Drug Interactions between Synalgos-DC and tedizolid

MONITOR: The concurrent use of tedizolid with agents that have serotonergic activity including serotonin reuptake inhibitors, monoamine oxidase inhibitors (MAOIs), tricyclic antidepressants, 5-HT1 receptor agonists, ergot alkaloids, cyclobenzaprine, lithium, St. John's wort, phenylpiperidine opioids, dextromethorphan, and tryptophan may elevate the risk of developing serotonin syndrome. The proposed mechanism is tedizolid-mediated non-selective and reversible inhibition of monoamine oxidase (MAO), with more potent inhibition of MAO-A than linezolid in vitro. In a retrospective cohort study from January 2015 to July 2023 of 479 adult patients receiving tedizolid, 62% (297/479) received concomitant serotonergic agents, but suspected serotonin syndrome requiring tedizolid discontinuation was found to be rare, occurring in only 0.4% (2/479) of cases. Symptoms of serotonin syndrome may include mental status changes such as irritability, altered consciousness, confusion, hallucination, and coma; autonomic dysfunction such as tachycardia, hyperthermia, diaphoresis, shivering, unstable blood pressure, and mydriasis; neuromuscular abnormalities such as hyperreflexia, myoclonus, tremor, rigidity, and ataxia; and gastrointestinal symptoms such as abdominal cramping, nausea, vomiting, and diarrhea.

MANAGEMENT: Caution and closer monitoring for serotonin syndrome are recommended during concomitant treatment with tedizolid and serotonergic agents, especially during dose escalations, and patients should be instructed to notify their healthcare provider if they experience symptoms of serotonin syndrome. Due to variability and occasionally prolonged half-lives of these coadministered agents, consulting individual product labeling for specific guidance is advised. If serotonin syndrome is suspected, discontinuation of therapy or dose reductions should be considered depending on the severity of the symptoms, and supportive care should be provided. Moderately ill patients may benefit from serotonin antagonists like cyproheptadine or chlorpromazine. Severe cases require consultation with a toxicologist and may need sedation, neuromuscular paralysis, intubation, and mechanical ventilation.

One study has reported that coadministration of caffeine and aspirin lead to a 25% increase in the rate of appearance and 17% increase in maximum concentration of salicylate in the plasma. A significantly higher area under the plasma concentration time curve of salicylate was also reported when both drugs were administered together. The exact mechanism of this interaction has not been specified. Physicians and patients should be aware that coadministration of aspirin and caffeine may lead to higher salicylate levels faster.