Which statement about tricyclic antidepressants in patients receiving general anesthesia is TRUE?

Which statement about tricyclic antidepressants in patients receiving general anesthesia is TRUE?

• A. They should be discontinued two weeks before elective operations
• B. They may decrease the requirement for volatile anesthetics (MAC)
• C. Meperidine may produce hyperpyrexia in patients taking tricyclic antidepressants
• D. They may exaggerate the response to ephedrine

Answer: (D)

Tricyclic antidepressants blur the line between normal adrenergic signaling and anesthesia by blocking the reuptake of norepinephrine. That means more NE stays in the synapse, amplifying sympathetic effects. Ephedrine works partly by releasing stored norepinephrine, in addition to its direct receptor stimulation. When a patient is on a TCA, the combination of ephedrine's NE release with the drug’s reuptake blockade leads to a much larger than usual surge in norepinephrine—producing an exaggerated pressor response with marked hypertension and tachycardia. This interaction is well described and clinically important, making that statement true. The other options are less consistently observed or not as clinically significant. Stopping TCAs two weeks before surgery isn’t routinely required and can cause instability; the idea that TCAs reliably decrease the MAC of volatile anesthetics isn’t a dependable effect; and while there are some cautions about combining analgesics like meperidine with TCAs, the most consistently noted and important perioperative interaction is the exaggerated response to indirect-acting vasopressors such as ephedrine.

Tricyclic antidepressants blur the line between normal adrenergic signaling and anesthesia by blocking the reuptake of norepinephrine. That means more NE stays in the synapse, amplifying sympathetic effects. Ephedrine works partly by releasing stored norepinephrine, in addition to its direct receptor stimulation. When a patient is on a TCA, the combination of ephedrine's NE release with the drug’s reuptake blockade leads to a much larger than usual surge in norepinephrine—producing an exaggerated pressor response with marked hypertension and tachycardia. This interaction is well described and clinically important, making that statement true.

The other options are less consistently observed or not as clinically significant. Stopping TCAs two weeks before surgery isn’t routinely required and can cause instability; the idea that TCAs reliably decrease the MAC of volatile anesthetics isn’t a dependable effect; and while there are some cautions about combining analgesics like meperidine with TCAs, the most consistently noted and important perioperative interaction is the exaggerated response to indirect-acting vasopressors such as ephedrine.