Solubilities of chlormezanone, metaxalone and methocarbamol in supercritical carbon dioxide

• The novel solubility data of three skeletal muscle relaxants in SCCO2 are reported.
• The measures T and P ranges are 308.2–328.2 K and 12–24 MPa, respectively.
• The experimental data satisfy the self-consistency test.
• The solubility data were satisfactorily correlated by three semi-empirical models.
• The crossover region data for three binary mixtures are reported.

The solubilities of three active pharmaceutical ingredients (APIs) in supercritical carbon dioxide were measured in this study using a semi-flow apparatus. These APIs are chlormezanone (C11H12ClNO3S), metaxalone (C12H15NO3) and methocarbamol (C11H15NO5) that are all used as skeletal muscle relaxants. The solubility data are reported for three isotherms at 308.2, 318.2 and 328.2 K, with the pressure range from 12 to 24 MPa. Most solubility data are within the range of 10−6 to 10−4 mole fraction for each API. The crossover phenomena were observed from the experimental results for all three systems. These solubility data satisfied the thermodynamic consistency tests. They were then correlated using three semi-empirical models. With the optimally fitted binary interaction parameters, satisfactory correlation agreement is presented for each binary mixture.

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