Application of Ion-Association Titration for the Assay of Cyproheptadine Hydrochloride in Pharmaceuticals

Two simple and rapid titrimetric methods are described for the determination of cyproheptadine hydrochloride (CPH) in pharmaceuticals. The proposed methods are based on the solvent extraction-titration of CPH with two ion association reagents, sodium lauryl sulphate (SLS), (method A), and tetraphenylborate (TPB), (method B). In method A, SLS was used as titrant and the titration was carried out in the presence of dilute sulphuric acid and chloroform using dimethyl yellow as indicator, whereas, in method B, the titrant was TPB and the titration was done in Walpole buffer of pH 4.5 and 1, 2-dichloroethane using tetrabromophenolphthalein ethyl ester as indicator. The proposed procedures give sharp end points as the color of the organic phase changes from yellow to pink in method A, and from red-violet to yellow in method B. The methods are applicable over the ranges of 1.0–20.0 and 2.0–9.0 mg of CPH for method A and method B, respectively. The accuracy and precision of the methods are good. The methods were applied successfully to the determination of CPH in tablets, and the results were in agreement with the label claim and those of the reference method.