Dissolution and thermodynamic study of lamotrigine in propylene glycol+1-propanol mixtures

The solubility of lamotrigine (LTG) was investigated in non-aqueous mixed solvents of propylene glycol (PG) and 1-propanol by a shake-flask technique in the temperatures of 293.2-313.2 K. The obtained experimental data were correlated by five cosolvency mathematical models include the van't Hoff, the Jouyban-Acree, the Jouyban-Acree-van't Hoff, the mixture response surface and the modified Wilson models, and reliability of the models was checked. Furthermore, the apparent standard Gibbs energy, enthalpy and entropy of dissolution of LTG in the studied mixtures were computed using van't Hoff and Gibbs equations at mean harmonic temperature. The solubility of LTG increases with increasing the amount of PG, and maximum solubility was reached in PG mass fraction of 0.7 at 313.2 K. The experimental results were correlated by the above mentioned models, and mean relative deviations (%) for the computed data were reported to be less than 5.0.