ANALYTICAL STUDY OF SOME ANTIHISTAMINES WITH HAEMATOXYLIN REAGENT

Document Type : Original Article

Author

Department of Pharmaceutical Analytical Chemistry, Faculty of Pharmacy, Assiut University, Assiut, Egypt

Abstract

The reaction between haematoxylin reagent and eight antihistaminic drugs (chlorpheniramine maleate, pheniramine maleate, cyproheptadine hydrochloride; astemizole, terfenadine, ranitidine hydrochloride, famotidine and cimitidine) was investigated and utilized as the basis for a new, simple and sensitive spectrophotometric procedure for their determinations. The procedure is based on the reaction of the methanolic solution of the anti-histaminic compounds with haematoxylin reagent in 3x10-3 M boric acid to give a reddish-violet colour (lmax 555 nm). The absorbance was linear with all compounds over the 5-200 µg/ml general concentration range of the final measured antihistamine base solution. A good correlation was found between log A (1%, 1 cm) and pka values for six of the studied drugs. The method can be applied successfully to the analysis of commercially available tablet formulations. No interference was observed due to additives which are commonly present in tablet formulations or coformulated compounds such as phenazone, phenazone salicylate, sodium salicylate paracetamol, propyphenazone and caffeine.