Dextromethorphan SSRIs

Many commonly used medications also contain substances that are eliminated by the MAOIs and must not be taken by these patients. The list of medications to be avoided inclndes the narcotic pain reliever meperidine (Demerol), and many over-the-connter cold remedies containing dextromethorphan or pseudoephedrine. Finally, patients taking MAOIs must also avoid medications that elevate serotonin levels. This inclndes certain appetite snppressants and antidepressants including the SSRIs, venlafaxine, duloxetine, mirtazapine, nefazodone, and trazodone. Medications that interact with the MAOIs cannot be taken until at least 2 weeks after the MAOI has been stopped. 

Uses Obesity Action Blocks uptake of norepinephrine, serotonin, dopamine Dose 10 mg/d PO, may to 5 mg after 4 wk Caution [C, -] w/ SSRIs, Li, dextromethorphan, opioids Contra MAOI w/in 14 d, uncontrolled HTN, arrhythmias Disp Caps SE HA, insomnia, xerostomia, constipation, rhinitis, tach, HTN Interactions T Risk of serotonin synd W/ dextromethorphan, ergots, fentanyl, Li, meperidine, MAOIs, naratriptan, pentazocine, rizatriptan, sumatriptan, SSRIs, tryptophan, zolmitriptan, St. John s wort effects W/ cimetidine, erythromycin, ketoconazole T CNS depression W/ EtOH EMS Use fentanyl w/ caution, may T risk of serotonin synd concurrent EtOH use can T CNS depression OD May cause tach, HTN, diaphoresis, HA, fever, agitation, muscle tremors, and Szs symptomatic and supportive... 

Dmg-induced serotonin syndrome is generally mild and resolves when the offending drugs are stopped. However, it can be severe and deaths have occurred. A large number of drugs have been implicated including tricyclic antidepressants, monoamine oxidase inhibitors (MAOIs), selective serotonin re-uptake inhibitors (SSRIs), pethidine, lithium, and dextromethorphan. The most severe type of reaction has occurred with the combination of selective serotonin re-uptake inhibitors and monoamine oxidase inhibitors. Both non-selective MAOIs such as phenelzine and selective MAOIs such as moclobemide and selegiline have been implicated. 

Fenfluramine Dextromethorphan Meperidine Methylene dioxymethamphetamine Meta-chlorophenylpiperazine (mCPP) Trazodone (mCPP) Selegiline Nefazodone Trazodone Pethidine Tramadol Mirtazapine TCA medications Venlafaxine SSRI agents... 

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,... 

In ALS, emotional lability or pseudobulbar affect can limit social interactions and quality of life. While there are no currently FDA approved therapies for pseudobulbar affect in ALS, SSRIs, tricylic antidepressants and dopaminergic therapy can be beneficial (Gordon and Mitsumoto, 2006). One randomized controlled trial showed that a combination of dextromethorphan and quinidine reduced emotional lability and improved quality of life in ALS (Brooks et al., 2004). 

Pseudobulbar affect SSRI antidepressants 20-100 mg QD Tricyclic antidepressants 20-100 mg QHS Mirtazapine 15-30 mg QHS Venlafaxine 37.5-75 mg BID-TID Dextromethorphan/quinidine 30mg/30mg BID Lithium carbonate 300 mg QD-TID... 

In 31 healthy men and women (mean age 28 years) the ability of four SSRIs (fluoxetine, fluvoxamine, paroxetine, and sertraline) to inhibit CYP2D6 activity was assessed in vivo, as judged by the dextromethorphan test (63). All were extensive metabolizers of dextromethorphan. After 8 days treatment at therapeutic doses, four of eight paroxetine-treated and five of eight fluoxetine-treated subjects had become poor metabolizers, presumably because of the inhibitory effect of the two SSRIs... 

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

Clinically important, potentially hazardous interactions with aminophylline, ciprofloxacin, dextromethorphan, entacapone, fluoxetine, fluvoxamine, MAO inhibitors, meperidine, pethidine, pseudoephedrine, SSRIs... 

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." ... 

Drug interactions serotonin syndrome includes diaphoresis, rigidity, myoclonus, hyperthermia, ANS instability, and seizures. Has been reported for SSRIs when used with MAOIs, TCAs, meperidine, and dextromethorphan. 

Because sibutramine inhibits serotonin uptake, and because the serious serotonin syndrome has been seen when serotonergic drugs were taken with SSRIs, the manufacturers say that sibutramine should not be taken with any serotonergic drugs. They name dextromethorphan, dihydroergot-amine, fentanyl, pentazocine, pethidine (meperidine), SSRIs, sumatriptan, and tryptophan. Possible cases have been reported for sibutramine and SSMs , (below).The US manufacturers also include lithium in their list. Note that this list is not exhaustive (see MAOIs under (d) above) and a case of the serotonin syndrome has been seen when venla-faxine was given with sibutramine. ... 

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. ... 

These seem to be, so far, the only reports of the serotonin syndrome being attributed to an interaetion between an SSRI and dextromethorphan. However, it has been suggested that the ineidenee of mild serotonin excess (as seen in with citalopram) may be more eommon than is known. The general importance of this apparent interaetion is therefore very uncertain. The SSRIs are now very widely prescribed and dextromethorphan is a rel-... 

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