The most commonly used host molecules are cyclodextrins. Current SCF processes have demonstrated the ability to create nanoparticulate suspensions of particles 5–2,000 nm in diameter. The methods like solid dispersion, complexation, liquisolid, hydrotropy, sonocrystallization, self emulsifying method, are commonly referred for solubility enhancement. Solubility equilibrium occurs when the two processes proceed at a constant rate. Solubility may be stated in units of concentration, molality, mole fraction, mole ratio, and other units [Extensive use of solubility from different perspective has led to solubility being expressed in various manners. soluble drugs. Especially for class II (low solubility and high permeability) substances according to the BCS, the bioavailability may be enhanced by increasing the solubility and dissolution rate of the drug in the gastro-intestinal fluids. Moreover, precipitation technique is not applicable to drugs, which are simultaneously poorly soluble in aqueous and nonaqueous media [The nanosuspensions are prepared by using high-shear media mills. the BCS system. Drug solubility is the maximum concentration of the drug dissolved in the solvent under specific condition of temperature, pH and pressure. The flexibility and precision offered by SCF processes allows micronisation of drug particles within narrow ranges of particle size, often to submicron levels. In this method, the suspension of a drug and surfactant is forced under pressure through a nanosized aperture valve of a high pressure homogenizer. The thermal stress which may occur during comminution and spray drying is also a concern when processing thermosensitive or unstable active compounds. One may also speak of solid solution, but rarely of solution in a gas.The extent of solubility ranges widely, from infinitely soluble (fully miscible) such as ethanol in water, to poorly soluble, such as silver chloride in water. Particle size reduction is thus permitting an efficient, reproducible, and economic means of solubility enhancement. The volume estimate of 250 mL is derived from typical bioequivalence study protocols that prescribe administration of a drug product to fasting human volunteers with a glass of water [The intestinal permeability classification is based on a comparison to the intravenous injection. The oral bioavailability depends on several factors including aqueous solubility, drug permeability, dissolution rate, first-pass metabolism, presystemic metabolism, and susceptibility to efflux mechanisms. Cryogenic inventions can be defined by the type of injection device (capillary, rotary, pneumatic, and ultrasonic nozzle), location of nozzle (above or under the liquid level), and the composition of cryogenic liquid (hydrofluoroalkanes, NBriggs and Maxvell invented the process of spray freezing onto cryogenic fluids. Solubility does not also depend on particle size or otherIUPAC defines solubility as the analytical composition of a saturated solution expressed as a proportion of a designated solute in a designated solvent. Useing traditional approaches for nearly insoluble drugs may not be able to enhance the solubility up to desired level.Micronization is another conventional technique for the particle size reduction. For orally administered drugs solubility is the most important one rate limiting parameter to achieve their desired concentration in systemic circulation for pharmacological response. The most frequent causes of low oral bioavailability are attributed to poor solubility and low permeability.Solubility also plays a major role for other dosage forms like parenteral formulations as well [More than 40% NCEs (new chemical entities) developed in pharmaceutical industry are practically insoluble in water. Surfactant also improves wetting of solids and increases the rate of disintegration of solid into finer particles [Examples of poorly soluble compounds that use Micellar solubilization are antidiabetic drugs, gliclazide, glyburide, glimepiride, glipizide, repaglinide, pioglitazone, and rosiglitazone [Hydrotrophy is a solubilisation process, whereby addition of a large amount of second solute, the hydrotropic agent results in an increase in the aqueous solubility of first solute. A drug is considered highly soluble when the highest dose strength is soluble in 250 mL or less of aqueous media over the pH range of 1 to 7.5.