Penicillin V vs Amoxicillin — MFDS Part 1 MCQ
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Correct answer: C — It has a narrower antibacterial spectrum
Option C is correct. Phenoxymethylpenicillin has a narrower antibacterial spectrum than amoxicillin; SDCEP therefore favours it as the first-choice penicillin when an antibiotic is indicated for a dento-alveolar infection. Option A reverses this relationship. Phenoxymethylpenicillin is beta-lactamase sensitive and is inactivated by penicillinase, so C is incorrect. It does not provide reliable antipseudomonal activity, excluding D. Its oral absorption is rapid but incomplete at around 60%, and food can reduce absorption slightly; by comparison, amoxicillin is approximately 70% bioavailable and its absorption is unaffected by food. Thus E is also incorrect. Amoxicillin should not be preferred routinely merely because it is better absorbed.
Reference: Scottish Dental Clinical Effectiveness Programme (SDCEP), Update to Drug Prescribing guidance now available, 2021: https://www.sdcep.org.uk/news/update-to-drug-prescribing-guidance-now-available/