flask, 0.45 mL of 0.1 mol·L-1 NaOH solution was added to make the acidity to pH 9.2 and water was added to make up the volume. An aliquot of the solution (with mITPR≤0.40 mg and its volume ≤2.5 mL) was mixed with 2.5 mL of AZR solution (c=5×10-4mol·L-1) and made its total volume to 5.0 mL. After 10 min, its absorbance was measured. The result of ITPR found were in consistency with the value found by the standard method.