Improved dissolution rate of indomethacin by adsorbents.

Samples of indomethacin and kaolin or microcrystalline cellulose (Avicel) were prepared by solvent deposition or simple blending methods. Dissolution rates of these samples were studied. The surface adsorption of indomethacin on the studied adsorbents was shown to improve the dissolution rate of the drug in water. The solvent-deposited samples of indomethacin on kaolin or Avicel in the ratio 1:4 released 25% of the drug at 34 or 60 min, respectively (t25%), while 25% of the pure drug was released at 140 min. Meanwhile, the t25% of the corresponding drug-adsorbent simple blends were 108 and 110 min, respectively. The effect of addition of polyvinyl pyrrolidone (PVP) as a third component to indomethacin-adsorbent was studied and showed further improvement in in vitro availability of the drug-kaolin adsorbents.

Preparation and evaluation of slow-release pan-coated indomethacin granules.

Granules containing indomethacin crystals are coated with Eudragit solutions of different RL/RS ratios using a pan coating technique. The process is reproducible with regard to drug content, inexpensive and the formed granules were directly compressed into tablets. In vitro release of indomethacin from coated granules, tablets and capsules was studied as a function of different ratios of Eudragit RL/RS in the coating solution. The release of the drug was significantly reduced by the coating process in comparison with a formulation made from uncoated granules, prepared using 10 per cent gelatin solution as a binder. Release data were found to follow a diffusion-controlled model.

Preparation and in vitro evaluation of slow release ketoprofen microcapsules formulated into tablets and capsules.

Ketoprofen powder was encapsulated with Eudragit RL/RS polymer solutions in isopropanol-acetone 1:1, using a simple and rapid method. Microcapsules were prepared using Eudragit solutions with different RL/RS ratios. The encapsulation process produces free-flowing microcapsules with good drug content and marked decrease in dissolution rate. The retardation in release profile of ketoprofen from microcapsules was a function of the polymer ratio employed in the encapsulation process. In vitro release of ketoprofen from microcapsules either filled in gelatin capsules or compressed into tablets, using calcium sulphate as diluent, confirmed the efficiency of the encapsulation process for preparing prolonged release medication. A capsule formulation with optimum sustained-release profile was suggested.

The application of solid dispersion technique in the preparation of therapeutic tablets. Part 1: Paracetamol, amylobarbitone, and caffeine tablets.

A trial was made to study the possibility of preparing high-quality therapeutic tablets by direct compression of the solidified drugcarrier melt via solid dispersion technique. Paracetamol-mannitol, amylobarbitone-urea and caffeine-nicotinamide systems were investigated. Phase diagrams of the first two systems were found to be of the simple eutectic type, while that of the third system was a peritectic type. Solubility studies were also carried out. Dissolution rate studies showed that the fused mannitol/paracetamol (80:20), urea/amylobarbitone (80:20) and nicotinamide/caffeine (50:50 and 70:30) solid dispersions exhibited better rates of dissolution than those of the pure drugs. Comparative studies were carried on with tablets prepared by direct compression of the drug-carrier solidified melt exhibiting the highest dissolution rate and by slugging the pure drug and the drug-carrier physical mixture of corresponding composition. The physical properties and dissolution rate data showed the superiority of the tablets prepared by the solid dispersion technique. The drug release from these tablets was 4.5, 7.6 and 3.7 times greater than that from tablets prepared from pure paracetamol, amylobarbitone and caffeine respectively.