Study of Moisture Absorption by Ranitidine Hydrochloride: Effect of % RH, Excipients, Dosage Forms and Packing Materials S.M. Ashraful Islam 1 , Md. Amir Hossain 1 , A.N.M. Hamidul Kabir 2 , Shaila Kabir 3 and Md. Khalid Hossain 3 1 Department of Pharmacy, The University of Asia Pacific, Dhaka-1209, Bangladesh 2 Department of Applied Chemistry & Chemical Technology, University of Dhaka, Dhaka-1000, Bangladesh 3 Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Dhaka, Dhaka-1000, Bangladesh ABSTRACT: Moisture absorption by ranitidine at three different level of relative humidity (RH) has been studied. Percentage of moisture absorption at 22%, 57% and 75% RH was 0.6%, 3.1%, and 4.9% respectively. Ranitidine blended with various excipients (maize starch, lactose, avicel PH-101, mannitol, povidone K-30, magnesium stearate and purified talc) were also exposed to 75% relative humidity (% RH) to observe their effects on moisture absorption. Moisture absorption by ranitidine was either increased or decreased when ranitidine was mixed with various diluents, binders and lubricants. Ranitidine mixed with lactose, aerosil-200 and avicel PH-101 absorbed minimum amount of moisture while ranitidine mixed with maize starch absorbed maximum. On the other hand, ranitidine mixed with mannitol was found to absorb intermediate amount of moisture. Ranitidine mixed with povidone K-30 absorbed almost double moisture than pure ranitidine. Ranitidine mixed with purified talc and magnesium stearate absorbed almost same amount of moisture. The type of dosage form and type of packing materials also influenced moisture absorption. Uncoated tablets absorbed maximum amount of moisture (4.5%) while coated tablets absorbed minimum (2%). On the other hand, capsule was found to absorb intermediate amount of moisture (3.4%). PVC-Alu foil packed uncoated ranitidine tablet absorbed more moisture (3.3%) than that of Alu-Alu packed uncoated ranitidine tablet (0.16%). Key words: % RH, ranitidine hydrochloride, moisture, absorption INTRODUCTION Moisture plays remarkable negative role in pharmaceutical product, particularly for solid dosage forms. Both physical and chemical stability of some drugs are affected by moisture. Moisture is absorbed on the surface of solid drugs and increases the rate of decomposition, causes agglomeration and dissolution of drugs. 1 Correspondence to: Md. Khalid Hossain Tel: 880-2-9661920-79, Ex-144; Fax: 880-2-8612069 E-mail: hossainkhalid2004@yahoo.com Dhaka Univ. J. Pharm. Sci. 7(1): 59-64, 2008 (June) Presence of moisture possesses a critical challenge on drug stability. Moisture accelerates the hydrolysis of drug as well as facilitates reaction with other excipients, thereby affecting stability and shelf life of the final product. The effect of moisture absorption on the shelf life of coated tablets has been reported previously. 2 Generally, the initial moisture level as well as the inherent tendency of the active ingredients and excipients to uptake water from the surrounding environment governs the moisture absorption pattern of the final product. The hygroscopic nature of excipients and active ingredients should be considered in designing the formulation. Water sorption or desorption by drugs