Development and evaluation of a multiple-unit oral sustained release dosage form for S(+)-ibuprofen: preparation and release kinetics.

Mini-matrix tablets containing S(+)-ibuprofen have been prepared by the wet granulation method. The hydrophilic matrix was formed with either xanthan gum, karaya gum or hydroxymethylcellulose (HPMC) together with a choice of additives from lactose, Encompress(R), Avicel(R) PH101, talc and Lubritab(R). Multiple unit dosage forms (MUDFs) were subsequently obtained by encapsulating the mini-matrix tablets into hard gelatin capsules. Preparation, in vitro release profiles and release kinetics are presented.

Relationship between swelling, erosion and drug release in hydrophillic natural gum mini-matrix formulations.

The swelling, erosion and solvent front penetration properties of mini-matrices containing xanthan (X), locust bean (LB) and karaya (K) gums were examined, analysed and related to the overall in vitro release kinetics of diclofenac sodium, used as a model drug. Mini-matrices were produced with drug:gum ratios of 1:1 as well as formulations of drug and X in combinations of 2:1, 2:3 and 1:2. The rank order of decreasing swelling index (SI) in both axial and radial dimensions was X?K?LB and each gum showed almost Fickian swelling behaviour. The solvent front penetration rates were consistent with the rates of swelling. However, the order of decreasing drug release and erosion rates was LB>X>K and all formulations demonstrated anomalous (non-Fickian) drug release kinetics. Therefore Fickian drug diffusion and polymer erosion were both occurring simultaneously. The dominant mechanism depended on the nature and content of the gum, as well as the stage in the dissolution time period. There was a loss of matrix integrity in formulations containing a high drug:gum ratio.