Acid-base Titrimetric Assay of Hydroxyzine Dihydrochloride in Pharmaceutical Samples

Two simple titrimetric methods have been developed for the determination of hydroxyzine dihydrochloride (HDH) in pure form and in tablets. The principle of the methods are simple acid-base reactions in which the hydrochloride content of the drug was determined by titrating with an aqueous standardized NaOH solution either visually using phenolphthalein as indicator (method A) or potentiometrically (method B) using glass-calomel electrode system. The methods were applicable over the range of 2-20 mg HDH. The procedures were also applied for the determination of HDH in its dosage forms and the results were found in good agreement with those obtained by the reference method. The precision, expressed by intra-day and inter-day relative standard deviation values, was satisfactory (RSD ≤ 2.76%). The accuracy was satisfactory as well RE ≤ 2.67%. Excipients used as additives in pharmaceutical formulations did not interfere in the proposed procedures as shown by the recovery study via standard addition technique with recovery percentage in the range 97.48 – 106.3% with a standard deviation of 1.76 3.42 %.