Beware the Serotonin Syndrome with Linezolid

Linezolid is the first oxazolidinone antimicrobial to be approved for use in the U.S. Its unique mechanism of action and its high oral bioavailability have made it useful for treating a variety of infections caused by gram-positive bacteria. Linezolid inhibits both the A and B subtypes of monoamine oxidase (MAO), enzymes that metabolize the neurotransmitters epinephrine, norepinephrine, serotonin, and dopamine. MAO inhibition can lead to increases in serotonin levels and present clinically as the serotonin syndrome, which consists of cognitive or behavioral changes, autonomic instability, and neuromuscular excitability (commonly manifested as spontaneous clonus). Although by itself, linezolid is too weak an MAO inhibitor to lead to the sero…