ASIAN JOURNAL OF CHEMISTRY ASIAN JOURNAL OF CHEMISTRY http://dx.doi.org/10.14233/ajchem.2016.19312 Hydroxyzine is a first-generation antihistamine belongs to diphenylmethane and piperazine class of drug [1] (Fig. 1). It shows its antagonistic effects on several receptor systems in the brain, it has a strong anxiolytic and mild antiobsessive as well as antipsychotic properties [2]. It is used for the symptomatic relief of tension and anxiety associated with psychoneurosis and in organic disease states in which anxiety is manifested used as an adjunct. Because of its antihistamine effects it can also be used for the treatment of severe cases of hyperalgesia, itching and nausea due to motion sickness. This drug has also been used in some cases to relieve the effects of opioid with- drawal [3]. It is also an effective sedative, anxiolytic and hypnotic, it allegedly shares virtually none of the abuse, addiction, depen- dence and toxicity potential of other drugs used for the same reason therapeutically. Hydroxyzine has also been used to potentiate the analgesia of opioids and to alleviate some of their side effects, such as itching, nausea and vomiting [4]. Cetirizine the second-generation antihistamine is in fact one of the metabolites of hydroxyzine produced in the human body. Unlike hydroxyzine, cetirizine is not reported to cross the blood- brain barrier. However it has been reported to be associated with dystonic reactions as well as sedation [5]. In this study the drug substance is exposed to acid and base stress testing for the evalua- tion of degradation of a drug substance. The drug is exposed to basic or acidic medium over a period of time to obtain its primary degradation products. Carbonyl functional groups which are imines, amides, aryl amines, imides, esters, carbamates and alcohols are more prone to acid/base hydrolysis. NOTE Study of Effect of Acidic and Basic Medium on Hydroxizine by UV Spectroscopy SAFILA NAVEED 1,* , FATIMA QAMAR 1,* , S. SARAH ABBAS 1,2 , NIMRA WAHEED 1 , ZEHRA ASHRAF 1 , MAHEEN NAFEES 1 , HAMEEZ JAWED 1,2 and SYEDA ZAINAB 2 1 Faculty of Pharmacy, Jinnah University for Women, Karachi, Pakistan 2 Faculty of Pharmacy, University of Karachi, Karachi, Pakistan *Corresponding authors: E-mail: safila117@yahoo.com; fatimamudassar2009@hotmail.com Received: 5 May 2015; Accepted: 28 November 2015; Published online: 30 December 2015; AJC-17719 In this work, the effect of different environmental conditions by subjecting the pharmaceutical formulation i.e., hydroyzine under acidic and basic conditions are studied by using spectrophotometer. When hydroxyzine subjected to 0.1 N HCl and 0.1 N NaOH, hydroxyzine showed increased availability in acidic medium and decreased availability in alkaline medium. Keywords: Hydroxyzine, Acidic medium, Basic medium, Degradation, UV spectrophotometer. Asian Journal of Chemistry; Vol. 28, No. 4 (2016), 933-934 N N O OH Cl Fig. 1. Absorbance of hydroxyzine The aim of the study is to evaluate the effect of different environmental conditions by subjecting the pharmaceutical formulation i.e. hydroyzine under acidic and basic conditions by using spectrophotometer. It is usually preferred over other methods because of less equipment cost and economical maintenance advantage. All glasswares were washed with chromic acid then with water and finally rinsed with freshly prepared double distilled water. Reagents were of analytical grade reagents. Ultraviolet Lamp Power of 8N, Serial No. N 045571, LF-204.LS ‘4W-254 and 365 nm’, spectrophotometer with a quartz cuvette T80 UV-VI spectrometer ‘PG Instrument’, Weighing Balance Item PA214C: ‘Pioneer OHAIUS’ and Water Bath ‘HH-4’ having digital and constant temperature tank. Preparation of 0.1 N HCl and 0.1 NaOH: 4 g of NaOH is transferred in 100 mL volumetric flask and dissolved in small quantity of water and finally volume was made up to