Venlafaxineinteractions

7.1 Drugs Having

Clinically Important Interactions with Effexor XR Table 15: Clinically Important Drug Interactions with Effexor XR Monoamine Oxidase Inhibitors (MAOI) Clinical Impact The concomitant use of SNRIs, including Effexor XR, with MAOIs increases the risk of serotonin syndrome. Intervention Concomitant use of Effexor XR is contraindicated in patients taking MAOIs, including MAOIs such as linezolid or intravenous methylene blue. Other Serotonergic Drugs Clinical Impact Concomitant use of Effexor XR with other serotonergic drugs (including other SNRIs, SSRIs, triptans, tricyclic antidepressants, opioids, lithium, buspirone, amphetamines, tryptophan, and St. John's Wort) increases the risk of serotonin syndrome. Intervention Monitor for symptoms of serotonin syndrome when Effexor XR is used concomitantly with other drugs that may affect the serotonergic neurotransmitter systems. If serotonin syndrome occurs, consider discontinuation of Effexor XR and/or concomitant serotonergic drugs. Drugs that Interfere with Hemostasis Clinical Impact Concomitant use of Effexor XR with an antiplatelet or anticoagulant drug may potentiate the risk of bleeding. This may be due to the effect of Effexor XR on the release of serotonin by platelets. Intervention Closely monitor for bleeding for patients receiving an antiplatelet or anticoagulant drug when Effexor XR is initiated or discontinued. Effect of CYP3A Inhibitors Clinical Impact Concomitant use of a CYP3A inhibitor increases the C max and AUC of venlafaxine and O-desmethylvenlafaxine (ODV), which may increase the risk of toxicity of Effexor XR. Intervention Consider reducing the dose of Effexor XR. CYP2D6 Substrates Clinical Impact Concomitant use of Effexor XR increases C max and AUC of a CYP2D6 substrate, which may increase the risk of toxicity of the CYP2D6 substrate. Intervention Consider reduction in dose of concomitant CYP2D6 substrates.

7.2 Other Drug

Interactions with Effexor XR Central Nervous System (CNS)-Active Drugs The risk of using venlafaxine concomitantly with other CNS-active drugs (including alcohol) has not been systematically evaluated. Consequently, caution is advised when Effexor XR is taken concomitantly in combination with other CNS-active drugs. Weight Loss Agents Concomitant use of Effexor XR and weight loss agents is not recommended. The safety and efficacy of venlafaxine therapy in combination with weight loss agents, including phentermine, have not been established. Effexor XR is not indicated for weight loss alone or in combination with other products. Laboratory Test Interference False-positive urine immunoassay screening tests for phencyclidine (PCP) and amphetamine have been reported in patients taking venlafaxine due to lack of specificity of the screening tests. False-positive test results may be expected for several days following discontinuation of venlafaxine therapy. Confirmatory tests, such as gas chromatography/mass spectrometry, will distinguish venlafaxine from PCP and amphetamine.