The healthcare provider prescribes metoclopramide 7.5 mg/mL IM every 3 hours PRN vomiting for a client who is receiving chemotherapy. The nurse prepares an injection using a 2 mL prefilled syringe cartridge labeled, “metoclopramide 5 mg/mL.” How many mL should the nurse administer? (Enter numeric value only. If rounding is required, round to the nearest tenth.)
The correct answer and Explanation is :
To calculate how many mL of metoclopramide to administer, we use the following formula:
[
\text{Volume to administer (mL)} = \frac{\text{Prescribed dose (mg)}}{\text{Available concentration (mg/mL)}}
]
Step-by-step calculation:
- Prescribed dose: 7.5 mg
- Available concentration: 5 mg/mL
[
\text{Volume to administer} = \frac{7.5 \, \text{mg}}{5 \, \text{mg/mL}} = 1.5 \, \text{mL}
]
Answer:
The nurse should administer 1.5 mL.
Explanation:
In this scenario, the healthcare provider has prescribed metoclopramide 7.5 mg to be administered intramuscularly (IM) every 3 hours as needed for vomiting. The medication is supplied in a 2 mL prefilled syringe labeled with a concentration of 5 mg/mL.
When preparing a medication dosage, it is critical to ensure that the correct amount is drawn up to deliver the prescribed dose safely. The formula used above helps calculate how much of the solution to administer based on the prescribed dose and the available concentration.
- Prescribed dose: The provider has ordered 7.5 mg of metoclopramide.
- Available concentration: The concentration of the drug provided is 5 mg/mL, meaning each mL contains 5 mg of metoclopramide.
By dividing the prescribed dose by the concentration of the medication (7.5 mg ÷ 5 mg/mL), you get 1.5 mL, which is the volume needed to deliver the prescribed 7.5 mg dose.
After drawing up 1.5 mL, the nurse would administer it to the patient as ordered. This calculation ensures the correct dose is given, which is crucial in avoiding over- or under-dosing.