Pharmacology Quiz: Titration And Infusion Rates
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Titration And Infusion RatesQuestion 1 of 20

A patient's blood pressure is not responding to a norepinephrine infusion that is currently at its maximum protocol dose of 0.5 mcg/kg/min. The patient weighs 80 kg and the infusion concentration is 8 mg in 250 mL. The protocol states 'If at max norepinephrine dose and MAP < 65, notify provider and anticipate order for vasopressin.' What is the current norepinephrine infusion rate in mL/hr?

37.5 mL/hr
50.0 mL/hr
62.5 mL/hr
75.0 mL/hr
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Pharmacology Quiz

Pharmacology Quiz: Titration And Infusion Rates

Practice Titration And Infusion Rates in Pharmacology with focused quiz questions that help you check what you know, review explanations, and build confidence with test-style prompts.

What this quiz covers

This quiz focuses on Titration And Infusion Rates, giving you a quick way to practice the rules, question types, and explanations that matter most for Pharmacology.

How to use this quiz

Try each quiz question before looking at the correct answer. Use the explanations to review missed ideas, then come back to similar questions until the pattern feels familiar.

All questions

Question 1

A patient's blood pressure is not responding to a norepinephrine infusion that is currently at its maximum protocol dose of 0.5 mcg/kg/min. The patient weighs 80 kg and the infusion concentration is 8 mg in 250 mL. The protocol states 'If at max norepinephrine dose and MAP < 65, notify provider and anticipate order for vasopressin.' What is the current norepinephrine infusion rate in mL/hr?

  1. 37.5 mL/hr
  2. 50.0 mL/hr
  3. 62.5 mL/hr
  4. 75.0 mL/hr (correct answer)
Explanation: The question asks for the infusion rate at the maximum dose, which requires a standard dose-to-rate calculation. The information about vasopressin is context for a decision-making scenario but not needed for the calculation.
  1. Calculate total dose in mcg/min: 0.5 mcg/kg/min × 80 kg = 40 mcg/min.
  2. Convert dose to mcg/hr: 40 mcg/min × 60 min/hr = 2400 mcg/hr.
  3. Calculate concentration: 8 mg = 8000 mcg. Concentration = 8000 mcg / 250 mL = 32 mcg/mL.
  4. Calculate rate: Rate = Dose / Concentration = 2400 mcg/hr / 32 mcg/mL = 75 mL/hr.
A (37.5 mL/hr) would be the rate for a dose of 0.25 mcg/kg/min (half the max dose). B (50.0 mL/hr) might be selected if the concentration was incorrectly calculated using 4 mg in the bag. C (62.5 mL/hr) is incorrect and does not correspond to a common calculation error.

Question 2

An order is written to titrate a milrinone infusion by +0.05 mcg/kg/min. The patient weighs 65 kg and the infusion bag has a concentration of 20 mg in 100 mL. By how many mL/hr should the nurse increase the infusion rate?

  1. 1.0 mL/hr (correct answer)
  2. 1.6 mL/hr
  3. 2.5 mL/hr
  4. 3.3 mL/hr
Explanation: This question asks for the change in rate (Δ rate), not the new total rate.
  1. Calculate the dose change in mcg/min: 0.05 mcg/kg/min × 65 kg = 3.25 mcg/min.
  2. Convert the dose change to mcg/hr: 3.25 mcg/min × 60 min/hr = 195 mcg/hr.
  3. Calculate the infusion concentration: 20 mg = 20,000 mcg. Concentration = 20,000 mcg / 100 mL = 200 mcg/mL.
  4. Calculate the change in rate: Δ Rate = Δ Dose / Concentration = 195 mcg/hr / 200 mcg/mL = 0.975 mL/hr, which rounds to 1.0 mL/hr.
B (1.6 mL/hr) would be the increase for a titration of 0.08 mcg/kg/min. C (2.5 mL/hr) is incorrect; it might result from using the wrong weight or making a decimal error. D (3.3 mL/hr) might be the result if the concentration was assumed to be 10mg in 100mL.

Question 3

A patient with a hypertensive crisis is started on a sodium nitroprusside infusion. The order is to titrate by 0.2 mcg/kg/min every 5 minutes to a target MAP of 90 mmHg. The patient weighs 70 kg. The current dose is 0.5 mcg/kg/min, and the MAP is 110 mmHg. What is the new dose after one titration?

  1. 0.3 mcg/kg/min
  2. 0.5 mcg/kg/min
  3. 0.7 mcg/kg/min (correct answer)
  4. 1.0 mcg/kg/min
Explanation: Sodium nitroprusside is a vasodilator, so to lower the blood pressure (MAP 110 > target 90), the infusion rate must be increased. The question tests understanding of the drug's action in the context of titration.
  1. Determine titration direction: The patient is hypertensive (MAP 110), so the vasodilator dose needs to be increased.
  2. Apply titration amount: The protocol states to titrate by 0.2 mcg/kg/min.
  3. Calculate new dose: Current dose (0.5 mcg/kg/min) + titration amount (0.2 mcg/kg/min) = 0.7 mcg/kg/min.
A (0.3 mcg/kg/min) is incorrect. This would be a decrease in the dose, which would worsen the hypertension. B (0.5 mcg/kg/min) is the current dose, not the new dose after titration. D (1.0 mcg/kg/min) would be the dose after multiple titrations, not just one.

Question 4

A 68 kg patient with acute decompensated heart failure is on a dobutamine infusion at 10 mL/hr. The patient's blood pressure remains low at 85/50 mmHg with a MAP of 62 mmHg. The protocol states: 'If MAP is < 65 mmHg, increase dobutamine infusion by 2 mcg/kg/min.' The dobutamine concentration is 500 mg in 250 mL of D5W.

After the titration, what will the new infusion pump rate be in mL/hr?

  1. 4.1 mL/hr
  2. 10.0 mL/hr
  3. 14.1 mL/hr (correct answer)
  4. 18.2 mL/hr
Explanation: This problem requires calculating the current dose, adding the titration dose, and then finding the new rate.
  1. Calculate concentration: 500 mg / 250 mL = 2 mg/mL, which is 2000 mcg/mL.
  2. Calculate current dose rate: The pump is at 10 mL/hr. 10 mL/hr × 2000 mcg/mL = 20,000 mcg/hr.
  3. Convert current dose to mcg/kg/min: (20,000 mcg/hr ÷ 60 min/hr) ÷ 68 kg ≈ 4.9 mcg/kg/min.
  4. Determine the new dose: The protocol requires an increase of 2 mcg/kg/min. New dose = 4.9 + 2 = 6.9 mcg/kg/min.
  5. Calculate the new total dose in mcg/hr: 6.9 mcg/kg/min × 68 kg × 60 min/hr ≈ 28,152 mcg/hr.
  6. Calculate the new rate in mL/hr: 28,152 mcg/hr ÷ 2000 mcg/mL ≈ 14.1 mL/hr. A simpler way: Calculate the volume increase for the titration. Titration dose = 2 mcg/kg/min. Total titration dose = 2 mcg/kg/min * 68 kg = 136 mcg/min. Convert to mg/hr = 136 mcg/min * 60 min/hr / 1000 mcg/mg = 8.16 mg/hr. Convert to mL/hr = 8.16 mg/hr / 2 mg/mL = 4.08 mL/hr. New rate = 10 mL/hr + 4.08 mL/hr = 14.08 mL/hr, which rounds to 14.1 mL/hr. A (4.1 mL/hr) represents only the calculated increase in rate, not the new total rate. B (10.0 mL/hr) is the current rate before the required titration. D (18.2 mL/hr) would be the result of a significant calculation error, possibly increasing the dose by 5 mcg/kg/min instead of 2.

Question 5

A patient is receiving a diltiazem infusion at 10 mL/hr from a bag with a concentration of 125 mg in 125 mL D5W. The pharmacy sends a new, more concentrated bag containing 125 mg in 100 mL D5W. To maintain the same dose of diltiazem in mg/hr, the nurse should adjust the infusion pump to what new rate?

  1. 8.0 mL/hr (correct answer)
  2. 10.0 mL/hr
  3. 12.5 mL/hr
  4. 15.0 mL/hr
Explanation: The key is to maintain the same dose (mg/hr) when the concentration (mg/mL) changes.
  1. Calculate the current dose: The initial concentration is 125 mg / 125 mL = 1 mg/mL. The dose is 10 mL/hr × 1 mg/mL = 10 mg/hr.
  2. Calculate the new concentration: The new bag's concentration is 125 mg / 100 mL = 1.25 mg/mL.
  3. Calculate the new rate: To deliver the same 10 mg/hr dose with the new concentration, the rate must be adjusted: Rate = Dose / Concentration = 10 mg/hr / 1.25 mg/mL = 8 mL/hr.
B (10.0 mL/hr) is incorrect. Keeping the rate the same would increase the drug delivery to 12.5 mg/hr (10 mL/hr × 1.25 mg/mL). C (12.5 mL/hr) is incorrect. This error often comes from multiplying by the concentration change instead of dividing (10 mL/hr × 1.25 = 12.5 mL/hr). D (15.0 mL/hr) is an incorrect calculation without a clear logical basis.

Question 6

A patient receiving a nicardipine infusion at 12 mL/hr for hypertension has a blood pressure of 190/110 mmHg. The protocol states: 'For SBP > 180 mmHg, increase rate by 2.5 mg/hr every 15 minutes.' The nicardipine concentration is 25 mg in 250 mL.

What is the new infusion rate in mL/hr after making the required adjustment?

  1. 14.5 mL/hr
  2. 22.0 mL/hr
  3. 25.0 mL/hr
  4. 37.0 mL/hr (correct answer)
Explanation: This problem involves titrating a dose that is not weight-based.
  1. Calculate the concentration: 25 mg / 250 mL = 0.1 mg/mL.
  2. Calculate the current dose in mg/hr: 12 mL/hr × 0.1 mg/mL = 1.2 mg/hr.
  3. Determine the new dose: The protocol requires an increase of 2.5 mg/hr. New dose = 1.2 mg/hr + 2.5 mg/hr = 3.7 mg/hr.
  4. Calculate the new rate in mL/hr: New Rate = New Dose / Concentration = 3.7 mg/hr / 0.1 mg/mL = 37 mL/hr. A (14.5 mL/hr) is incorrect; it results from adding the dose change (2.5) directly to the rate (12), failing to account for concentration. B (22.0 mL/hr) is incorrect and may result from miscalculating the initial dose or the required rate. C (25.0 mL/hr) is the rate that would deliver exactly 2.5 mg/hr (2.5 mg/hr ÷ 0.1 mg/mL), but this is the change in dose, not the new total rate.

Question 7

A 100 kg patient is ordered to start a lidocaine infusion at 2 mg/min following a bolus. The standard pharmacy concentration is 2 g of lidocaine in 500 mL of D5W. At what rate in mL/hr should the nurse set the infusion pump?

  1. 15 mL/hr
  2. 30 mL/hr (correct answer)
  3. 45 mL/hr
  4. 60 mL/hr
Explanation: This calculation requires converting units and is not weight-based, making the patient's weight extraneous information.
  1. Convert dose to mg/hr: The ordered dose is 2 mg/min. To find the hourly dose, multiply by 60: 2 mg/min × 60 min/hr = 120 mg/hr.
  2. Calculate concentration: The bag contains 2 g, which is 2000 mg. The concentration is 2000 mg / 500 mL = 4 mg/mL.
  3. Calculate the rate: Rate = Dose / Concentration = 120 mg/hr / 4 mg/mL = 30 mL/hr.
A (15 mL/hr) would be the rate for a dose of 1 mg/min. C (45 mL/hr) would be the rate for a dose of 3 mg/min. D (60 mL/hr) would be the rate for a dose of 4 mg/min, or if the concentration was miscalculated as 2 mg/mL.

Question 8

A patient is receiving an infusion of propofol at 15 mL/hr. Two hours later, the rate is increased to 20 mL/hr. After another three hours, the rate is decreased to 18 mL/hr, which is maintained for one hour before the infusion is discontinued. What is the total volume of propofol infused over the entire 6-hour period?

  1. 53 mL
  2. 98 mL
  3. 108 mL (correct answer)
  4. 113 mL
Explanation: This question requires calculating the volume infused during three distinct time periods and then summing them.
  1. Period 1: 15 mL/hr for 2 hours = 15 × 2 = 30 mL.
  2. Period 2: 20 mL/hr for 3 hours = 20 × 3 = 60 mL.
  3. Period 3: 18 mL/hr for 1 hour = 18 × 1 = 18 mL.
  4. Total Volume: 30 mL + 60 mL + 18 mL = 108 mL.
A (53 mL) is incorrect and may result from adding the rates (15+20+18) instead of the volumes. B (98 mL) is incorrect; this may result from a calculation error in one of the periods. D (113 mL) is incorrect and may result from misreading the time frames, for example, running the 20 mL/hr rate for 4 hours instead of 3.

Question 9

A patient is receiving an amiodarone maintenance infusion post-bolus. The order is for 0.5 mg/min for 18 hours. The IV bag contains 450 mg of amiodarone in 250 mL of D5W. What is the correct infusion rate in mL/hr?

  1. 12.5 mL/hr
  2. 16.7 mL/hr (correct answer)
  3. 20.8 mL/hr
  4. 33.3 mL/hr
Explanation: This is a non-weight-based calculation requiring unit conversions.
  1. Convert dose from mg/min to mg/hr: 0.5 mg/min × 60 min/hr = 30 mg/hr.
  2. Calculate concentration: 450 mg / 250 mL = 1.8 mg/mL.
  3. Calculate rate in mL/hr: Rate = Dose / Concentration = 30 mg/hr / 1.8 mg/mL ≈ 16.7 mL/hr. The 18-hour duration is information about the order's length but not needed for the rate calculation.
A (12.5 mL/hr) might result from a calculation error, possibly in the concentration. C (20.8 mL/hr) would be the rate if the concentration was 900mg in 500mL and the dose was 1mg/min. D (33.3 mL/hr) would be the correct rate for a dose of 1 mg/min with this concentration.

Question 10

A vasopressin infusion is ordered to start at 0.03 units/minute. The pharmacy supplies a bag containing 50 units of vasopressin in 250 mL of NS. What is the correct initial rate for the infusion pump in mL/hr?

  1. 3.0 mL/hr
  2. 6.0 mL/hr
  3. 9.0 mL/hr (correct answer)
  4. 12.0 mL/hr
Explanation: This problem requires converting a dose from units/minute to a rate in mL/hr.
  1. Convert dose to units/hr: 0.03 units/min × 60 min/hr = 1.8 units/hr.
  2. Calculate concentration: 50 units / 250 mL = 0.2 units/mL.
  3. Calculate rate: Rate = Dose / Concentration = 1.8 units/hr / 0.2 units/mL = 9 mL/hr.
A (3.0 mL/hr) would be the rate for a dose of 0.01 units/min. B (6.0 mL/hr) would be the rate for a dose of 0.02 units/min. D (12.0 mL/hr) would be the rate for a dose of 0.04 units/min.

Question 11

An infusion pump is alarming for 'occlusion downstream'. After resolving the occlusion, the nurse notes the pump screen displays 'Volume to be infused: 150 mL' and 'Time remaining: 2 hr 30 min'.

Based on the information on the pump screen, at what rate in mL/hr is the infusion currently programmed to run?

  1. 50 mL/hr
  2. 60 mL/hr (correct answer)
  3. 75 mL/hr
  4. 100 mL/hr
Explanation: This question tests the fundamental relationship Rate = Volume / Time, requiring a conversion of the time unit.
  1. Convert time to hours: 2 hr 30 min = 2.5 hours.
  2. Calculate rate: Rate = Total Volume / Total Time = 150 mL / 2.5 hr = 60 mL/hr.
A (50 mL/hr) would be the rate if the time remaining was 3 hours. C (75 mL/hr) would be the rate if the time remaining was 2 hours. D (100 mL/hr) would be the rate if the time remaining was 1.5 hours.

Question 12

A patient is receiving an infusion of propofol at 15 mL/hr. Two hours later, the rate is increased to 20 mL/hr. After another three hours, the rate is decreased to 18 mL/hr, which is maintained for one hour before the infusion is discontinued. What is the total volume of propofol infused over the entire 6-hour period?

  1. 53 mL
  2. 98 mL
  3. 108 mL (correct answer)
  4. 113 mL
Explanation: This question requires calculating the volume infused during three distinct time periods and then summing them.
  1. Period 1: 15 mL/hr for 2 hours = 15 × 2 = 30 mL.
  2. Period 2: 20 mL/hr for 3 hours = 20 × 3 = 60 mL.
  3. Period 3: 18 mL/hr for 1 hour = 18 × 1 = 18 mL.
  4. Total Volume: 30 mL + 60 mL + 18 mL = 108 mL.
A (53 mL) is incorrect and may result from adding the rates (15+20+18) instead of the volumes. B (98 mL) is incorrect; this may result from a calculation error in one of the periods. D (113 mL) is incorrect and may result from misreading the time frames, for example, running the 20 mL/hr rate for 4 hours instead of 3.

Question 13

A patient is receiving a diltiazem infusion at 10 mL/hr from a bag with a concentration of 125 mg in 125 mL D5W. The pharmacy sends a new, more concentrated bag containing 125 mg in 100 mL D5W. To maintain the same dose of diltiazem in mg/hr, the nurse should adjust the infusion pump to what new rate?

  1. 8.0 mL/hr (correct answer)
  2. 10.0 mL/hr
  3. 12.5 mL/hr
  4. 15.0 mL/hr
Explanation: The key is to maintain the same dose (mg/hr) when the concentration (mg/mL) changes.
  1. Calculate the current dose: The initial concentration is 125 mg / 125 mL = 1 mg/mL. The dose is 10 mL/hr × 1 mg/mL = 10 mg/hr.
  2. Calculate the new concentration: The new bag's concentration is 125 mg / 100 mL = 1.25 mg/mL.
  3. Calculate the new rate: To deliver the same 10 mg/hr dose with the new concentration, the rate must be adjusted: Rate = Dose / Concentration = 10 mg/hr / 1.25 mg/mL = 8 mL/hr.
B (10.0 mL/hr) is incorrect. Keeping the rate the same would increase the drug delivery to 12.5 mg/hr (10 mL/hr × 1.25 mg/mL). C (12.5 mL/hr) is incorrect. This error often comes from multiplying by the concentration change instead of dividing (10 mL/hr × 1.25 = 12.5 mL/hr). D (15.0 mL/hr) is an incorrect calculation without a clear logical basis.

Question 14

A 100 kg patient is ordered to start a lidocaine infusion at 2 mg/min following a bolus. The standard pharmacy concentration is 2 g of lidocaine in 500 mL of D5W. At what rate in mL/hr should the nurse set the infusion pump?

  1. 15 mL/hr
  2. 30 mL/hr (correct answer)
  3. 45 mL/hr
  4. 60 mL/hr
Explanation: This calculation requires converting units and is not weight-based, making the patient's weight extraneous information.
  1. Convert dose to mg/hr: The ordered dose is 2 mg/min. To find the hourly dose, multiply by 60: 2 mg/min × 60 min/hr = 120 mg/hr.
  2. Calculate concentration: The bag contains 2 g, which is 2000 mg. The concentration is 2000 mg / 500 mL = 4 mg/mL.
  3. Calculate the rate: Rate = Dose / Concentration = 120 mg/hr / 4 mg/mL = 30 mL/hr.
A (15 mL/hr) would be the rate for a dose of 1 mg/min. C (45 mL/hr) would be the rate for a dose of 3 mg/min. D (60 mL/hr) would be the rate for a dose of 4 mg/min, or if the concentration was miscalculated as 2 mg/mL.

Question 15

An order is written to titrate a milrinone infusion by +0.05 mcg/kg/min. The patient weighs 65 kg and the infusion bag has a concentration of 20 mg in 100 mL. By how many mL/hr should the nurse increase the infusion rate?

  1. 1.0 mL/hr (correct answer)
  2. 1.6 mL/hr
  3. 2.5 mL/hr
  4. 3.3 mL/hr
Explanation: This question asks for the change in rate (Δ rate), not the new total rate.
  1. Calculate the dose change in mcg/min: 0.05 mcg/kg/min × 65 kg = 3.25 mcg/min.
  2. Convert the dose change to mcg/hr: 3.25 mcg/min × 60 min/hr = 195 mcg/hr.
  3. Calculate the infusion concentration: 20 mg = 20,000 mcg. Concentration = 20,000 mcg / 100 mL = 200 mcg/mL.
  4. Calculate the change in rate: Δ Rate = Δ Dose / Concentration = 195 mcg/hr / 200 mcg/mL = 0.975 mL/hr, which rounds to 1.0 mL/hr.
B (1.6 mL/hr) would be the increase for a titration of 0.08 mcg/kg/min. C (2.5 mL/hr) is incorrect; it might result from using the wrong weight or making a decimal error. D (3.3 mL/hr) might be the result if the concentration was assumed to be 10mg in 100mL.

Question 16

A vasopressin infusion is ordered to start at 0.03 units/minute. The pharmacy supplies a bag containing 50 units of vasopressin in 250 mL of NS. What is the correct initial rate for the infusion pump in mL/hr?

  1. 3.0 mL/hr
  2. 6.0 mL/hr
  3. 9.0 mL/hr (correct answer)
  4. 12.0 mL/hr
Explanation: This problem requires converting a dose from units/minute to a rate in mL/hr.
  1. Convert dose to units/hr: 0.03 units/min × 60 min/hr = 1.8 units/hr.
  2. Calculate concentration: 50 units / 250 mL = 0.2 units/mL.
  3. Calculate rate: Rate = Dose / Concentration = 1.8 units/hr / 0.2 units/mL = 9 mL/hr.
A (3.0 mL/hr) would be the rate for a dose of 0.01 units/min. B (6.0 mL/hr) would be the rate for a dose of 0.02 units/min. D (12.0 mL/hr) would be the rate for a dose of 0.04 units/min.

Question 17

An infusion pump is alarming for 'occlusion downstream'. After resolving the occlusion, the nurse notes the pump screen displays 'Volume to be infused: 150 mL' and 'Time remaining: 2 hr 30 min'.

Based on the information on the pump screen, at what rate in mL/hr is the infusion currently programmed to run?

  1. 50 mL/hr
  2. 60 mL/hr (correct answer)
  3. 75 mL/hr
  4. 100 mL/hr
Explanation: This question tests the fundamental relationship Rate = Volume / Time, requiring a conversion of the time unit.
  1. Convert time to hours: 2 hr 30 min = 2.5 hours.
  2. Calculate rate: Rate = Total Volume / Total Time = 150 mL / 2.5 hr = 60 mL/hr.
A (50 mL/hr) would be the rate if the time remaining was 3 hours. C (75 mL/hr) would be the rate if the time remaining was 2 hours. D (100 mL/hr) would be the rate if the time remaining was 1.5 hours.

Question 18

A patient's blood pressure is not responding to a norepinephrine infusion that is currently at its maximum protocol dose of 0.5 mcg/kg/min. The patient weighs 80 kg and the infusion concentration is 8 mg in 250 mL. The protocol states 'If at max norepinephrine dose and MAP < 65, notify provider and anticipate order for vasopressin.' What is the current norepinephrine infusion rate in mL/hr?

  1. 37.5 mL/hr
  2. 50.0 mL/hr
  3. 62.5 mL/hr
  4. 75.0 mL/hr (correct answer)
Explanation: The question asks for the infusion rate at the maximum dose, which requires a standard dose-to-rate calculation. The information about vasopressin is context for a decision-making scenario but not needed for the calculation.
  1. Calculate total dose in mcg/min: 0.5 mcg/kg/min × 80 kg = 40 mcg/min.
  2. Convert dose to mcg/hr: 40 mcg/min × 60 min/hr = 2400 mcg/hr.
  3. Calculate concentration: 8 mg = 8000 mcg. Concentration = 8000 mcg / 250 mL = 32 mcg/mL.
  4. Calculate rate: Rate = Dose / Concentration = 2400 mcg/hr / 32 mcg/mL = 75 mL/hr.
A (37.5 mL/hr) would be the rate for a dose of 0.25 mcg/kg/min (half the max dose). B (50.0 mL/hr) might be selected if the concentration was incorrectly calculated using 4 mg in the bag. C (62.5 mL/hr) is incorrect and does not correspond to a common calculation error.

Question 19

A patient is receiving an amiodarone maintenance infusion post-bolus. The order is for 0.5 mg/min for 18 hours. The IV bag contains 450 mg of amiodarone in 250 mL of D5W. What is the correct infusion rate in mL/hr?

  1. 12.5 mL/hr
  2. 16.7 mL/hr (correct answer)
  3. 20.8 mL/hr
  4. 33.3 mL/hr
Explanation: This is a non-weight-based calculation requiring unit conversions.
  1. Convert dose from mg/min to mg/hr: 0.5 mg/min × 60 min/hr = 30 mg/hr.
  2. Calculate concentration: 450 mg / 250 mL = 1.8 mg/mL.
  3. Calculate rate in mL/hr: Rate = Dose / Concentration = 30 mg/hr / 1.8 mg/mL ≈ 16.7 mL/hr. The 18-hour duration is information about the order's length but not needed for the rate calculation.
A (12.5 mL/hr) might result from a calculation error, possibly in the concentration. C (20.8 mL/hr) would be the rate if the concentration was 900mg in 500mL and the dose was 1mg/min. D (33.3 mL/hr) would be the correct rate for a dose of 1 mg/min with this concentration.

Question 20

A pharmacist receives an order for a dexmedetomidine infusion to run at 1.2 mcg/kg/hr. The patient weighs 180 lbs. The standard concentration is 400 mcg in 100 mL. What is the correct infusion rate in mL/hr?

  1. 12.3 mL/hr
  2. 24.5 mL/hr (correct answer)
  3. 36.0 mL/hr
  4. 54.0 mL/hr
Explanation: This question includes a common trap: the patient's weight is given in pounds (lbs) and must be converted to kilograms (kg).
  1. Convert weight: 180 lbs ÷ 2.2 lbs/kg ≈ 81.82 kg.
  2. Calculate total dose: 1.2 mcg/kg/hr × 81.82 kg ≈ 98.18 mcg/hr.
  3. Calculate concentration: 400 mcg / 100 mL = 4 mcg/mL.
  4. Calculate rate: 98.18 mcg/hr ÷ 4 mcg/mL ≈ 24.5 mL/hr.
A (12.3 mL/hr) is half the correct rate and may result from a calculation error. C (36.0 mL/hr) is incorrect. D (54.0 mL/hr) is the rate calculated if the weight in pounds (180) is incorrectly used as kilograms in the dose calculation: (1.2 mcg/kg/hr × 180 kg × 1 hr) / (4 mcg/mL) = 54 mL/hr. This is a very common mistake.