Basic Concepts and Requirements of Galenic Formulations

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2. Formulation for Clinical Studies

2.2. Solution for poorly soluble medicines

Polymers in medicines formulation are also applied within dosage forms for active substances whose crystals are only slightly soluble in water. Without special processing, such active substances would be excreted by the body unchanged without having any effect. Modern techniques make it possible to embed active substances in water-soluble polymers. In this process the insoluble crystals are split up, and the molecules become  'amorphous' (or shapeless) without a fixed structure. The researchers can now keep the molecules amorphous with the help of polymers. This 'solid solution' of active ingredient and polymer will more easily dissolve in water (and digestive fluids) than the crystals of active substance alone. In many cases, this also leads to a temporary increase in the concentration of dissolved active substance molecules. They can now be absorbed from the intestine into the bloodstream.