Formulation of once a day matrix tablet of Venlafaxine Hydrochloride using Polyethylene Oxide

Abstract

The study was conducted to develop once-a-day venlafaxine hydrochloride tablets, which shows dissolution similarity with EffexorÒ XR Capsules. Polyethylene oxide (PEO) is the hydrophilic polymer used to control the drug release. Direct compression, Wet granulation and combination were evaluated. The granules and tablets were characterized. The primary dissolution media was distilled water and the optimized batches were also tested for drug release similarity in 0.1 N HCl, phosphate buffer pH 6.8 and distilled water containing 10% ethanol. Direct compression did not work well due to poor flow and compressibility. PEO has high affinity for water and are fastest hydrating polymer and hence water alone cannot be used for granulation. Uncoated tablets prepared by wet granulation with isopropyl alcohol and water exhibited burst drug release. Hence tablets were coated with ethyl cellulose and hypromellose to get required drug release. To avoid use of isopropyl alcohol, venlafaxine HCl was granulated with water and then PEO was added extragranularly. Thus Isopropyl alcohol can be eliminated from the formulation which reduces the cost and regulatory requirements of analysis of residual solvents. The optimized batch showed required granular and tablet characteristics. It showed comparable drug release at different pH and the formulation was stable. The use of radar diagrams was demonstrated.