A child with a seizure disorder receives a prescription for phenytoin 20 mg by mouth every 8 hours. The suspension is available in 125 mg/5 mL. How many mL should the nurse administer? (Enter the numerical value only. If rounding is required, round to the nearest tenth.)

To calculate the dose of phenytoin, use the formula: Dose (mL) = (Desired dose x Volume) / Stock dose - Plug in the values: Dose (mL) = (20 mg x 5 mL) / 125 mg - Simplify and solve: Dose (mL) = 0.8 mL - The nurse should administer 0.8 mL of phenytoin suspension every 8 hours.