Drugs affecting or metabolized by hepatic microsomal enzymes: Inhibitors or inducers of cytochrome P-450 (CYP) 3A4 (e.g., carbamazepine, ketoconazole, ritonavir, triazolam) and 2C19 isoenzymes: clinically important pharmacokinetic interaction unlikely since escitalopram is metabolized by multiple enzyme systems.
Substrates of CYP2D6 isoenzyme (e.g., desipramine, metoprolol): potential pharmacokinetic (increased peak plasma concentrations and AUC of the substrate) interactions. Use with caution.
Drugs affecting hemostasis: Pharmacokinetics of warfarin were not affected by racemic citalopram; however, prothrombin time increased by 5%. The effects of escitalopram have not been evaluated, and the clinical importance of this interaction is unknown.
Altered anticoagulant effects, including increased bleeding, have been reported when SSRIs or selective serotonin- and norepinephrine-reuptake inhibitor (SNRIs) were concurrently administered with warfarin or other anticoagulants.
Antipsychotic agents and other dopamine antagonists: Potential pharmacologic interaction (potentially serious, sometimes fatal serotonin syndrome or NMS-like reactions) if used concurrently with antipsychotic agents or other dopamine antagonists. If signs and symptoms of serotonin syndrome or NMS occur, immediately discontinue treatment with escitalopram and any concurrently administered antidopaminergic or serotonergic agents and initiate supportive and symptomatic treatment.
5-HT1 Receptor agonists (Triptans): Potential pharmacologic interaction (potentially serious, sometimes fatal serotonin syndrome or NMS-like reactions) if used concurrently with 5-HT1 Receptor agonists (e.g., almotriptan, eletriptan, frovatriptan, naratriptan, rzatriptan, sumatriptan, zolmitriptan). If concomitant use is clinically warranted, the patient should be observed carefully, particularly during treatment initiation, when dosage is increased, or when another serotonergic agent is initiated.
Monoamine oxidase inhibitors: Isoniazid: Potential pharmacologic interaction (potentially serious serotonin syndrome) when isoniazid, an antituberculosis agent that appears to have some MAO-inhibiting activity, is used concomitantly with escitalopram.
Linezolid: Linezolid, an anti-infective agent that is also a reversible MAO inhibitor, has been associated with drug interactions resulting in serotonin syndrome, including some associated with SSRIs. Because of this potential risk, linezolid generally should not be used in patients receiving escitalopram. Treatment with escitalopram should not be initiated in a patient receiving linezolid; when necessary, escitalopram may be started 24 hours after the last linezolid dose.
Alcohol: Concomitant use not recommended.
Cimetidine: Potential pharmacokinetic interaction (increased AUC and peak plasma concentrations of citalopram have been observed).
Citalopram: Potential pharmacologic interaction (potentially serious, sometimes fatal serotonin syndrome or NMS-like reactions).
CNS-active drugs: Potential pharmacologic interaction when given with other centrally acting drugs; use concomitantly with caution.
Digoxin: Pharmacokinetic interaction unlikely based on studies with racemic citalopram.
Lithium: Escitalopram is recommended that plasma lithium concentrations be monitored in patients concurrently receiving escitalopram and that lithium dosage be adjusted accordingly.
Ritonavir: Combined administration of a single 600-mg dose of ritonavir, a CYP3A4 substrate and potent inhibitor of CYP3A4, and escitalopram 20mg did not substantially affect the pharmacokinetics of either drug.
Sibutramine: Potential pharmacologic interaction (potentially serious, sometimes fatal serotonin syndrome or NMS-like reactions).
Theophylline: Pharmacokinetics of theophylline were not affected by racemic citalopram.