A nurse is caring for a client who has schizophrenia and is experiencing hallucinations. The provider prescribes chlorpromazine 50 mg IM every 4 hr as needed. Available is chlorpromazine injection 25 mg/mL. How many mL should the nurse administer per dose? (Round the answer to the nearest whole number. Use a leading zero if it applies. Do not use a trailing zero.)

To calculate the volume to administer, use the standard dosage calculation formula: desired dose divided by the available concentration. The provider ordered 50 mg of chlorpromazine, and the available concentration is 25 mg per mL. Dividing 50 mg by 25 mg/mL gives 2 mL per dose. This is a straightforward single-step calculation: 50 ÷ 25 = 2. No rounding is required because the result is already a whole number, and a leading zero is not applicable since the answer is greater than one. A common error students make is inverting the formula — for example, dividing 25 by 50 — which would give 0.5 mL, an incorrect answer that underdoses the client. Another potential mistake is confusing the total vial concentration with the per-dose amount ordered. It is also important to note that chlorpromazine (Thorazine) is a first-generation antipsychotic used for acute management of hallucinations in schizophrenia; IM administration provides more rapid onset than oral dosing and is appropriate in acutely agitated or symptomatic clients. The nurse should observe the client for adverse effects such as orthostatic hypotension, extrapyramidal symptoms, and sedation after administration. The correct answer of 2 mL matches the keyed answer.