Dissolution Enhancement of Poorly Soluble Drugs

Keywords: Poorly soluble drug, dissolution rate

Due to drug's poor solubility they have few disadvantages like increased dosage, short interval between two subsequent administration, increased side effects and last but not list is its dissolution.

But as technology get smarter and smarter, industry develop more and more suitable technology to compete against this problem. Various pharmaceutical approaches found in this area. Some of them are discussed here.

Lipid based formulations
These formulations include lipid solutions, lipid emulsion, micro emulsion and Self Dispensing Lipid Formulations. (SDLF). Lipid increases the solubility of drugs. Lipid solutions consist of drug dissolved in vegetable oil or medium chain triglycerides. Lipid emulsion and SDLF have a mixture of lipid and surfactant. Generally such formulations are used for the oral solutions. Due to high amount of lipids, they facilitate the drug to absorb directly in systemic circulation so this formulation is being prevented from first pass metabolism.

Porous microparticle technology
Poorly soluble drug is entrapped in microparticle having a porous, water soluble, sponge like matrix. When mixed with water, the matrix dissolves, wetting the drug and leaving a suspension of rapidly dissolving drug particles. This technology applied as Hydrophilic Drug delivery System (HDDS) ™.

Functional Polymer Technology
Polymers enhance the dissolution rate of poorly soluble drugs by avoiding the lattice energy of the drug crystal, which is the main barrier of rapid dissolution in aqueous media. Polymer in nature are made up of ion-exchangeable materials which have either basic or acidic groups that interact with surrounding medium and exchange their ions with surrounding environment. This final complex knows as Resinate. This complex can be formulated as a suspension, dry powder or tablet.

Controlled Precipitation technology
In this process, the drug is dissolved in a water miscible organic solvent and then dispersed into aqueous medium containing stabilizers (HLPC, Cellulose ethers and gelatin). Stabilizers control particles size and enhance the dissolution rate of poorly soluble drug.

Size Reduction Technology
This technique is used to increase the dissolution rate of poorly soluble drugs due to the enormous surface that is generated. The drug particles are reduced to microns or nano-size by nano sizing, precipitation, cryogenic and supercritical fluid technologies.
Solid Dispersion Method
In which drug is dispersed in a carrier to make it amorphous. To enhance the preparation of solid dispersion various approaches are includes solvent evaporation, fusion, spray drying and lyophilization.

Conclusion

As to stand in the competition of the drug market, newer molecules are being researched and introduced in market but some of them are soluble, few are slightly soluble. Some of them are poorly soluble drugs. So to increase the market availability of new drugs which have such properties, will force companies and laboratory to develop new strategies and technologies.