Dosage Calculation Practice Questions

Dosage calculations are a crucial aspect of healthcare, ensuring that patients receive the correct amount of medication. This practice is essential for nurses, pharmacists, and other healthcare professionals. To master dosage calculations, consistent practice is key. This article provides a collection of practice questions covering common dosage calculation scenarios, along with detailed solutions to help you develop your skills in this area.

Practice Questions

1. Scenario: A physician orders 500 mg of medication to be administered intravenously. The available medication is in a 1000 mg vial. How many milliliters (mL) should be administered if the concentration of the medication is 250 mg/mL?
2. Scenario: A patient is prescribed 250 mg of medication orally every 8 hours. The available medication is in a 500 mg tablet. How many tablets should the patient take per day?
3. Scenario: A physician orders 1000 mL of intravenous fluids to be infused over 8 hours. What is the infusion rate in milliliters per hour (mL/hr)?
4. Scenario: A patient is prescribed 10 mg/kg of medication. The patient weighs 75 kg. What is the total dosage in milligrams (mg)?
5. Scenario: A physician orders 250 mg of medication to be administered intravenously over 30 minutes. The available medication is in a 1000 mg vial. The concentration of the medication is 250 mg/mL. What is the infusion rate in milliliters per minute (mL/min)?

Solutions

1. Solution:

   First, determine the volume of medication needed. Since the concentration is 250 mg/mL, and we need 500 mg, we can use the following formula:

   Volume = (Desired dose) / (Concentration)

   Volume = (500 mg) / (250 mg/mL) = 2 mL

   Therefore, 2 mL of the medication should be administered.

2. Solution:

   The patient needs 250 mg of medication every 8 hours. Since the available medication is in a 500 mg tablet, the patient needs to take half a tablet every 8 hours.

   To calculate the total tablets per day, we can use the following formula:

   Total tablets = (Number of doses per day) x (Dosage per dose)

   Total tablets = (3 doses per day) x (0.5 tablets per dose) = 1.5 tablets per day

3. Solution:

   The infusion rate is calculated by dividing the total volume of fluids by the infusion time. In this case, the infusion rate is:

   Infusion rate = (Total volume) / (Infusion time)

   Infusion rate = (1000 mL) / (8 hours) = 125 mL/hr

4. Solution:

   To calculate the total dosage, multiply the prescribed dosage per kilogram by the patient’s weight. In this case, the total dosage is:

   Total dosage = (Dosage per kg) x (Patient weight)

   Total dosage = (10 mg/kg) x (75 kg) = 750 mg

5. Solution:

   First, calculate the total volume of medication needed using the desired dose and the concentration:

   Volume = (Desired dose) / (Concentration)

   Volume = (250 mg) / (250 mg/mL) = 1 mL

   Next, calculate the infusion rate in milliliters per minute:

   Infusion rate = (Total volume) / (Infusion time)

   Infusion rate = (1 mL) / (30 minutes) = 0.033 mL/min

Tips for Dosage Calculations

• Always double-check your calculations and make sure your units are consistent.
• Use a calculator and make sure it is set to the correct units.
• Use a reliable drug reference guide to confirm the drug’s concentration and available dosage forms.
• Practice regularly to improve your accuracy and confidence.
• If you are unsure about any dosage calculation, consult with a pharmacist or other qualified healthcare professional.

By practicing these dosage calculation questions and following these tips, you can enhance your skills and ensure safe and accurate medication administration.