Laboratory Study Comparing Pharmacopeial Testing of Nebulizers with Evaluation Based on Nephele Mixing Inlet...

Area of Science:

• Pharmaceutical Technology
• Inhalation Drug Delivery
• Respiratory Medicine

Background:

• Accurate determination of fine droplet dose (FDD) is crucial for predicting lung deposition and in vivo responses from nebulized preparations.
• Current compendial methods (USP, EP) involve separate determination of delivered dose (DD) and fine droplet fraction (FDF), then calculating FDD.
• These compendial methods may not accurately reflect the dynamic airflow during patient inhalation.

Purpose of the Study:

• To investigate the feasibility of the mixing inlet lung simulation (MILS) approach for direct determination of FDD.
• To compare FDD measurements obtained by MILS with the traditional compendial method.
• To assess if the MILS approach provides a more clinically relevant measure of lung deposition.

Main Methods:

• Developed and utilized the Nephele mixing inlet to allow cascade impactor analysis under simulated breathing patterns.
• Tested vibrating membrane nebulizers (eFlow® Rapid) with aqueous salbutamol sulfate under simulated adult tidal breathing.
• Determined FDD<5μm using both the MILS approach and the compendial 'combination' method for comparison.

Main Results:

• The MILS approach yielded FDD<5μm values that were 72% of those obtained by the compendial method.
• The MILS methodology integrates nebulizer performance with a realistic, continuously varying inspiratory flow profile.
• The discrepancy suggests the compendial method may overestimate the actual dose delivered to the lungs.

Conclusions:

• The MILS approach is feasible for directly determining FDD<5μm from nebulizers.
• MILS provides a more accurate assessment of lung-deposited dose compared to the current compendial method.
• The findings infer that the standard compendial method likely overestimates the dose reaching the human lung.