Writing a Paediatric Dose Card Where the Stock Items Do Not Fit the Prescription
A four-year-old girl weighing 16 kg is brought to the paediatric outpatient department of a sub-divisional hospital with fever of 39.2 °C and a sore throat. The medical officer prescribes paracetamol 15 mg/kg per dose every 6 hours, and amoxicillin 25 mg/kg per day in two divided doses. The hospital pharmacy stocks paracetamol suspension labelled 125 mg per 5 mL in 60 mL bottles, amoxicillin capsules of 250 mg, and amoxicillin dry syrup labelled 125 mg per 5 mL. The mother says that at home she has been giving 'two spoonfuls' of the same paracetamol syrup whenever the fever seemed high, sometimes six times in a day, using a household teaspoon. The staff nurse must write the dose card and counsel the mother before discharge, and must do so without contradicting the prescriber.
1. Calculate the paracetamol dose per administration in millilitres, the volume used per day, and how many bottles are needed for a three-day course.
Read the worked answer
Dose = 15 mg/kg × 16 kg = 240 mg per dose. Concentration = 125 mg per 5 mL = 25 mg/mL. Volume per dose = 240 / 25 = 9.6 mL.
Four doses a day (every 6 hours) = 4 × 9.6 = 38.4 mL/day. Three days = 115.2 mL. One 60 mL bottle lasts 60/38.4 = 1.56 days, so a single bottle would run out during the second day. Two bottles (120 mL) cover the course with a small margin.
Judgement points: 9.6 mL is a measured volume and should be given with the oral syringe or the measuring cup supplied, not a household spoon. Rounding 9.6 mL to 10 mL is acceptable clinically (250 mg), but rounding the number of bottles down is not - the family must not be sent home with 60 mL for a three-day course. The concentration must be confirmed on the label each time, because 125 mg/5 mL and 250 mg/5 mL bottles look alike.
2. Calculate the amoxicillin dose and decide which stock item should be dispensed. Explain why the capsules are unsuitable.
Read the worked answer
Total daily dose = 25 mg/kg × 16 kg = 400 mg/day, in two divided doses = 200 mg per dose.
Against the capsule: 200 mg cannot be obtained from a 250 mg capsule without opening it and splitting the powder by eye. That produces unacceptable variation, is unpalatable, and is not recommended for a child of this age. Splitting the dose is a prescriber's decision, not something the nurse or pharmacist improvises.
Against the suspension: 125 mg/5 mL = 25 mg/mL, so 200 mg = 8 mL per dose, twice daily, i.e. 16 mL/day.
Judgement point: the prescription is written in mg/kg, but the stock is in a form that cannot deliver that amount. The nurse's task is to find the stock form that matches the prescription, not to modify the prescription to suit the stock. If no oral suspension were available, the correct step is to contact the prescriber for an alternative formulation, not to dispense a divided capsule.
3. The mother has been giving two household teaspoons (about 10 mL) up to six times in 24 hours. Quantify this practice against the safe maximum and plan the counselling.
Read the worked answer
10 mL of 125 mg/5 mL = 250 mg per dose. Six doses = 1500 mg/day. Per kilogram: 1500/16 = 93.8 mg/kg/day.
The accepted maximum for paracetamol in children is 60 mg/kg/day (15 mg/kg four times a day), and even short-term some units will not exceed 75 mg/kg/day. So the mother is at roughly 1.5 times the ceiling, and one 60 mL bottle would be emptied in a single day.
The prescribed regimen is 240 mg four times = 960 mg/day = 60 mg/kg/day - exactly at the ceiling, with no room for extra doses. Counselling must therefore cover: the correct volume (9.6 mL) and the correct interval (not less than 4 hours, four times a day); why a household teaspoon is not a measure, since spoons vary from 3 to 7 mL; what to do if the fever persists despite the correct dose - return to the clinic rather than add a dose; and why the paracetamol bottle must be kept out of the child's reach.