A nurse is preparing to administer phenobarbital 1.75 mg/kg PO to a client who weighs 178 lb. Available is phenobarbital 20 mg/5 mL. How many mL should the nurse administer? (Round the answer to the nearest whole number. Use a leading zero if it applies. Do not use a trailing zero.)

Calculation: Convert the client's weight from pounds (lb) to kilograms (kg). Weight in kg = 178 lb / 2.2 lb/kg = 80.9090 kg. Calculate the desired dose in milligrams (mg). Desired dose (mg) = 1.75 mg/kg × 80.9090 kg = 141.59075 mg. Available concentration of the medication = 20 mg/5 mL. Calculate the volume in milliliters (mL) to administer. Volume (mL) = Desired dose (mg) / (Available concentration (mg) / Available volume (mL)) = 141.59075 mg / (20 mg / 5 mL) = 141.59075 mg / 4 mg/mL = 35.3977 mL. Round the answer to the nearest whole number. = 35 mL.