85. A patient who weighs 154 lb has a medication order for amphotericin B. The dosage of 0.25 mg/kg is to be added to 500 mL of D5W. How much amphotericin B in mg is needed to fill the order?
Answer: B
17.5 mg of amphotericin B is needed to fill the order.
To determine the required dosage of amphotericin B, first convert the patient's weight from pounds to kilograms. The calculation shows that the patient weighs approximately 70 kg. By multiplying this weight by the prescribed dosage of 0.25 mg/kg, the total required dosage is calculated to be 17.5 mg.
A) 7.5
This option is incorrect because it underestimates the required dose. If we were to calculate using a weight of 30 kg (which is incorrect), it would yield a dosage of 7.5 mg, but this does not reflect the patient’s actual weight of 70 kg.
B) 17.5
This option is correct as it accurately reflects the required dosage based on the patient’s weight. The calculation (70 kg x 0.25 mg/kg) results in 17.5 mg of amphotericin B, which fulfills the medication order perfectly.
C) 75
This option is incorrect as it significantly overestimates the required dosage. Calculating with a weight of 300 kg (which is unrealistic for this patient) would yield this amount, indicating a misunderstanding of the conversion from pounds to kilograms and the dosage calculation.
D) 175
This option is also incorrect because it greatly exceeds the necessary dosage. This would imply a calculation based on a weight of 700 kg, which is not applicable to the patient, leading to an erroneous conclusion.
Conclusion
The correct dosage of 17.5 mg is derived from accurately converting the patient's weight and applying the prescribed dosage rate. Options A, C, and D fail due to miscalculations of the patient’s weight and incorrect application of the dosage formula, ultimately leading to incorrect results. Thus, option B is the only choice that aligns with the required medical order.