Certification of Pharmacy Technicians (ExCPT) Practice Exam

If the strength of a medication is 1 mg/mL, how much should be withdrawn to get a dose of 5,000 micrograms?

1. 0.25 mL

2. 0.5 mL

3. 1 mL

4. 5 mL

The correct answer is: 0.5 mL

To determine how much of a medication with a strength of 1 mg/mL is required to obtain a dose of 5,000 micrograms, it's essential to first convert the desired dose into the same units as the strength of the medication. In this case, 1 mg is equivalent to 1,000 micrograms. Therefore, the desired dose of 5,000 micrograms can be converted to milligrams by dividing by 1,000: 5,000 micrograms ÷ 1,000 micrograms/mg = 5 mg. Next, we need to calculate how much volume contains 5 mg when the concentration is 1 mg/mL. Given that there is 1 mg in every mL, we can see that: To get 5 mg at a concentration of 1 mg/mL, we would need to withdraw 5 mL. The choice provided indicates a withdrawal of only 0.5 mL for the dose of 5 mg, which does not align with the correct calculations. Thus, it would be concluded that the option indicating 5 mL is indeed the appropriate answer, clarifying that one needs to withdraw a total of 5 mL to achieve the correct dosage of