The Use of Chloranilic Acid for the Spectrophotometric Determination of Three Antihistamines∗

The three antihistaminic drugs investigated are of diverse chemical types, and many chemical methods have been reported for their assay. Cyproheptadine hydrochloride (CPH) is a serotonin and a histamine antagonist with anticholinergic and sedative effects. It also blocks voltage sensitive calcium channels in pancreatic islet cells and smooth muscle. CPH is also used as an appetite stimulant to assist weight gain. The majority of methods found in the literature for the determination of cyproheptadine were devoted to biological materials. Methods for the assay of the drug in pharmaceutical preparations are few and include uv-spectrophotometry , visible spectrophotometry 2−4, ion-selective electrode based potentiometry, gas chromatography and high performance liquid chromatography9−11, though the last two techniques are not always widely available. Methdilazine hydrochloride (MDH) belongs to the phenothiazine class of drugs. Medicinally, it has been used as an antihistamine and it is also found to possess antipruritic action. Several spectrophotometric ∗Presentation at the XX Conference of Indian Council of Chemists held in December 2001 at Mysore. †Corresponding author