A nurse is preparing to administer belimumab 10 mg/kg via intermittent IV bolus to a client who weighs 136 lb. Available is belimumab 80 mg/mL. How many mL should the nurse administer? (Round the answer to the nearest whole number. Use a leading zero if it applies. Do not use a trailing zero.)
The correct answer and Explanation is :
To calculate how many mL the nurse should administer, follow these steps:
Step 1: Convert the client’s weight from pounds (lb) to kilograms (kg).
- 136 lb ÷ 2.2 = 61.82 kg (round to 61.8 kg).
Step 2: Determine the total dosage required in mg.
- The prescribed dosage is 10 mg per kg of body weight. Therefore:
- 10 mg/kg × 61.8 kg = 618 mg.
Step 3: Calculate the volume to be administered.
- The available concentration of belimumab is 80 mg/mL.
- To determine the number of mL needed to administer 618 mg, use the following formula:
[
\text{Volume to administer} = \frac{\text{Dosage required (mg)}}{\text{Concentration (mg/mL)}} = \frac{618 \, \text{mg}}{80 \, \text{mg/mL}} = 7.725 \, \text{mL}
]
Step 4: Round to the nearest whole number.
- 7.725 mL rounds to 8 mL.
Final Answer: 8 mL
Explanation:
- Weight Conversion: Medication dosages are often calculated based on body weight in kilograms (kg), so it’s essential to convert from pounds to kilograms. The conversion factor is 1 kg = 2.2 lb.
- Dosage Calculation: The order specifies 10 mg of belimumab per kg of body weight. By multiplying the client’s weight (61.8 kg) by the ordered dose per kg (10 mg/kg), the total required dose is determined to be 618 mg.
- Volume Calculation: Since the available medication is in a concentration of 80 mg/mL, you can determine the volume to be administered by dividing the required dose (618 mg) by the concentration (80 mg/mL). This results in 7.725 mL, which is then rounded to the nearest whole number for ease of administration, yielding 8 mL.
- Practical Rounding: In nursing, when calculating IV medication volumes, rounding is done carefully to ensure accurate dosage without risking overdose or underdose. This is why the final volume is rounded to 8 mL, following standard guidelines.