19. 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? A. 7.5 B. 17.5 C. 75 D. 175
Answer: B
17.5 mg of amphotericin B is needed to fill the order.
To calculate the required dosage of amphotericin B, we first need to convert the patient's weight from pounds to kilograms. The patient's weight of 154 lb converts to approximately 70 kg (154 lb ÷ 2.2). Therefore, the dosage of 0.25 mg/kg results in a total of 17.5 mg (0.25 mg/kg × 70 kg).
A) 7.5
This option is incorrect as it underestimates the required dosage. Given the calculation, 0.25 mg/kg for a patient weighing 70 kg results in 17.5 mg, making 7.5 mg insufficient.
B) 17.5
This option is correct because it accurately reflects the calculated dosage based on the patient’s weight. By converting 154 lb to kg and applying the prescribed dosage of 0.25 mg/kg, the total needed is indeed 17.5 mg.
C) 75
This option is incorrect as it exceeds the calculated requirement. The calculation based on the patient's weight does not support a dosage of 75 mg, which is significantly higher than necessary.
D) 175
This option is also incorrect, as it greatly overestimates the dosage required. The calculation shows that the needed amount is only 17.5 mg, making 175 mg far too high for this patient.
Conclusion
The correct answer is 17.5 mg because it aligns perfectly with the dosage calculation based on the patient's weight. All other options either underestimate or overestimate the required amount, demonstrating a lack of adherence to the prescribed dosage per kilogram based on the patient's actual weight.