Available online at www.scholarsresearchlibrary.com Scholars Research Library Der Pharmacia Lettre, 2015, 7 (7):148-157 (http://scholarsresearchlibrary.com/archive.html) ISSN 0975-5071 USA CODEN: DPLEB4 148 Scholar Research Library Formulation development and evaluation of metoprolol succinate sustained release tablets using 3 2 factorial design J. N. Suresh Kumar 1 , B. Satyaprasad 2 , Gunji. Venkateswarlu 3 , Chandan Kumar Brahma 1 and Raghavendra Kumar Gunda 1 * 1 Department of Pharmaceutics, Narasaraopeta Institute of Pharmaceutical Sciences, Narasaraopet, Guntur (Dt), Andhra Pradesh, India 2 Department of Pharmaceutical Analysis, Narasaraopeta Institute of Pharmaceutical Sciences, Narasaraopet, Guntur (Dt), Andhra Pradesh, India 3 Department of Pharmacognosy, Narasaraopeta Institute of Pharmaceutical Sciences, Narasaraopet, Guntur (Dt), Andhra Pradesh, India _____________________________________________________________________________________________ ABSTRACT The main objective of present investigation is to formulate the sustained release tablet of Metoprolol Succinate using 3 2 factorial design. Metoprolol Succinate, is a selective β 1 blocker, to treat Hypertension & Heart Failure. The SR tablets of Metoprolol Succinate were prepared employing different concentrations of HPMCK15M and HPMCK100M in different combinations as a rate retardants by Direct Compression technique using 3 2 factorial design. The quantity of rate retarders, HPMCK15M and HPMCK100M required to achieve the desired drug release was selected as independent variables, X 1 and X 2 respectively whereas, time required for 10% of drug dissolution (t 10% ), 50% (t 50% ), 75% (t 75% ) and 90% (t 90% ) were selected as dependent variables. Totally nine formulations were designed and are evaluated for hardness, friability, thickness, % drug content, In-vitro drug release. From the Results it was concluded that all the formulation were found to be with in the Pharmacopoeial limits and the In- vitro dissolution profiles of all formulations were fitted in to different Kinetic models, the statistical parameters like intercept (a), slope (b) & regression coefficient (r) were calculated. Polynomial equations were developed for t 10% , t 50% , t 75% , t 90%. Validity of developed polynomial equations were verified by designing 2 check point formulations(C 1 , C 2 ). According to SUPAC guidelines the formulation (F 5 ) containing combination of 10% HPMCK15M and 10% HPMCK100M, is the most similar formulation (f 2 =92.38 & No significant difference, t= 0.0216) to marketed product (Metocard). The selected formulation (F 5 ) follows Higuchi’s kinetics, the mechanism of drug release was found to be Super case II transport (Non-Fickian, n= 0.981). Keywords: Metoprolol Succinate, Factorial Design, Sustained Release Tablet, HPMCK15M, HPMCK100M, Non Fickian Mechanism, Super Case-II Transport. _____________________________________________________________________________________________ INTRODUCTION Oral administration is the most convenient, widely utilized for both conventional and novel drug delivery systems, and preferred route of drug delivery for systemic action. Tablets are the most popular oral solid formulations available in the market and are preferred by patients and physicians alike. There are many obvious reasons for this, not the least of which would include acceptance by the patient and ease of administration . In long-term therapy for the treatment of chronic disease conditions, conventional formulations are required to be administered in multiple doses and therefore have several disadvantages [1]. However, when administered orally, many therapeutic agents are subjected to extensive presystemic elimination by gastrointestinal degradation and/or first pass hepatic metabolism as a result of which low systemic bioavailability and shorter duration of therapeutic activity and formation of inactive or toxic metabolites [2].