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Young’s formula below is used to calculate the required dosages of medicine for children aged 1–12 years.
\(\text{Dosage}=\dfrac{\text{age of child (in years)}\ \times\ \text{adult dosage}}{\text{age of child (in years)}\ +\ 12}\)
How much of the medicine should be given to an 18-month-old child in a 24-hour period if each adult dosage is 27 mL? The medicine is to be taken every 8 hours by both adults and children.
\(C\)
\(\text{Age of child} = 18\ \text{months}=1.5\ \text{years}\)
| \(\text{Dosage}\) | \(=\dfrac{1.5\times 27}{1.5+12}\) |
| \(=3\ \text{mL}\) |
\(\text{Dosage every 8 hrs}\)
\(\therefore\ \text{In 24 hours, medicine given} = 3\times 3=9\ \text{mL}\)
\(\Rightarrow C\)
The formula \(D=\dfrac{2A}{15}\) is used to calculate the dosage of liquid paracetamol to be given to a child.
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The correct dosage of liquid paracetamol for Teddy is 6 mL.
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i. \(\text{0.8 mL}\)
ii. \(39\)
| i. | \(D\) | \(=\dfrac{2A}{15}\) |
| \(=\dfrac{2\times 6}{15}\) | ||
| \(=0.8\text{ mL}\) |
\(\therefore\ \text{Charlotte should be given a dosage of 0.8 mL}\)
ii. \(\text{Find}\ A\ \text{when}\ D=\text{6 mL}\)
| \(6\) | \(=\dfrac{2A}{15}\) |
| \(2A\) | \(=90\) |
| \(A\) | \(=45\) |
\(\therefore\ \text{Teddy is 45 months old and is 39 months}\)
\(\text{older than Charlotte.}\)
Young’s formula, shown below, is used to calculate the dosage of medication for children aged 1−12 years based on the adult dosage.
\(D=\dfrac{yA}{y + 12}\)
| where \(D\) | = dosage for children aged 1−12 years |
| \(y\) | = age of child (in years) |
| \(A\) | = Adult dosage |
A child’s dosage is calculated to be 15 mg, based on an adult dosage of 30 mg.
How old is the child in years?
\(D\)
| \(D\) | \(=\dfrac{yA}{y+12}\) |
| \(15\) | \(=\dfrac{30y}{y+12}\) |
| \(15(y+12)\) | \(=30y\) |
| \(15y+180\) | \(=30y\) |
| \(15y\) | \(=180\) |
| \(y\) | \(=12\) |
\(\Rightarrow D\)
Fried's formula is used to calculate the medicine dosages for children aged 1-2 years.
\(\text{Child dosage}=\dfrac{\text{Age(in months)}\times \text{adult dosage}}{150}\)
Liam is 1.75 years old and receives a daily dosage of 350 mg of a medicine.
According to Fried's formula, what would the appropriate adult daily dosage of the medicine be? (2 marks)
\(2500\ \text{mg}\)
\(1.75\ \text{years}=21\ \text{months}\)
| \(350\) | \(=\dfrac{21\times \text{adult dosage}}{150}\) |
| \(\therefore\ \text{adult dosage}\) | \(=\dfrac{350\times 150}{21}\) |
| \(=2500\ \text{mg}\) |
Clark’s formula, given below, is used to determine the dosage of medicine for children.
\(\text{Dosage}=\dfrac{\text{weight in kg × adult dosage}}{70}\)
For a particular medicine, the adult dosage is 220 mg and the correct dosage for a specific child is 45 mg.
How much does the child weigh, to the nearest kg? (2 marks)
\(14\ \text{kg}\)
\(45 =\dfrac{\text{weight}\times 220}{70}\)
| \(\therefore\ \text{weight}\) | \(=\dfrac{70\times 45}{220}\) |
| \(=14.318\dots\) | |
| \(\approx 14\ \text{kg (nearest kg)}\) |
Clark’s formula is used to determine the dosage of medicine for children.
\(\text{Dosage}=\dfrac{\text{weight in kg × adult dosage}}{70}\)
The adult daily dosage of a medicine contains 1750 mg of a particular drug.
A child who weighs 30 kg is to be given tablets each containing 125 mg of this drug.
How many tablets should this child be given daily? (2 marks)
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\(6\)
| \(\text{Dosage}\) | \(=\dfrac{30\times 1750}{70}\) |
| \(=750\ \text{mg}\) |
\(\text{Number of tablets per day}\)
\(=\dfrac{\text{Dosage}}{\text{mg per tablet}}\)
\(=\dfrac{750}{125}\)
\(=6\)
\(\therefore\ \text{The child should be given 6 tablets per day.}\)