Which is better absorbed, ampicillin or amoxicillin?

Which is better absorbed, ampicillin or amoxicillin?

• A. Ampicillin
• B. Both equally
• C. Amoxicillin
• D. None are absorbed

Answer: (C)

Absorption hinges on how well a drug stays intact in the stomach and how much actually enters the bloodstream after swallowing. Amoxicillin wins here because it is more acid-stable and has higher oral bioavailability than ampicillin. In practical terms, amoxicillin typically achieves about 75–90% of the dose in the systemic circulation when given orally, while ampicillin is in the roughly 40–50% range. That means amoxicillin reaches therapeutic levels more reliably through oral dosing. If you’re giving the antibiotic by mouth, amoxicillin is the better choice for absorption; if you use IV or IM routes, absorption differences don’t apply.

Absorption hinges on how well a drug stays intact in the stomach and how much actually enters the bloodstream after swallowing. Amoxicillin wins here because it is more acid-stable and has higher oral bioavailability than ampicillin. In practical terms, amoxicillin typically achieves about 75–90% of the dose in the systemic circulation when given orally, while ampicillin is in the roughly 40–50% range. That means amoxicillin reaches therapeutic levels more reliably through oral dosing. If you’re giving the antibiotic by mouth, amoxicillin is the better choice for absorption; if you use IV or IM routes, absorption differences don’t apply.