Valsartan release from sustained release matrix tablet and effect of cellulose derivatives

The present study was aimed to develop antihypertensive sustained release matrix tables of valsartan Angiotensin II receptor antagonist, using hydroxypropylmethylcellulose alone and in combination with ethyl cellulose as the matrix material in different proportion by wet granulation method. The granules were evaluated for angle o f repose, bulk density and Compressibility index. The tablets were subjected to weight variation test, drug content, hardness, friability, and in vitro release studies. The granules showed satisfactory flow properties, compressibility, and all the tablet formulat ions showed acceptable pharmacotechnical properties. The formulated tablets also compared with a marketed product. In vitro dissolution studies indicate that EC significantly reduced the rate of drug release compared to HPMC. But no significant difference was observed in the release profile of matrix tablets made by higher percentage of EC. The result of d issolution study indicate that the fo rmulat ion prepared by low viscosity grade HPMC (H1and H2) showed maximum drug release up to 8 hrs and high v iscosity gread HPMC and EC formulat ion (H3 to H6) showed upto 12 hrs. In case of formulat ion containing combination of HPMC and EC (F1 to F4) prepared using factorial design, showed drug release up to 24 hrs, whereas marketed product was found to be release up to only 3 hrs.Methematical treatment of the in vitro drug release data suggest that, optimized formulation F3 fitted in to Korsmeyer and Peppas release kinetic shows R 2 value 0.9930. Drug release from the matrix occurred by combination of two mechanism, diffusion and erosion of tablet. Key-Words: Valsartan, HPMC, EC, Sustained Release, Matrix Tablet Introduction Valsartan is an angiogenesis II receptor antagonist that is used for the treatment of hypertension. It treat the hypertension by blocking the vasoconstrictor and aldosterone secreting effect of angiotensin II selectively by blocking the binding of angiotensin II and angiotensin1 receptor in many tissues. The most preferred route for this drug is oral delivery in form of tablets. Valsartan have poor water solubility, low bioavaibility (approximately 20-25%), and shorter halflife (nearly 6 hours) 1-2 . Oral drug delivery has been known for decades as the most widely utilized route of administration among all the routes that have been explored for the systemic delivery of d rugs via various pharmaceutical products of different dosage forms. The reason that the oral route achieved such popularity may be in part attributed to its ease of admin istration as well as the traditional belief that by oral admin istration the drug is as well absorbed as the food stuffs that are ingested daily 3 . * Corres ponding Author The conventional dosage form such as tablets and capsules are the major oral preparations conventional dosage form have wide acceptance up to 50-60% of total dosage forms. Solid dosage forms are popular because of ease of admin istration, accurate dosage, self-medicat ion, pain avoidance and most importantly the patient compliance in last two decades the drug delivery technology has been developed rapidly and many novel oral d rug delivery systems have been invented 4 . Oral drug delivery has been the most widely utilized route of administration among the all route because of certain advantages such as unit dosage form, low cost, cheapest for packaging etc. apart from these advantages this route suffers from certain drawbacks like patient noncompliance, multip le dosing, therapeutic failure that limits its use. In order to overcome these drawbacks of conventional drug delivery there is a need of development of new drug delivery system or modified drug delivery system 3 . Sustained release system is a type of modified drug delivery system that can be used as an alternative to conventional drug delivery system. These systems Research Article [Mahajan et al., 2(1):Jan., 2011]