Question

Tiffany is 5 yr. old and weighs 57lbs. The order reads: Macrodantin 50 mg po qid.

Step 1: Recommended dose guidelines: 5-7 mg/kg/24 hours. Supplied: 50 mg tab.

Step 2: Kg = ________________

Step 3: Safe dosage range: __________________________

Step 4: Maximum safe dose for 24 hours: _______________________

Step 5: Amount ordered for 24 hours: ______________________

Step 6: Is the ordered dose safe? _______________________

Step 7: Calculate amount to be given for single dose: _______________________

Answer 1

Step 2 : to convert weight from pound (lb) to kg divide to lbs by 2.205.

So 57 lb = 25.85 kg

Step 3 : safe dosage range

Recommended dose guidelines: 5-7 mg/kg/24 hours

As the child weighs 25.85 kg minimum dose is 5 x 25.85 = 129.25 mg

The maximum dose is 7 x 25.85 = 180.95 mg

The safe dose range is 129.25 - 180.95 mg

Step 4 : maximum safe dose

The maximum safe dose is 7 x 25.85 = 180.95 mg

Step 5 : the amount ordered is 50 mg po wid. It means 50 mg needs to be given 4 times in 24 hours.

So the amount ordered for 24 hours = 50 x 4 = 200 mg in 24 hours

Step 6 : as calculated in step 3 the safe dose range is 129.25 - 180.95 mg.

The dose ordered by physician is 200 mg in 24 hours which is exceeding the maximum dose of 180.95 mg. So the dose is not in safe order range.

Step 7 : amount to be given in single dose can be calculated as dose ordered/dose in hand x quantity

Dose ordered = 50mg

Dose in hand = 50 mg

Quantity = single dose i.e. 1

Amount to be given in single dose = 50/50 x 1 = 1 tablet

So 1 tablet of 50 mg needs to be given in single dose