Effect of Processing and Polymer Variables on Invitro Release of Metoprolol Succinate Extended Release Tablets

The present study was aimed to develop an extended release tablet of Metoprolol Succinate for the treatment of hypertension. Four extended release formulations F1-F4 were developed using varying proportions of Hydroxyl propyl methyl cellulose K100M, Sodium carboxy methyl cellulose and Eudragit L30 D55 by wet granulation. Five extended release formulations F5-F9 containing HPMC K100M and HPMC 5cps in varying concentration were developed by direct compression. The physico-chemical and in-vitro release characteristics of all the formulations were investigated and compared. Two formulations, F7 and F8 have shown not more 25% drug release in 1 h, 20-40% drug release at 4 h, 40-60% drug release at 8 h and not less than 80% at 20 h and the release pattern conform with USP specification for 24 h extended release formulation. It can be conclusively stated that optimum concentration of HPMC K100M (58-65%) by direct compression method can yield an extended release of Metoprolol succinate for 24 hours. INTRODUCTION: Conventional oral drug delivery systems are slowly fading away in the market owing to disadvantages. These delivery systems produce fluctuation of drug plasma level that either exist at safe therapeutic level or quickly falls below the minimum effective level. This effect is usually totally dependent on the particular agent’s biological half life, frequency of administration and release rate. It is recognized that many patients can benefit from drugs intended for chronic administration by maintaining the plasma level within a safe effective range . Extended oral drug delivery systems are highly recognized today for their benefits improving the disadvantages of conventional drug delivery systems. To be a successful extendedrelease product the drug must be released from the dosage from at a predetermined rate in gastrointestinal fluids, maintain sufficient gastrointestinal residence time and be absorbed at a rate that will replace the amount of drug being metabolized and excreted. Extended drug delivery systems are used in the treatment of chronic rather than the acute condition, and they process a good margin of safety . Metoprolol succinate is a cardio selective β-blocker used in the treatment of hypertension, angina pectoris and heart failure. It is available commercially in 25 mg, 50 mg strength as immediate release tablets. Its half life is about 3 to 7 hours. Its bioavailability is 50% following oral administration. It has been reported that conventional dosage forms increase the plasma concentration of Metoprolol above that achieving the