ABSTRACT
The concept of solubility is important to a pharmacist not only because it governs the preparation of solutions as a dosage form but also because a drug must be in solution before it can be absorbed by the body to exert biological activity. The concentration of a drug or other substance in solution can be expressed in many different ways. The driving force in dissolution is mainly the interaction of the solvent molecules with solute molecules or the solute ions. The initial step in dissolution is the work required to separate solute particles and is dependent on intermolecular forces of the solute. The thermodynamic theories of solution and solubility are based on ideal solutions. Unfortunately, not many solutions behave ideally, but rather are referred to as nonideal solutions, or real solutions, where the interactions between solute and solute, solute and solvent, and solvent and solvent molecules differ.
