What can happen when TCAs and MAOIs are combined?

What can happen when TCAs and MAOIs are combined?

• A. Increased norepinephrine causing a hypertensive crisis
• B. Serotonin syndrome
• C. QT prolongation
• D. Seizures

Answer: (A)

When TCAs and MAOIs are combined, monoamine levels rise far more than with either drug alone, especially norepinephrine. MAOIs prevent the breakdown of norepinephrine, serotonin, and dopamine, while TCAs block the reuptake of norepinephrine and serotonin, increasing their concentrations in the synapse. The net result is a powerful surge of norepinephrine activating alpha-adrenergic receptors, which can trigger a hypertensive crisis with sudden, dangerous spikes in blood pressure, headaches, sweating, tachycardia, and potential risk for stroke or heart problems. Serotonin syndrome is a possible concern with MAOIs and other serotonergic agents, but the most characteristic and immediate risk with this combination is hypertensive crisis due to norepinephrine excess. QT prolongation and seizures can occur with TCAs in other contexts, but they are not the hallmark interaction here.

When TCAs and MAOIs are combined, monoamine levels rise far more than with either drug alone, especially norepinephrine. MAOIs prevent the breakdown of norepinephrine, serotonin, and dopamine, while TCAs block the reuptake of norepinephrine and serotonin, increasing their concentrations in the synapse. The net result is a powerful surge of norepinephrine activating alpha-adrenergic receptors, which can trigger a hypertensive crisis with sudden, dangerous spikes in blood pressure, headaches, sweating, tachycardia, and potential risk for stroke or heart problems. Serotonin syndrome is a possible concern with MAOIs and other serotonergic agents, but the most characteristic and immediate risk with this combination is hypertensive crisis due to norepinephrine excess. QT prolongation and seizures can occur with TCAs in other contexts, but they are not the hallmark interaction here.