Question

A 142-lb patient was receiving filgrastim (NEUPOGEN) in doses of 10 mcg/kg/day when, as a result of successful blood tests, the dose was lowered to 6 mcg/kg/day. Using an injection containing 0.3 mg filgrastim per 0.5 mL, calculate the previous and new dose to be administered. a. 17.7 mL and 64.6 mL b. 5.23 mL and 3.14 mL c. 1.08 mL and 0.65 mL d. 3.87 mL and 2.3 mL

Answer 1

To calculate the filgrastim dose, the patient's weight was converted from pounds to kilograms. The original and new doses were calculated using the patient's weight, the dosage in micrograms per kilogram, and the drug's concentration in milliliters to arrive at approximately 1.08 mL for the previous dose and 0.65 mL for the new dose.

Step-by-step explanation:

To calculate both the previous and new dose of filgrastim to be administered to a 142-lb patient, we first need to convert the patient's weight from pounds to kilograms, because the dosage is given in micrograms per kilogram of body weight. We know that 1 kilogram is approximately equal to 2.2 pounds. After calculating the weight in kilograms, we can find the total dosage in micrograms and then convert that to milliliters using the concentration of the medication (0.3 mg per 0.5 mL).

Step-by-Step Calculation:

1. Convert the patient's weight from pounds to kilograms:
   
   142 lb × (1 kg / 2.2 lb) = 64.55 kg (rounded to two decimal places).
2. Calculate the previous dose in micrograms:
   
   64.55 kg × 10 mcg/kg = 645.5 mcg = 0.6455 mg.
3. Calculate the previous dose in milliliters:
   
   (0.6455 mg × 0.5 mL) / 0.3 mg = 1.0758 mL ≈ 1.08 mL.
4. Calculate the new dose in micrograms:
   
   64.55 kg × 6 mcg/kg = 387.3 mcg = 0.3873 mg.
5. Calculate the new dose in milliliters:
   
   (0.3873 mg × 0.5 mL) / 0.3 mg = 0.6455 mL ≈ 0.65 mL.

The previous dose to be administered is approximately 1.08 mL and the new dose is approximately 0.65 mL. This aligns with choice (c) 1.08 mL and 0.65 mL.