Solubility Determination and Modeling for Tirofiban in Several Mixed Solvents at 278.15–323.15 K

During the determination of the solubility of tirofiban, pure methanol, ethanol, isopropanol, and ethylene glycol (EG) play a major role in dissolution; then, water is added in sequence for dilution to obtain a dispersion system with different composition structures, and the concentration gradient between each mixed liquid is 0.1 (mass fraction). The drug tirofiban whose solubility is to be tested is added to it, using the isothermal method, with a high temperature of 323.15 K as the starting point and an interval of 5 K to a low temperature of 278.15 K. The pressure conditions do not require special requirements at ordinary atmospheric pressure environment (101.1 kPa). Results show that when the temperature approaches the high level, more drugs can be dissolved in the same amount of solvent. Conversely, when the temperature is close to the low level, the drug is more difficult to dissolve. The temperature constant, the proportion of organic solvent is large, the dissolving capacity of the dispersion system will develop in a positive direction. Conversely, if the proportion of water is large, the dissolving power will decrease. Tirofiban crystals accepted the determination of various dissolution data, including those of the undissolved raw materials that have undergone X-ray power diffraction (XPRD) detection. The results obtained are encouraging, no change in the crystal structure of the substance is found. Three models, Jouyban–Acree model, van’t Hoff–Jouyban–Acree model, and modified Apelblat–Jouyban–Acree model, were employed to calculate the experimental tirofiban solubility, and the relative average deviation (RAD) and the root-mean-square deviation (RMSD) were not higher than 1.18% and 4.0 × 10^–6. The research on tirofiban is not only a simple measurement of the dissolution data but more importantly, with the support of these data, more thermodynamic data can be calculated to obtain tirofiban, which is an indispensable link between the improvement of the production process of tirofiban and the synthesis of pharmaceutical preparations.