3.1.5. Solubility of Drug

In contrast to being poorly soluble in water, PRX readily dissolves in methanol, ethanol, and dichloromethane, among other organic solvents. PRX solubility was investigated in a variety of solvents including water, PBS pH 7.4, and methanol. The investigation shows

that the drug was freely soluble in methanol, soluble in PBS pH 7.4, and very slightly soluble in water (Table 4).

**Sr. No. Solvent Reference Solubility (mg/mL) Observed Solubility (mg/mL)** 1 Methanol 5.0 4.44 2 PBS pH 7.4 0.592 0.6606

3 Water 0.0076 0.0066

**Figure 1.** UV spectra depicting λmax of PRX in methanol (**A**), methanolic HCl (**B**), PBS pH 6.8 (**C**) and PBS pH 7.4 (**D**).
