Serotonin syndrome dextromethorphan causing

The drugs that can cause a serotonin syndrome when they are combined with SSRIs include monoamine oxidase inhibitors (including reversible inhibitors of monoamine oxidase types A and B), dextromethorphan,... 

Dextromethorphan Some SSRIs inhibit the metabolism of dextromethorphan visual hallucinations have occurred it may cause serotonin syndrome... 

The risk of serotonin syndrome may be increased shortly after dosage increases of SSRIs or when drug interactions increase serotonin activity. Concomitant or proximal use of SSRIs, tricyclic antidepressants, or monoamine oxidase inhibitors may cause serotonin syndrome. Further, the addition of certain drugs, such as tryptophan, dextromethorphan, cocaine, or sympathomimetics, to SSRI therapy may increase the risk of developing serotonin syndrome." ... 

Four patients died after taking moclobemide and ecstasy (MDMA, methylenedioxymethamfetamine). The clinical evidence is limited, but in each case the forensic pathologist concluded that the cause of death was the combined use of these drugs. It was suggested that what happened is consistent with the serotonin syndrome, although the evidence is fairly slim. Two patients had taken maximum therapeutic doses and two moderate overdoses of moclobemide. Note that moclobemide had not been prescribed to any of them. Post-mortem analysis also found the presence of dextromethorphan in one patient, which was thought to have contributed, see also MAOIs or RIMAs -i- Dextromethorphan , p.ll34. 

Not understood. The symptoms that developed with eitalopram or paroxetine and dextromethorphan were attributed by the authors of the reports to the serotonin syndrome, caused by the additive effeets of the SSRIs and dextromethorphan on serotonin transmission. It has also been suggested that paroxetine inhibited the cytochrome P450 isoenzyme CYP2D6, by which dextromethorphan is metabolised, resulting in increased dextromethorphan levels. Fluoxetine also inhibits CYP2D6. ... 

Concomitant use of monoamine oxidase inhibitors has caused toxicity leading to coma and death. There are serious life-threatening serotonergic syndrome interactions between dextromethorphan and serotonin reuptake inhibitors. Alcohol and other CNS depressant drugs should be avoided when taking dextromethorphan. 

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