In this work, drug-loaded polymer microparticles were prepared by a supercritical solution impregnation (SSI) process with nitrendipine as the model drug and PLLA–PEG–PLLA as the drug carrier.

Curcumin is a natural phenolic pigment extracted from turmeric and has a good pharmacological activity in anti-inflammatory, antioxidant, hypolipidemic, and antitumor. It has been frequently used in drug-loaded microspheres recently. However, the reports on its solubility in supercritical fluids have not been seen yet. In the present study, solubility of curcumin in the supercritical carbon dioxide (ScCO 2 ) was determined using the dynamic equilibrium method. The experimental measurements were performed at temperatures of 35, 45, and 55 °C and pressure range from 8 to 20 MPa. The measured data showed that the solubilities of curcumin were between 1.82 × 10 −8 and 1.97 × 10 −6 (mole fractin) for the corresponding temperatures and pressures. The effects of temperature, pressure, and with and without ethanol cosolvent on the solubility were investigated. The measured solubilities were calculated and correlated by semi-empirical formulas Chrastil and Mendez-Santiago and Teja models. The results showed that the experimental values of solubility were in good agreement with the theoretical ones, and the average absolute relative deviations (AARD) were 5.88% and 11.68% without cosolvent, and the AARD of the latter was 15.50% with the ethanol cosolvent.

No abstract

The solubility of a drug in supercritical carbon dioxide (ScCO2) is an important parameter for preparing the controlled release drug by supercritical fluid technology. In this work, a test technique of the flowing solubility is developed, and the test apparatus is set up based on an improved dynamic method. The solubility of 5-fluorouracil (5-Fu) in ScCO2 with or without the cosolvent of ethanol is measured. The effects of the operating parameters including the pressure, the temperature, and the concentration of cosolvent on the solubility of 5-Fu in ScCO2 are investigated experimentally. The obtained solubility data are correlated by Chrastil and Mendez-Santiago and Teja models. The average absolute relative deviation (AARD) of the calculated value with the experimental ones is 3.52 % by the Chrastil model without cosolvent, and it is 14.6 % by the Mendez-Santiago and Teja model with cosolvent of ethanol. The results show that the addition of the ethanol as a cosolvent could significantly increase the solubility of 5-Fu in ScCO2. In addition, the partition coefficients K of 5-Fu between ScCO2 and poly(l-lactic acid) (PLLA) are determined experimentally and correlated by Banchero’s empirical equation. The results show that the partition coefficient decreases with the increase of the pressure and increases with the increase of temperature. The calculated value of the partition coefficient K is well consonant with the experimental data, and the AARD is 14.7 %.