Erythromycin 1000 mg per day divided into two equal doses is prescribed IV, each dose over 30 minutes. With erythromycin 500 mg/100 mL, at what rate should the nurse infuse each dose (mL/hr)?

Erythromycin 1000 mg per day divided into two equal doses is prescribed IV, each dose over 30 minutes. With erythromycin 500 mg/100 mL, at what rate should the nurse infuse each dose (mL/hr)?

• A. 100 mL/hr
• B. 200 mL/hr
• C. 300 mL/hr
• D. 400 mL/hr

Answer: (B)

Calculate the infusion rate by converting the dose to the volume from the solution’s concentration, then divide that volume by the infusion time. Each dose is 1000 mg per day divided into two equal doses, so 500 mg per dose. The solution is 500 mg/100 mL, which means 500 mg requires 100 mL. Infusing this 100 mL over 30 minutes (0.5 hours) gives an rate of 100 mL ÷ 0.5 h = 200 mL/hr. Therefore, administer at 200 mL/hr for each 100 mL dose.

Calculate the infusion rate by converting the dose to the volume from the solution’s concentration, then divide that volume by the infusion time.

Each dose is 1000 mg per day divided into two equal doses, so 500 mg per dose. The solution is 500 mg/100 mL, which means 500 mg requires 100 mL. Infusing this 100 mL over 30 minutes (0.5 hours) gives an rate of 100 mL ÷ 0.5 h = 200 mL/hr.

Therefore, administer at 200 mL/hr for each 100 mL dose.