Enhancement of dissolution using multiparticulates
About 40% of the drug compounds are poorly water soluble1. This poor water solubility results in decreased rate and extent of dissolution and hence bioavailability. The formulation of a dosage form for these compounds is a challenging aspect. A number of techniques like micronization, nanonization, salt formation, complexation, solid dispersions, and use of different polymorphic form of the drug are being tried to improve the water solubility of drug compound. Each technique has its own limitations. They cannot be applied to all the drugs. For example, micronization or nanonization are applicable only if the drug compound shows particle size dependent solubility. For the salt formation, a reacting group must be present. Out of all these techniques, solid dispersions are proven to be a right choice for increasing the dissolution of a drug. A number of reports are available for improving the dissolution of drug by solid dispersions. But, it has its own limitations like expensive methods of preparation, difficulty in formulating into a dosage form and scale up of manufacturing process and stability1. Only 2 products have been marketed since the introduction of solid dispersions forty years ago1. This shows the difficulty in commercialization of this technology. In view of this, alternate technologies which are commercially viable are being in development. One such technology is the deposition of drug and carrier on to a sugar sphere. These spheres can be encapsulated or compressed into a tablet. This concept of coating on to sugar spheres (multiparticulates) is being applied to formulate the dosage forms for sustained, controlled or timed or modified drug release profiles. This can also be extended to increase the extent and rate of dissolution of drug. It has an added advantage that effect of food on the absorption of drug can be minimized as these multiparticulates are freely flowing in the gastro intestinal tract. These pellets can be developed by coating the drug and carrier solution on to a non-pareil seed or sugar sphere using a conventional or fluidized coating (Wurster coating) equipment or alternatively these pellets can be formed by extrusion-spheronization technique. By either way, one can expect the increase in dissolution of drugs by selecting a suitable carrier. Sporanox oral capsules developed by Janssen Pharmaceutica which contains Itrocanzole coated by HPMC is the example of marketed product developed by this technology1.
1) Hamsaraj karanath et.al. Industrially feasible alternate approaches in the manufacture of solid dispersions: A Technical Report AAPS PharmasciTech 2006; 7(4) article 87.