Williams R O, Repka M, Liu J
College of Pharmacy, University of Texas at Austin, Texas 78712-1074, USA.
Drug Dev Ind Pharm. 1998 Aug;24(8):763-70. doi: 10.3109/03639049809082724.
Hydrofluoroalkanes (HFAs) are used to replace chlorofluorocarbons (CFCs) as non-ozone-depleting propellants for pressurized metered-dose inhalers (pMDIs). HFA 134a and HFA 227 are used in combination to precisely manipulate the density and vapor pressure of pMDI formulations. The influence of propellant composition on the dose delivery characteristics of a suspension-based pMDI formulation was investigated. The results showed that as the density of the propellant blends approached the density of the suspended drug particles, the formulation became more physically stable and exhibited the most consistent dose delivery and greatest respirable fraction. The mass median aerodynamic diameter of the aerosolized particles contained in the emitted dose also was decreased by using propellant blends with higher vapor pressures. The performance of a suspension-based pMDI formulation was optimized by varying the propellant composition using HFA 134a and HFA 227.
氢氟烷烃（HFAs）被用作氯氟烃（CFCs）的替代品，作为压力定量吸入器（pMDIs）的无臭氧消耗推进剂。HFA 134a和HFA 227联合使用，以精确控制pMDI制剂的密度和蒸气压。研究了推进剂组成对混悬型pMDI制剂剂量递送特性的影响。结果表明，随着推进剂混合物的密度接近混悬药物颗粒的密度，制剂在物理上变得更稳定，表现出最一致的剂量递送和最大的可吸入部分。通过使用具有较高蒸气压的推进剂混合物，发射剂量中雾化颗粒的质量中值空气动力学直径也减小了。通过使用HFA 134a和HFA 227改变推进剂组成，优化了混悬型pMDI制剂的性能。
