Experimental and modeling of solubility of sitagliptin phosphate , in supercritical carbon dioxide: proposing a new association model

The solubility of an anti-hyperglycemic agent drug, (R)-4-oxo-4-[3-(trifluoromethyl)-5,6-dihydro [1,2,4] triazolo[4,3-a] pyrazin-7(8H)-yl]-1-(2,4,5-trifluorophenyl) butan-2-amine (also known as Sitagliptin phosphate ) in supercritical carbon dioxide (scCO 2 ) was determined by ananalytical and dynamic technique at different temperatures (308, 318, 328 and 338 K) and pressure (12–30 MPa) values. The measured solubilities were in the range of 3.02 × 10 –5 to 5.17 × 10 –5 , 2.71 × 10 –5 to 5.83 × 10 –5 , 2.39 × 10 –5 to 6.51 × 10 –5 and 2.07 × 10 –5 to 6.98 × 10 −5 in mole fraction at (308, 318, 328 and 338) K, respectively. The solubility data were correlated with existing density models and with a new association model.