Medical Emergencies · single question
A patient is on imipramine (TCA). After administering lidocaine with epinephrine, the patient's cardiovascular parameters increase. What is the most likely cause?
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Correct answer: B. Interaction between imipramine (TCA) and epinephrine — TCAs block NE reuptake → potentiated pressor response
✓ B) TCA + epinephrine interaction causes potentiated cardiovascular response.
Summary review: Imipramine (and all TCAs) block the norepinephrine/epinephrine reuptake transporter (NET) → more catecholamine remains in the synapse → AMPLIFIED response to exogenous epinephrine. Results: hypertension, tachycardia, arrhythmias. Clinical management: limit epinephrine to 0.04mg max in TCA patients, avoid cardiac retraction cord with epinephrine, monitor vitals. Sumatriptan (serotonin agonist for migraines) in the PDF is a different drug — its interaction is less severe, but the TCA (imipramine) interaction with epi is the classic testable one.
Summary review: Imipramine (and all TCAs) block the norepinephrine/epinephrine reuptake transporter (NET) → more catecholamine remains in the synapse → AMPLIFIED response to exogenous epinephrine. Results: hypertension, tachycardia, arrhythmias. Clinical management: limit epinephrine to 0.04mg max in TCA patients, avoid cardiac retraction cord with epinephrine, monitor vitals. Sumatriptan (serotonin agonist for migraines) in the PDF is a different drug — its interaction is less severe, but the TCA (imipramine) interaction with epi is the classic testable one.
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