Int. J. Pharm. Sci. Rev. Res., 56(2), May - June 2019; Article No. 14, Pages: 94-101 ISSN 0976 – 044X International Journal of Pharmaceutical Sciences Review and Research Available online at www.globalresearchonline.net © Copyright protected. Unauthorised republication, reproduction, distribution, dissemination and copying of this document in whole or in part is strictly prohibited. 94 M. Rajesh* 1 , I. Meeranmydeen 2 , R. Venkatesh Babu 3 * 1 Department of Pharmaceutics, Sankaralingam Bhuvaneswari College of Pharmacy, Sivakasi, Tamil Nadu, India. (Affiliated to the Tamilnadu Dr.M.G.R. Medical University, Chennai, India.) 2 Department of Pharmaceutics, S.A Raja Pharmacy College, Vadakangulam, Tamil Nadu, India. 3 Research and Development Department, Pharmafabrikon Unit II, 91- 1, Sivagangai Road, Vilathur, Madurai, Tamil Nadu, India. *Corresponding author’s E-mail: mrajeshpharm@gmail.com Received: 22-04-2019; Revised: 26-05-2019; Accepted: 04-06-2019. ABSTRACT Duloxetine hydrochloride is an acid labile antidepressant drug which degrades in acidic environment. The study was aimed to formulate enteric coated tablets of Duloxetine hydrochloride using (Protectab enteric M1) to avoid degradation in the stomach and to improve the therapeutic efficiency. Five formulations (F-I to F-V) were prepared by direct compression method, without & with addition of calcium carbonate as an alkalizing agent. Prepared tablets were evaluated for various post compression parameters. Among the formulations, the drug release of F-I formulated without addition of calcium carbonate, F-II & F-III prepared with 5mg & 15mg of calcium carbonate were not within the I.P limit. So in F-IV and F-V, calcium carbonate concentration was increased to 25 mg & 30 mg which showed drug release of 95.78% and 100.67% at 45 min which was within the I.P limit. Hence F-IV & F-V formulations were selected for enteric coating and F-IV formulation was coated with 4% Protectab enteric M1 polymer(E-IV), and F-V was coated with 8% Protectab enteric M1 polymer(E-V). Formulation E-IV fails in the disintegration test and Formulation E-V passed the disintegration test of the enteric coated tablets. Hence E-V was selected as a best formulation which showed better drug release compared to marketed drug and stability study revealed, E-V formulation was stable even after stored at 25±2°C/60%±5%RH and 40±2ºC/75%±5%RH for a period of 3 months. Hence the study concluded that formulation E-V satisfied all the criteria for enteric coated tablets. Keywords: Calcium carbonate, Duloxetine Hydrochloride, Enteric coated tablets, Stability study. INTRODUCTION uloxetine hydrochloride is one of the most commonly used antidepressant drug which is a selective serotonin and norepinephrine reuptake inhibitor (SSNRI) used to balance the harmones such as dopamine, serotonin and norepinephrine. 1 Duloxetine hydrochloride is an acid labile drug which degrades in acidic environment of the stomach thus leading to therapeutic inefficiency. The study was aimed to formulate enteric coated tablets of Duloxetine hydrochloride using methacrylic acid copolymer (Protectab enteric M1) to avoid degradation and to bypass the acidic pH of the stomach, to improve the therapeutic efficacy and to increase the Duloxetine release in the intestine compared to the marketed Duloxetine hydrochloride enteric coated tablet. 2 Five formulations (F-I to F-V) were prepared by direct compression method without & with addition of calcium carbonate as an alkalizing agent. Best formulation was taken and coated with enteric polymer and the drug release of the formulation was compared with marketed enteric coated tablet of Duloxetine hydrochloride. MATERIALS AND METHODS Materials Duloxetine hydrochloride was obtained from MetroChem API Pvt. Ltd, Hyderabad, India. Mannitol anhydrous was procured from Shandong Tianli Pharmaceutical Co. Ltd, China. Microcrystalline cellulose-PH 112 was procured from Accent Microcell Pvt. Ltd, Gujarat, India. Calcium carbonate was procured from Par Drugs and Chemicals Pvt. Ltd, Vadodara, India. Povidone-K30 from Boai NKY Pharmaceuticals Ltd, China, Croscarmellose sodium from Prachin Chemicals Pvt. Ltd, Ahmedabad, India, Instacoat moist shield and Insta coat glow from Ideal Cures Pvt. Ltd, Mumbai, India and Protectab Enteric MI polymer was procured from Bharat Coats, Chennai, India. All other chemicals and reagents used were of analytical grade. Methods Preformulation Studies Preformulation can be defined as an investigation of physical and chemical properties of drug substance alone and when combined with excipients. It is the first step in the rational development of dosage forms. 3 Organoleptic properties The organoleptic property like color, odor and taste of the API was evaluated. A small quantity of Duloxetine HCl was taken in a butter paper and the colour was viewed in well-illuminated place. Very less quantity of Duloxetine HCl was used to assess the taste with the help of tongue as well as smelled to get odor. Formulation and Evaluation of Enteric Coated Tablets of Duloxetine Hydrochloride D Research Article