Radiolabeling Method for Lyophilizate for Dry Powder Inhalation Formulations

Area of Science:

• Pharmaceutical Sciences
• Radiochemistry
• Drug Delivery

Background:

• Human lung deposition data is crucial for orally inhaled drug product development.
• Radionuclide imaging is a key method for quantifying lung deposition.
• Existing radiolabeling methods like TechneCoat are unsuitable for lyophilized dry powder inhalation (LDPI) formulations.

Purpose of the Study:

• To develop and validate a novel radiolabeling method for LDPI formulations.
• To enable accurate quantification of drug deposition in the human lung.

Main Methods:

• Modification of the TechneCoat apparatus to prevent aerosolization of the lyophilized cake.
• Radiolabeling of interferon alpha (IFN) model LDPI formulations with Technetium-99m (^99mTc).
• Validation using aerodynamic particle size distribution measurements.

Main Results:

• The modified TechneCoat method successfully radiolabeled LDPI formulations without aerosolization.
• ^99mTc-labeled IFN LDPI formulations exhibited similar aerodynamic particle size distribution compared to unlabeled formulations (within ±15% difference).
• The developed method is suitable for characterizing LDPI formulations.

Conclusions:

• A modified TechneCoat apparatus provides a viable method for radiolabeling LDPI formulations.
• This technique supports the quantification of drug deposition in human lungs.
• The method is valuable for the development of orally inhaled drug products.