Solubility of buprenorphine hydrochloride in supercritical carbon dioxide: Study on experimental measuring and thermodynamic modeling

Abstract

Nowadays, supercritical fluids (SCFs) technologies present a processing option for obtaining new products with noteworthy characteristics. Access to reliable solubility data of pharmaceutical compounds in SCFs is considered as the first step for recrystallizing, separating, and producing nano particles via processes based on this type of technique. In this study, high-pressure solubility of buprenorphine hydrochloride, a strong pain reliever, in supercritical carbon dioxide (scCO2) was measured at temperature and pressure conditions of 308–338 K and 120–270 bar, for the first time. The minimum and maximum solubility values, in terms of equilibrium mole fractions, were found to be 0.131 × 10-4 (at 338 K and 120 bar) and 4.752 × 10-4 (at 338 K and 270 bar), respectively. Thereafter, the obtained data were correlated using two different approaches, namely Peng-Robinson (PR) equation of state (EoS) and a set of semi-empirical models. Results from applying statistical criteria indicated that Jouyban and Sodeifian models are suitable choices for predicting solubility data. Furthermore, using the obtained correlation results, the total and vaporization enthalpies of buprenorphine hydrochloride dissolution in scCO2 were estimated to be 65.59 and 85.60 kJ/mole, respectively.