The physician orders phenobarbital (Luminal) IV to a child weighing 56 kg. The recommended dose is between 1 mg and 3 mg. How much should you give every 6 hours?
1 mg X kg = dose in 24 hours
1 mg X 56 kg = 56 mg in 24 hours
3 mg X 56 kg = 168 mg in 24 hours
Every 6 hours is equivalent to 4 doses
56 mg divided by 4 = 14 mg
168 mg divided by 4 = 42 mg
The safe dosage range in 4 divided doses is 14 mg to 42 mg per dose.