Which excretion route involves expelling drug via the lungs?

Which excretion route involves expelling drug via the lungs?

• A. Exhalation (pulmonary)
• B. Urine (renal)
• C. Stool (hepatic, biliary)
• D. Sweat

Answer: (A)

Exhalation of a drug occurs when the substance is volatile enough to move from the blood into the alveoli and be breathed out unchanged. This pulmonary route is the primary elimination path for volatile compounds, such as volatile anesthetics, and for drugs with low blood solubility that readily transfer to the air in the lungs. The rate of this excretion depends on how volatile the drug is and on the amount of ventilation—the more rapid the breathing, the faster the drug is eliminated through the lungs. In contrast, many drugs are eliminated mainly by the kidneys into the urine after being metabolized or conjugated, or by the liver into the bile and then into the stool. Sweat is a minor route that can contribute to excretion for some substances but is not the main pathway for most drugs. Therefore, expelling a drug via the lungs is best described as exhalation (pulmonary).

Exhalation of a drug occurs when the substance is volatile enough to move from the blood into the alveoli and be breathed out unchanged. This pulmonary route is the primary elimination path for volatile compounds, such as volatile anesthetics, and for drugs with low blood solubility that readily transfer to the air in the lungs. The rate of this excretion depends on how volatile the drug is and on the amount of ventilation—the more rapid the breathing, the faster the drug is eliminated through the lungs.

In contrast, many drugs are eliminated mainly by the kidneys into the urine after being metabolized or conjugated, or by the liver into the bile and then into the stool. Sweat is a minor route that can contribute to excretion for some substances but is not the main pathway for most drugs.

Therefore, expelling a drug via the lungs is best described as exhalation (pulmonary).