The nurse is explaining the differences between uncontrolled and controlled substances.
Which of the following medications is a controlled substance?

Choice A rationale

Beclomethasone (QVAR) is an inhaled corticosteroid used for long-term prophylaxis of asthma. It works by reducing inflammation in the airways, preventing asthma attacks and improving lung function.

Choice B rationale

Metoprolol is a beta-adrenergic blocker used for treating hypertension and certain heart conditions. It is not used for asthma management.

Choice C rationale

Phenytoin is an antiepileptic medication used to control seizures. It does not have a role in asthma management.

Choice D rationale

Furosemide is a loop diuretic used to treat conditions like edema and hypertension by promoting the excretion of excess fluid. It is not indicated for asthma management.

Choice A rationale

Spironolactone is a potassium-sparing diuretic that acts on the collecting ducts and late distal tubules but not on the loop of Henle.

Choice B rationale

Hydrochlorothiazide is a thiazide diuretic that works on the distal convoluted tubule, not the loop of Henle.

Choice C rationale

Furosemide is a loop diuretic that acts on the ascending limb of the loop of Henle to inhibit sodium and chloride reabsorption, leading to increased urine output.

Choice D rationale

Mannitol is an osmotic diuretic that primarily acts on the proximal tubule and the descending limb of the loop of Henle.