MAOI Drug Interaction — NDEB AFK MCQ

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HardPharmacologyMAOI Drug InteractionNDEB AFK

A patient taking phenelzine (a monoamine oxidase inhibitor) for depression presents for dental treatment. Which drug interaction is of most concern?

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Correct answer: B — Epinephrine in local anaesthetic causing hypertensive crisis

Monoamine oxidase inhibitors (MAOIs) such as phenelzine prevent the breakdown of catecholamines (norepinephrine, epinephrine, dopamine). Exogenous administration of sympathomimetic amines (including epinephrine in dental local anaesthetics) can cause an exaggerated hypertensive response. Current evidence suggests that the small amounts of epinephrine in dental local anaesthetics (1:100,000 or 1:200,000) can be used cautiously with aspiration and limited to 2 cartridges, but indirect-acting sympathomimetics should be avoided.

Reference: Malamed – Handbook of Local Anesthesia, 7th ed., 2020