Citalopram

Aka: Citalopram, Celexa, Escitalopram, Lexapro, Citalopram Overdose

1. Mechanism
   1. Selective Serotonin Reuptake Inhibitor (SSRI)
   2. Minimal effects on other Neurotransmitters
2. Pharmacokinetics
   1. Half-life: 20 to 35 hours
   2. Bioavailability: 80%
   3. Peak drug levels: 4 hours
3. Indications
   1. Major Depression
4. Preparations
   1. Citalopram (Celexa)
      1. Tablets: 10, 20 (scored), 40 (scored)
      2. Oral Solution: 10 mg/5 ml
   2. Escitalopram (Lexapro)
      1. Active isomer of racemic Citalopram
      2. Tablets: 5, 10 (scored), 20 mg (scored)
5. Dosing
   1. Citalopram (Celexa)
      1. Starting dose: 20 mg PO qd
      2. Most effective dose: 40 mg PO qd
      3. Maximum Dose: 40 mg
   2. Escitalopram (Lexapro)
      1. Starting Dose: 10 mg qd (equivalent to 40 mg Celexa)
      2. Higher dose at 20 mg is not more effective than 10 mg
6. Adverse Effects: General
   1. No increased weight gain
   2. Midway on spectrum between Anxiolytic and anxiogenic
      1. Similar to Zoloft on this spectrum
      2. Well tolerated
   3. Nausea
      1. May occur initially but is transient
      2. Consider decreasing dose to 10 mg initially
   4. Less Sexual Dysfunction than Prozac, Zoloft, Paxil
      1. Sexual Dysfunction in 10-15% of cases
      2. Similar to Luvox and Effexor in terms of this effect
      3. See Antidepressant Induced Sexual Dysfunction
7. Adverse Effects: Overdose
   1. See SSRI Overdose
   2. P450 Metabolism to di-desmethylcitalopram
      1. Di-desmethylcitalopram is cardiotoxic (inhibits cardiac Potassium and Calcium channels)
   3. Overdose presentation (esp. ingestions >600 mg)
      1. Sedation
      2. Seizures
      3. Tachycardia
      4. QT Prolongation
      5. Torsades de Pointes
      6. Metabolic Acidosis
      7. Hypokalemia
   4. Evaluation and Management
      1. See SSRI Overdose
      2. See Serotonin Syndrome
      3. See Unknown Ingestion
   5. Monitoring
      1. Asymptomatic
         1. Monitor up to 12 hours if suspected ingestion >400 mg
      2. Symptomatic or QTc Prolongation
         1. Monitor until resolution of symptoms and QTc normalization
   6. References
      1. Tomszewski (2021) Crit Dec Emerg Med 35(12): 32
8. Drug Interactions
   1. Cytochrome P450 2C19 Inhibitors
      1. Arrhythmia risk: Prolonged QT interval and Torsades de Pointes risk
      2. Most significant agents
         1. Proton Pump Inhibitors: Omeprazole, Esomeprazole
         2. Ethinyl Estradiol (Oral Contraceptives)
      3. Agents that do not appear to have significant interactions
         1. Proton Pump Inhibitors: Pantoprazole, Lansoprazole, Dexlansoprazole
      4. Precautions
         1. Limit Citalopram to 20 mg daily in those on Omeprazole, Esomeprazole, Oral Contraceptives
         2. Consider Escitalopram (Lexapro) instead which appears safe to at least 20 mg daily with these agents
      5. Resources
         1. FDA Drug Safety Notice
            1. http://www.fda.gov/Drugs/DrugSafety/ucm269086.htm
9. Resources
   1. Celexa Website (Forest Pharmaceuticals)
      1. http://www.celexa.com