Which drug is known to have significant interactions when combined with MAOIs?

Dextromethorphan is known to have significant interactions when combined with monoamine oxidase inhibitors (MAOIs), primarily due to the pharmacological effects of both substances. Dextromethorphan is a common cough suppressant that acts on the central nervous system, and when taken with MAOIs, it can lead to increased levels of serotonin, potentially causing serotonin syndrome— a serious condition characterized by symptoms like agitation, confusion, rapid heart rate, increased body temperature, and muscle rigidity. This interaction underscores the necessity for caution when prescribing dextromethorphan to patients who are also taking MAOIs.

The other medications listed do not typically produce such severe interactions with MAOIs. Ibuprofen is a nonsteroidal anti-inflammatory drug (NSAID) that mainly affects pathways related to pain and inflammation rather than neurotransmitter systems. Hydrochlorothiazide is a diuretic used to manage hypertension and does not interact significantly with MAOIs. Metformin, commonly used for managing type 2 diabetes, also does not have well-documented interactions with MAOIs, making dextromethorphan the primary concern in this context.