A physician orders 500 mg of erythromycin orally. You have 250 mg capsules on hand. How many capsules should you administer?

A physician orders 500 mg of erythromycin orally. You have 250 mg capsules on hand. How many capsules should you administer?

• A. 3 capsules
• B. 4 capsules
• C. 2 capsules
• D. 1 capsule

Answer: (C)

Start with how much is needed versus how much each capsule provides. The prescription calls for 500 mg, and each erythromycin capsule is 250 mg. Divide the total dose by the amount per capsule: 500 mg ÷ 250 mg per capsule = 2. So you should administer two capsules to reach the prescribed 500 mg. Giving one capsule would be only 250 mg, while three capsules would be 750 mg, which is more than ordered. This straightforward division is the reliable way to match the prescribed dose when you have a fixed capsule strength. Always double-check the medication and patient factors, but with these strengths, two capsules is the correct amount.

Start with how much is needed versus how much each capsule provides. The prescription calls for 500 mg, and each erythromycin capsule is 250 mg. Divide the total dose by the amount per capsule: 500 mg ÷ 250 mg per capsule = 2. So you should administer two capsules to reach the prescribed 500 mg. Giving one capsule would be only 250 mg, while three capsules would be 750 mg, which is more than ordered. This straightforward division is the reliable way to match the prescribed dose when you have a fixed capsule strength. Always double-check the medication and patient factors, but with these strengths, two capsules is the correct amount.