Med Math: Drop Factors Question #2


Erythromycin 200 mg in 250 mL D5W to infuse over 1 hour. Drop factor is 15 gtt/mL. _____


  1. 13 gtt/min
    • Rationale:
  2. 42 gtt/min
    • Rationale:
  3. 83 gtt/min
    • Rationale:
  4. 63 gtt/min
    • Rationale:



Erythromycin is ordered in 200 mg. This is extra information and not needed to solve the problem.The D5W is also extra information and not needed to solve the problem. You would need to know how much volume you needed in order to solve. The volume is 250 ml over 1 hour. The hour is converted to minutes. There is a simple formula below for calculating the drop factor. The final answer should have gtt/min within.


—– x gtt


250 mL/60 min x 15 gtt factor/1 = 63 gtt/min

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