A liquid medication for depression needs to be administered at 20 mg every 6 hours. The medication available is 10 mg/mL. How many milliliters should be administered for each dose?

Choice A reason: Administering 5 mL would result in a total dosage of 50 mg per administration, which significantly exceeds the prescribed 20 mg. This calculation error could lead to severe medication toxicity or increased side effects, violating the basic safety protocols of medication administration and pharmacological standards. Choice B reason: A 3 mL dose provides 30 mg of the medication. This is a 50% overdose compared to the ordered 20 mg. In clinical practice, precision in liquid measurements is vital to maintain therapeutic windows and prevent adverse drug reactions associated with incorrect dosing of antidepressants. Choice C reason: To calculate the dose, the formula is Dose Ordered / Dose on Hand x Volume = Amount to Administer. Therefore, 20 mg / 10 mg x 1 mL = 2 mL. This ensures the patient receives the exact 20 mg required every 6 hours to maintain steady-state plasma concentrations. Choice D reason: A 1 mL dose provides only 10 mg, which is half of the therapeutic amount ordered by the provider. Sub-therapeutic dosing can lead to treatment failure, prolongation of depressive symptoms, and potential exacerbation of the underlying psychiatric condition due to inadequate neurotransmitter modulation.