What parameter reflects the proportion of emitted dose that actually deposits in the lungs?

What parameter reflects the proportion of emitted dose that actually deposits in the lungs?

• A. Total emitted dose
• B. Systemic absorption rate
• C. Inhalation flow rate
• D. Lung deposition fraction or lung dose efficiency

Answer: (D)

Understanding how much of what you emit from the inhaler actually reaches the lungs hinges on the lung deposition fraction. This parameter is the portion of the emitted dose that ends up depositing in the lungs, rather than being exhaled or depositing in the mouth–throat. If an inhaler releases 100 units and 30 of those units deposit in the lungs, the lung deposition fraction is 0.30 (30%). This measure directly expresses the efficiency of delivering the drug to the lungs. Why the others don’t fit as well: total emitted dose is simply how much leaves the device, not how much actually deposits in the lungs. Systemic absorption rate describes how much drug enters the bloodstream after deposition, not the fraction that deposits in the lungs. Inhalation flow rate affects how the air and particles move during inhalation and can influence where particles deposit, but it is not the measure of the proportion that deposits in the lungs itself.

Understanding how much of what you emit from the inhaler actually reaches the lungs hinges on the lung deposition fraction. This parameter is the portion of the emitted dose that ends up depositing in the lungs, rather than being exhaled or depositing in the mouth–throat.

If an inhaler releases 100 units and 30 of those units deposit in the lungs, the lung deposition fraction is 0.30 (30%). This measure directly expresses the efficiency of delivering the drug to the lungs.

Why the others don’t fit as well: total emitted dose is simply how much leaves the device, not how much actually deposits in the lungs. Systemic absorption rate describes how much drug enters the bloodstream after deposition, not the fraction that deposits in the lungs. Inhalation flow rate affects how the air and particles move during inhalation and can influence where particles deposit, but it is not the measure of the proportion that deposits in the lungs itself.