Preparation and characterization of Compritol 888 ATO matrix tablets for the sustained release of diclofenac sodium.

The preparation of lipophilic matrix tablets for the sustained release of water soluble drugs via direct compression is not always feasible due to poor flow and rapid drug release. The aim was to evaluate the potential for developing sustained-release diclofenac sodium tablets, using Compritol® 888 ATO as a lipid matrix, by a wet granulation technique. The effects of wet granulation method (planetary mixer and fluid-bed) and liquid binder type (HPMC Metolose® 603, 606 or 615) on weight uniformity, tensile strength and release rates were investigated. The influence of compression force and speed during tablet manufacture under simulated rotary press production conditions were also evaluated. Rapid release of diclofenac sodium from directly compressed matrices was observed. A wet granulation technique using different HPMC binders produced free-flowing granules and matrices which released diclofenac sodium in a sustained manner over several hours. When the formulation comprising the lowest viscosity grade HPMC (Metolose® 603) was further evaluated using a laboratory scale fluid-bed system, consistently sized granules with good flowability and matrices with good weight uniformity and tensile strengths were produced. Release rates were consistent over a range of compression speeds and forces indicating the suitability of the formulation for production on a rotary tablet press.