Soluble drugs, poorly solubilization systems

Emulsions are either oil phase dispersed in water phase, an oil-in-water (o/w) emulsion, or water phase dispersed in oil phase, a water-in-oil (w/o) emulsion. If a poorly water-soluble drug substance is soluble in oil, it can be solubilized in an emulsion where it partitions into the oil phase. The total solubility in an emulsions, is the summation of concentrations in the aqueous and oil phases (Strickley, 2004). The total solubility of the emulsion system is the sum of the drug concentration in the aqueous phaseSv, and the concentration in the oil phase, which can be approximated by the product of the drug s solubility in the pure oi i, multiplied by the fraction of the oil in the emulsion ... 

Rubino et al. [64-66] studied solubilization by cosolvents in binary and ternary systems. They determined that the solubility of poor water-soluble drugs was approximately described by the log-linear solubility equation as applied to multiple solvent systems ... 

In some cases, low drug solubility may make some delivery platforms better candidates than others. Application of solubilization techniques enables design and development of oral MR dosage forms for poorly water-soluble drugs and can provide more choices and options in designing such a delivery system. 

A cosolvent system essential to the solubilization of a poorly soluble drug can also serve as a potent extractant of plastic additives. 

During the last two decades, significant efforts have been made in the development of solubilization systems for poorly soluble drugs. As listed in Table 1, various methods have been explored to increase water solubilities of poorly soluble drugs. 

A preferred location of the solubilizate molecule within the micelle is largely dictated by chemical structure. However, solubilized systems are dynamic and the location of molecules within the micelle changes rapidly with time. Solubilization in surfactant aqueous systems above the critical micelle concentration offers one pathway for the formulation of poorly soluble drugs. From a quantitative point of view, the solubilization process above the CMC may be considered to involve a simple partition phenomenon between an aqueous and a micellar phase. Thus the relationship between surfactant concentration Cm and drug solubility Ctot is given by Eq. (3). 

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