Evaluation of nebulizer performance under various humidity conditions

Area of Science:

• Respiratory medicine
• Pharmaceutical sciences
• Biomedical engineering

Background:

• Jet nebulizers are critical for delivering respiratory medications.
• Aerosol droplet evaporation, influenced by relative humidity (RH), affects drug delivery.
• Understanding RH impact is crucial for optimizing nebulizer therapy.

Purpose of the Study:

• To evaluate how relative humidity (RH) affects aerosol characteristics and drug delivery from four jet nebulizers.
• To compare albuterol (solution) and budesonide (suspension) formulations under varying RH conditions.
• To assess particle distribution, nebulizer efficiency, and dead volume at 5%, 50%, and 80% RH.

Main Methods:

• Four jet nebulizers (PARI LC Plus, SideStream, VixOne, Micromist) were tested.
• Albuterol and budesonide formulations were used.
• Measurements included mass median aerodynamic diameter (MMAD), geometric standard deviation (GSD), nebulizer efficiency (respirable fraction), and dead volume at different RH levels.

Main Results:

• Increased RH generally led to larger MMAD, except for VixOne with albuterol.
• Budesonide suspensions consistently showed higher MMAD than albuterol solutions.
• Respirable fraction (inhalation dose) decreased with higher RH, with notable reductions (15-27%) from 5% to 50% RH for most devices.
• PARI LC Plus exhibited lower dead volume at 5% RH due to its design.

Conclusions:

• Relative humidity significantly impacts jet nebulizer performance, affecting aerosol particle size and inhaled drug dosage.
• Therapeutic efficacy may be compromised in dry or humid environments due to altered aerosol properties.
• Nebulizer design and drug formulation interact with RH, influencing drug delivery efficiency.