A patient with major depressive disorder is prescribed fluoxetine 40 mg PO daily. The pharmacy provides fluoxetine liquid with a concentration of 20 mg/5 mL. How many mL should the nurse administer?

Choice A reason: 5 mL contains only 20 mg, which is half the prescribed dose. Administering this amount would underdose the patient. Choice B reason: 20 mL contains 80 mg, which is double the prescribed dose. This would risk toxicity and adverse effects. Choice C reason: 15 mL contains 60 mg, which exceeds the prescribed dose by 20 mg. This would also risk overdose. Choice D reason: 10 mL contains exactly 40 mg, matching the prescribed dose. This ensures safe and effective administration. Step 1: Ordered dose = 40 mg. Step 2: Concentration = 20 mg per 5 mL. Step 3: (40 mg ÷ 20 mg) = 2. Step 4: 2 × 5 mL = 10 mL. Result = 10 mL.