Question

q5. a physician orders a single dose of 0.1 g of a drug for a child who weighs 51 kg with a height of 135 cm. the recommended pediatric dosage is 60 to 80 mg/m2/wk, and its strength is 25 mg/ml. is this a safe dose? if yes, how many milliliters should this child be given?

Explanation:

Step1: Calculate Body Surface Area (BSA)

Use the Mosteller formula: \( BSA = \sqrt{\frac{height(cm) \times weight(kg)}{3600}} \)
\( height = 135\ cm \), \( weight = 51\ kg \)
\( BSA = \sqrt{\frac{135 \times 51}{3600}} = \sqrt{\frac{6885}{3600}} \approx \sqrt{1.9125} \approx 1.383\ m^2 \)

Step2: Calculate Recommended Dosage Range

Lower limit: \( 60\ mg/m^2/wk \times 1.383\ m^2 \approx 82.98\ mg/wk \)
Upper limit: \( 80\ mg/m^2/wk \times 1.383\ m^2 \approx 110.64\ mg/wk \)
The ordered dose is \( 0.1\ g = 100\ mg \) (single dose, assuming weekly? Wait, the problem says "single dose" but dosage is per week? Wait, maybe the dosage is per dose? Wait, the problem says "recommended pediatric dosage is 60 to 80 mg/m²/wk" – maybe it's a weekly dose, but the ordered is a single dose? Wait, no, maybe the dosage is per dose. Wait, maybe the problem has a typo, but let's check: ordered dose is 0.1 g = 100 mg. The BSA is ~1.383 m². So per m², the ordered dose is 100 mg / 1.383 m² ≈ 72.3 mg/m². Which is between 60 and 80 mg/m², so safe.

Step3: Calculate Volume of Drug

Concentration is 25 mg/mL. Dose is 100 mg.
Volume \( V = \frac{Dose}{Concentration} = \frac{100\ mg}{25\ mg/mL} = 4\ mL \)

Answer:

Yes, it is a safe dose. The child should be given 4 milliliters.