PTCB Certified Pharmacy Technician (PTCE)Order Entry and ProcessingHard
A pharmacy receives an order for "Dopamine 400 mg in 250 mL D5W to infuse at 5 mcg/kg/min for a 70 kg patient." The pharmacy technician needs to calculate the infusion rate in mL/hr. What is the correct infusion rate?
- A21 mL/hr
- B31.5 mL/hr
- C13.13 mL/hr
- D10.5 mL/hr
Show answer & explanationAnswer & explanation
Correct answer: C. 13.13 mL/hr
First, calculate the total mg/hr: 5 mcg/kg/min * 70 kg * 60 min/hr = 21,000 mcg/hr = 21 mg/hr. Next, calculate mL/hr using the concentration: (250 mL / 400 mg) = 0.625 mL/mg. So, 0.625 mL/mg * 21 mg/hr = 13.125 mL/hr. Rounded appropriately, this is 13.13 mL/hr.
Why the other options are wrong
- A. Incorrect, likely a miscalculation in concentration or conversion.
- B. Incorrect, overestimation of the rate.
- D. Incorrect calculation, possibly missing a conversion factor.
IV Drip Rate Calculation (mcg/kg/min)
A complex calculation involving patient weight, drug concentration, desired dose, and time to determine the appropriate infusion rate in mL/hr for IV medications.
- Units must be consistent (e.g., mcg to mg, min to hr).
- Formula: (Dose x Weight x Time) / Concentration.
- Pay close attention to all conversion factors.
Memory trick: Drip Rate: Dose, Weight, Time, Concentration – Get It Right!