Solubility Research Paper

Solubility is the ability of a substance, or solute, to dissolve and homogenously disperse throughout another substance, or solvent. In order for drugs to be therapeutically effective and bioavailable, it must first be highly soluble. Poor solubility and low dissolution rates of drugs in the aqueous gastrointestinal tract lead to decreased bioavailability. Solubilization of poorly soluble drugs is a challenge in the formulation of newly developed drugs. Because many medications are administered orally and therefore must be easily absorbed, the solubility of these drugs must be enhanced. Some of the techniques used to increase solubility are through the utilization of salts, by employing micelle formation techniques, and through use of complexation
A hydrotrope is an ionic organic salt compound consisting of an alkali metal salt of an organic acid which has the ability to make hydrophobic compounds more soluble. This is termed the hydrotropic effect. Examples of hydrotropic salts include ETH maleate, succinate, and oxalate2. The hydrotropic effect is achieved by adding an organic salt which will increase the saturation solubility of a drug in an aqueous solution by increasing hydrogen bonding. The mechanism of hydrotropism involves weak interactions between the hydrotropic agent and the insoluble drug. This method closely resembles complexation. Commonly used hydrotropic substances include caffeine, sorbitol, urea, nicotinamide, and sodium benzoate. Because hydrotropic substances consist of a hydrophobic end as well as a hydrophilic end, when these substances are added to a solute, the resulting effect is an increase in the water solubility of poorly soluble drugs by joining the hydrophobic end of the hydrotrope with the hydrophobic drug via weak interactions. The hydrophobic ends of the hydrotrope weakly bind with the hydrophobic drug, thus only exposing the hydrophilic end to the water
Using micellar solubilization can allow the drug to stay in the circulatory system for longer periods and, because of their larger size, they can amass in areas with leaky vasculature. Besides increasing solubility, another advantage of micellization is reduced risk of toxicity and enhanced permeability. An interesting feature of micelles is the fact that the location of the drug in the micelle depends on the degree of hydrophobicity of the drug. The more hydrophobic or poorly soluble a drug is, the closer to the interior of the micelle it is located, while less hydrophobic drugs are found closer to the exterior of the