The equilibrium solubility of cinnarizine, pentoxifylline, and piracetam in supercritical carbon dioxide (SCCO2) were experimentally measured using a semi-flow apparatus. These compounds are active pharmaceutical ingredients (APIs) that are applied as circulatory improvers. Solid solubility data for three binary mixtures of CO2 with each API were determined at three isotherms of 308.15,318.15 and 328.15 K. The experimental pressure range was from 12 to 24 MPa. The solubility of cinnarizine in SCCO2 is from 0.29 x 10(-5) to 2.05 x 10(-4) mole fraction in this pressure range. The solubilities of pentoxifylline and piracetam are from 0.3 x 10(-4) to 1.37 x 10(-3), and from 0.75 x 10(-5) to 3.73 x 10(-5) mole fraction, respectively. We applied three semi-empirical models presented by Mendez-Santiago and Teja, Chrastil, and Bartle to correlate our measured solubility data. The average absolute relative deviation (AARD) in solid solubility correlation is from 5 to 7% using these models. Our measured data satisfied the self-consistency tests. The optimally fitted model parameters as well as the crossover region results for each binary mixture are reported. (C) 2014 Elsevier B.V. All rights reserved.