A patient has an ampule of digoxin injection containing 500 mcg in 2 ml. How much volume is required to deliver a dose of 0.4 mg?

To determine the correct volume needed to deliver a dose of 0.4 mg of digoxin from an ampule containing 500 mcg in 2 ml, it is first essential to convert all units to be consistent. Since the given dose is in milligrams and the concentration in micrograms, converting the dose is the first step.

0.4 mg is equivalent to 400 mcg (since 1 mg = 1000 mcg). Now we know that the ampule contains 500 mcg in a total volume of 2 ml. To find out how much volume is necessary to obtain 400 mcg, we can set up a simple ratio:

• The concentration of the ampule is 250 mcg/ml (since 500 mcg/2 ml = 250 mcg/ml).

• To find the volume required to provide 400 mcg, use the formula:

[ \text{Volume} = \frac{\text{Desired Dose}}{\text{Concentration}} ]

Substituting the known values:

[ \text{Volume} = \frac{400 \text{ mcg}}{250 \text{ mcg/ml}} = 1.6 \text{ ml} ]