A nurse is preparing to administer lithium carbonate 450 mg to a patient diagnosed with bipolar disorder. The available medication is lithium carbonate 300 mg tablets. How many tablets should the nurse administer?

Choice A reason: One tablet equals 300 mg, which is insufficient to meet the prescribed 450 mg dose. Administering only one tablet would underdose the patient, reducing therapeutic effectiveness. Choice B reason: Three tablets equal 900 mg, which is double the prescribed dose. This would cause toxicity and serious adverse effects, making it unsafe. Choice C reason: Two tablets equal 600 mg, which exceeds the prescribed dose by 150 mg. This would risk lithium toxicity, including tremors, confusion, and renal impairment. Choice D reason: 1.5 tablets equal exactly 450 mg, which matches the prescribed dose. This ensures therapeutic effectiveness while maintaining safety. Step 1: Available tablet strength = 300 mg. Step 2: Ordered dose = 450 mg. Step 3: (450 mg ÷ 300 mg) = 1.5 tablets. Result = 1.5 tablets.