The accurate solubility of salbutamol sulfate, budesonide, and formoterol fumarate dihydrate in hydrofluoroalkane propellant 134a at 25 degrees C for 24 h, are reported. The authors describe a novel reusable in-line pressurized solubility apparatus containing an integral filter holder and a continuous decrimpable valve for the determination of drug/excipients solubility in pressurized metered dose inhalers. The solubility was determined by high-performance liquid chromatography. Solubility of salbutamol sulfate was determined as being below the detection limits while budesonide and formoterol fumarate dihydrate solubility were 23.136 +/- 2.951 mu g. g(-1) and 0.776 +/- 1.023 mu g. g(-1), respectively (n = 3). This novel solubility apparatus offers an improved ease of use and potential higher analytical throughput.
Traini, D., Young, P. M., Price, R., & Rogueda, P. (2006). A novel apparatus for the determination of solubility in pressurized metered dose inhalers. Drug Development and Industrial Pharmacy, 32 Nov-Dec(10), 1159-1163. https://doi.org/10.1080/03639040600920325