Loxoprofen Solubility in Supercritical Carbon Dioxide: Experimental and Modeling Approaches
Samyar Zabihi, Seyyed Hamid Esmaeili-Faraj, Fatemeh Borousan, Ali Zeinolabedini Hezave, Saeed Shirazian
Abstract
The solubility of loxoprofen as a nonsteroidal anti-inflammatory drug (NSAID) is measured at various temperatures (308, 318, 328, and 338 K) and pressures (12, 16, 20, 24, 28, 32, 36, and 40 MPa) in supercritical carbon dioxide (SC-CO2). The solubility data were measured using a gravimetric-based approach and revealed the solubility range of 1.35 × 10–5 to 1.28 × 10–3 based on the mole fraction of loxoprofen. The results revealed that solubility can be significantly enhanced from 1.04 × 10–5 to 1.28 × 10–3 (mole fraction basis) for the isotherm at 338 K because of the effect of temperature which can boost the pressure effect on solubility enhancement, at pressures greater than crossover (around 20 MPa for the case of loxoprofen). Moreover, the experimental data points were modeled using five different density-based correlations including Chrastil, Garlapati and Madras, Mendez-Santiago and Teja (MST), Bartle et al., and Kumar and Johnston (K–J) models because measuring the solubility of loxoprofen in entire required ranges of pressure and temperature is impossible or expensive similar to the other pharmaceuticals. The results of modeling revealed that one can correlate the loxoprofen solubility data with an accuracy of about 9.2% (Mendez-Santiago–Teja), 10.7% (Bartle et al.), 7.1% (Kumar and Johnstone), 12.7% (Chrastil), and 12.7% (Garlapati and Madras) based on average absolute relative deviation percent (AARD %).