Conventional jet nebulizers have been shown to be inefficient at generating drug-carrying droplets from aqueous suspensions. Aerosol delivery of two different aqueous suspensions was compared using a jet nebulizer and a device incorporating micropump technology, a design which may result in a more efficient production of suspension products.
Particle drug and radioactivity content of two aqueous suspensions were characterized using the Andersen II cascade impactor (28.3 lpm), measuring mass median aerodynamic diameter (MMAD), geometric standard deviation (GSD) and fine particle fraction (FPF; %<4.7 microns)). Two suspensions were compared - 99mTc-labeled human serum albumin microaggregates (MIA) produced in saline by the thermal denaturation and ultrasonication of 25% human serum albumin, and budesonide (BUD; Pulmicort Respules (0.5 mg/ml) AstraZeneca, CAN). The former was developed as a radioactive surrogate of BUD. Each suspension was delivered from the Aerodose 5.7 (AD5.7; Aerogen Inc., California), a liquid inhaler incorporating electronic micropump technology, and the LC Star (LCS; Pari GmbH, GER), a breath-enhanced conventional jet nebulizer operated with compressed O2 at 8 lpm.
Compared to the LCS, the MMAD of MIA and BUD particles delivered from the AD5.7 were significantly smaller with a significantly greater GSD. For BUD only, the FPF was significantly greater from the AD5.7. The size characteristics of the MIA particles and BUD from the AD5.7 appear to be similar.
Aerosols generated from two different aqueous suspensions using electronic micropump technology have a significantly smaller MMAD compared to a conventional jet nebulizer. Electronic micropump technology also generates a more heterodisperse suspension aerosol with a significantly greater % of steroid particles in the respirable range.
There is potential for a greater fine particle dose to be delivered more distally in the lung when using electronic micropump technology compared to conventional jet nebulizers. N=9 Mean (SD)BUD99mTc-MIAADLCSPADLCSPMMAD2.38 (0.16)3.54 (0.26)<0.0012.15 (0.28)2.96 (0.28)<0.001GSD2.21 (0.33)1.97 (0.49)0.0122.51 (0.28)1.73 (0.11)<0.001FPF (%)81.61 (4.61)69.12 (3.68)<0.00180.08 (1.88)79.99 (2.03)0.926
M.B. Dolovich, Aerogen Inc.