A nurse is preparing to administer tobramycin 3 mg/kg/day IM in three divided doses to a client who weighs 85 kg. The amount available is tobramycin 40 mg/ml. How many mL should the nurse administer per dose? (Round the answer to the nearest tenth. Use a leading zero if it applies. Do not use a trailing zero.)
The Correct answer and Explanation is:
To calculate the amount of tobramycin to administer per dose, we start by determining the total daily dose based on the client’s weight and the prescribed dosage. The nurse is instructed to administer tobramycin at a rate of 3 mg/kg/day, and the client weighs 85 kg.
- Calculate the Total Daily Dose:
[
\text{Total Daily Dose} = \text{Dosage per kg} \times \text{Weight}
]
[
\text{Total Daily Dose} = 3 \, \text{mg/kg} \times 85 \, \text{kg} = 255 \, \text{mg}
] - Determine the Dosage per Dose:
The total daily dose will be divided into three doses. Therefore, we divide the total daily dose by 3:
[
\text{Dose per administration} = \frac{\text{Total Daily Dose}}{3}
]
[
\text{Dose per administration} = \frac{255 \, \text{mg}}{3} = 85 \, \text{mg}
] - Convert the Dose to mL:
Now that we know the nurse needs to administer 85 mg per dose, we need to convert this amount to mL using the concentration of tobramycin available (40 mg/mL):
[
\text{Volume to administer} = \frac{\text{Dose (mg)}}{\text{Concentration (mg/mL)}}
]
[
\text{Volume to administer} = \frac{85 \, \text{mg}}{40 \, \text{mg/mL}} = 2.125 \, \text{mL}
] - Round to the Nearest Tenth:
Finally, we round 2.125 mL to the nearest tenth:
[
\text{Rounded Volume} = 2.1 \, \text{mL}
]
Thus, the nurse should administer 2.1 mL of tobramycin per dose.
Explanation
In this calculation, we used a step-by-step approach to ensure accuracy and clarity. First, we established the total dosage required for the client based on their weight and the prescribed dosage per kilogram. This method is crucial for safe medication administration, especially when dosing is weight-dependent. Next, we divided the total daily dosage by the number of doses to ensure the client receives the correct amount at each administration. Finally, by converting the required mg into mL based on the concentration provided, we completed the process, ensuring the result is presented to the required precision for safe and effective administration. This systematic approach is vital for nurses to prevent medication errors and ensure optimal patient care.