The physician orders Lanoxin elixir 90 mcg PO every morning.
Drug available: Lanoxin elixir 0.05 mg/mL
How many mL will be given?
The correct answer and Explanation is :
To calculate how many mL of Lanoxin elixir to administer, we use the formula:
[
\text{{Amount to give}} = \frac{{\text{{Desired dose}}}}{{\text{{Dose on hand}}}} \times \text{{Volume on hand}}
]
Step-by-step calculation:
- Desired dose: 90 mcg (this is the dose ordered by the physician).
- Dose on hand: The drug is available as 0.05 mg/mL.
- Convert the units: Since the desired dose is in micrograms (mcg), and the available dose is in milligrams (mg), we need to convert them to the same unit.
- 1 mg = 1000 mcg
- 0.05 mg = 0.05 mg × 1000 mcg = 50 mcg/mL.
- Plug in the values:
[
\text{{Amount to give}} = \frac{{90 \, \text{{mcg}}}}{{50 \, \text{{mcg/mL}}}} = 1.8 \, \text{{mL}}.
]
So, you will administer 1.8 mL of Lanoxin elixir.
Explanation:
When administering medication, it’s critical to ensure that the correct dosage is given. In this case, the ordered dose of Lanoxin (Digoxin) is 90 mcg, but the available concentration is given in mg. Since medications are often prescribed in different units than what’s available in stock, proper conversion is necessary.
In healthcare, errors in dosage calculations can lead to significant patient harm. Lanoxin, specifically, is a cardiac glycoside used to treat heart failure and arrhythmias. It has a narrow therapeutic range, meaning that both underdosing and overdosing can have severe consequences. Calculating the exact dosage ensures the patient’s safety and helps achieve the desired therapeutic effect.
In this case, once the units are converted, dividing the desired dose by the concentration gives the volume of medication to administer, which is 1.8 mL. Always double-check your work, especially when dealing with potent medications like Lanoxin.