Final answer:
To achieve the desired concentration of 1000 mcg/100 mL from a 0.4 mg/mL scopolamine solution, 2.5 mL of stock solution should be added to the bag. Since this is not an option, the closest approximation from the choices provided would be to add 2 mL.
Step-by-step explanation:
To prepare a scopolamine solution with a concentration of 1000 micrograms (mcg) per 100 mL from a stock solution of 0.4 mg/mL, we need to calculate the volume of the stock solution to add to the 100 mL bag of normal saline (NS).
First, let's convert the desired concentration to milligrams (because the stock solution is in mg/mL):
- 1000 mcg = 1 mg (since 1 mg = 1000 mcg)
We want 1 mg in 100 mL of NS.
Using the dilution formula (C1V1 = C2V2), where:
- C1 is the concentration of the stock solution (0.4 mg/mL)
- V1 is the volume of the stock solution we are solving for
- C2 is the desired concentration in the 100 mL bag (1 mg per 100 mL, or 0.01 mg/mL)
- V2 is the final volume (100 mL)
We rearrange the formula to solve for V1:
- V1 = (C2V2) / C1
- V1 = (0.01 mg/mL * 100 mL) / 0.4 mg/mL
- V1 = (1 mg) / 0.4 mg/mL
- V1 = 2.5 mL
Answer: Add 2.5 mL of Scopolamine to the 100 mL bag of NS.
Note: Since the question options do not include 2.5 mL, if we're restricted to choose from the given options, 2 mL is the closest approximation to the correct answer. However, it is slightly less than the required amount. If the options are strict and only one can be chosen, then 2 mL is the best answer, but it is important to consult with a pharmacist or healthcare professional for precision in medication preparation.