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M. Bamba, F. Puisievx, J. P. Marty and J. T. Carstensen, “Release Mechanism in Gel Forming Sustained Release Formulations,” International Journal of Pharmaceutics, Vol. 2, No. 5-6, 1979, pp. 307-311. doi:10.1016/0378-5173(79)90037-1

has been cited by the following article:

• TITLE: Development and Optimization of Venlafaxine Hydrochloride Sustained Release Triple Layer Tablets Adopting Quality by Design Approach

  AUTHORS: Shital Bhavin Butani

  KEYWORDS: Venlafaxine HCl; Polyethylene Oxide; Xanthan Gum; Triple Layered Tablets

  JOURNAL NAME: Pharmacology & Pharmacy, Vol.4 No.3A, June 24, 2013

  ABSTRACT: Purpose:Venlafaxine hydrochloride sustained release formulation increases patient compliance by reducing frequency of administration and it also reduces side effects like nausea and vomiting. Hence the objective of present investigation was to develop triple layer sustained release tablets of venlafaxine HCl using xanthan gum or polyethylene oxide. Methods:The venlafaxine HCl 150 mg sustained release tablets were prepared by wet granulation technique where drug was incorporated in middle layer with part of polymer. The barrier layers were composed of remaining polymer and other excipients. The granules and tablets were characterised. Optimized batches were also tested for drug release at different pH and in presence of ethanol, for kinetics of drug release and for water uptake/swelling. Results: Preliminary trials of monolayer tablet showed burst release due to high dose and solubility of venlafaxine HCl and hence triple layer tablets were developed. Granules of middle layer exhibited good flow properties. The comparative drug release to Effexor? XR capsule 150 mg could be achieved by modulating the concentration of polymer and diluents in middle layer as well as in barrier layers. Higher amount of polyethylene oxide was required as compared to xanthan gum which may be due to high water uptake and poor gel strength of polyethylene oxide. The optimized formulations showed pH independent drug release as well as ethanol had no effect on drug release. Effexor? XR capsule and optimized batches followed Weibull kinetics for drug release. The radar diagrams showed the comparable drug release to innovator in both the optimized formulations but point to point correlation was observed in batch with xanthan gum. Conclusion: The layered matrix tablets formulated successfully using hydrophilic polymers, xanthan gum or polyethylene oxide, to sustain the release of highly soluble drug like venlafaxine HCl.