Which method of drug delivery is less effective in reaching the lower lungs?

Oral ingestion is less effective in reaching the lower lungs because when a medication is taken orally, it must first be absorbed through the gastrointestinal tract before entering the bloodstream. This pathway does not deliver the drug directly to the respiratory system. Although systemic absorption can occur, the medication's effects on the lungs are indirect and typically much less targeted compared to other inhalation methods.

In contrast, methods like nebulization, dry powder inhalation, and metered-dose inhalation deliver medications directly to the respiratory tract, allowing for a more immediate and effective impact on the lower lungs. These techniques create an aerosolized form of the medication that can penetrate deeper into the lung tissues, making them preferable for treating respiratory conditions.