Solubility is a thermodynamic process which determines “how much” of the solute dissolves in a solvent, whereas dissolution is a kinetic process which determines “how long” it takes to reach the value. Both these processes are important in determining the residence time of an inhaled drug locally in the lungs. Equilibrium solubilities of moxifloxacin and ethionamide were determined in PBS, pH 7.4 without and with lung surfactant, Curosurf®. Solubilities of moxifloxacin and ethionamide (Table 1) in PBS were found to be 17.68 ± 0.85 mg/mL and 0.46 ± 0.02 mg/mL while in 0.4% curosurf were found to be 20.76 ± 0.35 mg/mL and 0.56 ± 0.03 mg/mL, respectively. Solubility of moxifloxacin was ~38 time higher than ethionamide in both the media tested. The addition of lung surfactant (0.4% curosurf) has significantly (p>0.05) increased the solubility of both the drugs. …show more content…
However, the addition of surfactant increased the wettability of the drug, easily dispersed in the medium and showed increased solubility similar to the previous reports (10, 12, 29,