GroovyGwen Posted December 13, 2007 Share Posted December 13, 2007 Moderate Drug-Drug Interaction: Effexor XR (venlafaxine) and Robitussin-DM (dextromethorphan-guaifenesin) -------------------------------------------------------------------------------- * The interaction is due to dextromethorphan which is a component of venlafaxine -------------------------------------------------------------------------------- MONITOR CLOSELY: Concomitant use of agents with serotonergic activity such as serotonin reuptake inhibitors, monoamine oxidase inhibitors, tricyclic antidepressants, 5-HT1 receptor agonists, ergot alkaloids, lithium, St. John's wort, phenylpiperidine opioids, dextromethorphan, and 5-hydroxytryptophan may potentiate the risk of serotonin syndrome, which is a rare but serious and potentially fatal condition thought to result from hyperstimulation of brainstem 5-HT1A receptors. MANAGEMENT: In general, the concomitant use of multiple serotonergic agents should be avoided if possible, or otherwise approached with caution if potential benefit is deemed to outweigh the risk. Close monitoring is recommended for signs and symptoms of excessive serotonergic activity such as CNS irritability, altered consciousness, confusion, myoclonus, ataxia, abdominal cramping, hyperpyrexia, shivering, pupillary dilation, diaphoresis, hypertension, and tachycardia. Particular caution is advised when increasing the dosages of these agents. The potential risk of serotonin syndrome should be considered even when administering one serotonergic agent following discontinuation of another, as some agents may demonstrate a prolonged elimination half-life. For example, a 5-week washout period is recommended following use of fluoxetine before administering another serotonergic agent. Wait - WHAT???? Dextromethorphan is in Effexor and it's the same stuff that's in Robitussin????? Alright you pharmageeks - explain this please!!! Link to comment Share on other sites More sharing options...
null0trooper Posted December 13, 2007 Share Posted December 13, 2007 Moderate Drug-Drug Interaction: Effexor XR (venlafaxine) and Robitussin-DM (dextromethorphan-guaifenesin) -------------------------------------------------------------------------------- * The interaction is due to dextromethorphan which is a component of venlafaxine -------------------------------------------------------------------------------- hahaha ... BULLSHIT In the real world, Effexor XR "Capsules contain venlafaxine hydrochloride equivalent to 37.5 mg, 75 mg, or 150 mg venlafaxine. Inactive ingredients consist of cellulose, ethylcellulose, gelatin, hypromellose, iron oxide, and titanium dioxide." (RxList) venlafaxine interacts with dextromethorphan by inhibiting the CYP 2D6 (iso)enzyme J Clinical Pharm, but not to the extent that Prozac does (and by extension I'd guess not to the extent that Wellbutrin, a competitive 2D6 inhibitor does.) You'll still want to reduce your usual dose - at least by half, but this is really a good "ask your pharmacist" item. Link to comment Share on other sites More sharing options...
GroovyGwen Posted December 13, 2007 Author Share Posted December 13, 2007 See? THIS is why this site, and Null specifically too now, rocks. Thanks! Link to comment Share on other sites More sharing options...
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