Warfarin Citalopram

Citalopram (Celexa) [Antidepressant/SSRI] WARNING Closely monitor for worsening depression or emergence of suicidality, particularly in pts <24 y Uses Depression Action SSRI Dose Initial 20 mg/d, may t to 40 mg/d X in elderly hqjatic/renal insuff Caution [C, +/-] Hx of mania, Szs pts at risk for suicide Contra MAOI or w/in 14 d of MAOI use Disp Tabs, cap, soln SE Somnolence, insomnia, anxiety, xerostomia, diaphoresis, sexual dysfxn Notes May cause X Na /SIADH Interactions t Effects W/ azole antifungals, cimetidine, Li, macrolides, EtOH t effects OF BBs, carbamazepine, CNS drugs, warfarin X effects W/ carbamaz ine X effects OF phenytoin may cause fatal Rxn W/ MAOIs EMS Use caution w/ CNS depressants, may need a reduced dose concurrent EtOH... 

C19 TCAs, citalopram (partly), warfarin, tolbutamide, phenytoin, diazepam Fluoxetine, fluvoxamine, sertraline, imipramine, ketoconozole, omeprazole Rifampin... 

Clinically important, potentially hazardous interactions with aspirin, celecoxib, citalopram, etoricoxib, fluoxetine, NSAIDs, paroxetine, venlafaxine, warfarin... 

Amitriptyline, barbiturates, chlorproguanil, citalopram, clomipramine, clozapine, cyclophosphamide, diazepam, hexobarbital, imipramine, pentamidine, phenobarbital, phenytoin, propranolol, quinine, (S)- and (Jf)-warfarin, zidovudine... 

SSRI drug interactions The SSRls are inhibitors of hepatic cytochrome P450 isozymes, an action that has led to increased activity of other drugs including tricyclic antidepressants and warfarin. Huvoxamine inhibits the metabolism of cisapride, astemizole, and terfena-dine, and the resultant cardiotoxicity has led to the withdrawal of the latter two thugs (see Table 30-3). Citalopram causes fewer drug interactions than other SSRls. 

None of the other SSRIs studied (citalopram, fluoxetine, paroxetine) have been shown to alter the pharmacokinetics of warfarin, and neither fluoxetine nor paroxetine increased the prothrombin time. However, citalopram and sertraline caused a less than 10% increase in prothrombin time, and a few patients taking paroxetine with warfarin had bleeds. However, in general, these effects would generally not be expected to be clinically relevant. Nevertheless, because SSRIs alone can rarely cause bleeding, some predict that this may result in additive effects with cou-marins and indanediones, and recommend caution with all SSRIs. Note that there are case reports of interactions with warfarin for many of the SSRIs (citalopram, fluoxetine, paroxetine, sertraline). 

PriskomM, SidhuJS, Larsen F, Davis JD, KhanAZ,RolanPE. Investigation of multiple dose citalopram on the pl rmacokinetics and pharmacocfynamics of racemic warfarin. BrJ Clin Pharmacol (1997) 44,199-202. 

---