A physician writes the following medication order for a 3 year old girl (weight 35 lbs) admitted to the hospital:

Propranolol 0.17 mg/kg/dose Q8H x 1 day

Propranolol 0.33 mg/kg/dose Q8H x 1 day

Propranolol 0.67 mg/kg/dose Q8H x 3 days

The pharmacy has the following recipe for compounding propranolol as an oral suspension. The suspension may be stored in the refrigerator for up to 45 days.

i) How much (in ml) of the above suspension would you inform the nurse to administer to the patient per dose during the first three days. (3 marks)

Concentration of propranolol suspension:

3 * 40 mg = 120 mg

120 mg/120 ml -> 1mg/ml

1 lbs = 0.45 kg (lbs to kg conversion ratio needs to be memorised)

Weight of child in kg: 35 lbs = 15.75 kg

Day 1: 0.17 * 15.75 = 2.68 mg -> 2.68 ml

Day 2: 0.33 * 15.75 = 5.20 mg -> 5.20 ml

Day 3: 0.67 * 15.75 * 3 = 10.55 mg -> 10.55 ml

The number of decimal places in your answer may be guided by the number of decimal places used by the examiner.

ii) A week after admission the patient is discharged with a prescription for propranolol 0.67 mg/kg/dose Q8H for 20 days. How much of each ingredient would you need to prepare a sufficient amount to dispense? (3 marks)

Amount of propranolol needed in total for 20 days in mg:

0.67 * 15.75 * 3 * 20 = 633.15 mg

The propranolol comes in 40 mg tablets. 633.15/40 = 15.8 tablets

Use 16 tablets

16*40 = 640 mg

Quantity of propranolol in above suspension: 120mg (in 120 ml)

Propranolol: Conversion ratio -> 640/120 (same as 16/3)

Using the same ratio convert the rest of the ingredients:

Distilled water: 2.4 * (16/3) = 12.8 ml

Citric acid 25% solution: 0.5 * (16/3) = 2.67 ml

Simple syrup: 120 * (16/3) = 640 ml