A patient with neuroleptic malignant syndrome has been prescribed dantrolene 1.5 mg/kg IV. The patient weighs 132 pounds. The label on the 250 mg vial reads, “Reconstitute with 5 mL sterile water for injection, USP. Reconstitution yields 50 mg/mL.”. How many mL should the nurse administer?

Step 1 is to convert the patient’s weight from pounds to kilograms since the dosage is prescribed in mg/kg. We know that 1 kg is approximately 2.20462 pounds. So, the patient’s weight in kilograms is 132 pounds ÷ 2.20462 = 59.87 kg. Step 2 is to calculate the total dosage of dantrolene needed. The prescribed dosage is 1.5 mg/kg. So, the total dosage is 1.5 mg/kg × 59.87 kg = 89.81 mg. Step 3 is to calculate the volume of reconstituted dantrolene solution needed to provide the total dosage. The reconstituted solution has a concentration of 50 mg/mL. So, the volume needed is 89.81 mg ÷ 50 mg/mL = 1.80 mL.