*3.8. Solubility and Dissolution*

Drug solubility occurs under a dynamic equilibrium state, which determines the maximum concentration in a saturated solution when excess solid is present in the media. The dissolution rate is a kinetic process that measures the drug concentration, which passes into the media with respect to time. These two parameters are determined by the solvation of the molecular components and the strength of the crystal structure lattice [47]. To improve the drug solubility, the solvent affinity must be increased and/or lower the lattice energy. These can be altered via cocrystal formation, although it is also influenced by the coformer solubility [48]. Since the aqueous solubility values pyridinecarboxyamides are greater than those of **D, L-H2ma**, the presence of coformers may appear to improve the dissolution profile of mandelic acid (Figure 15).

**Figure 15.** Solubility values in water (mg mL<sup>−</sup>1) of the coformers and cocrystals **1**–**3**.
