III. Mechanism

IV. Pharmacokinetics

  1. Citalopram
    1. Half-Life: 20 to 35 hours
    2. Bioavailability: 80%
    3. Peak drug levels: 4 hours
  2. Escitalopram
    1. Half-Life: 27-33 hours
    2. Bioavailability: 80%
    3. Peak drug levels: 5 hours

V. Safety

  1. Pregnancy Category C
  2. Avoid in Lactation

VI. 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)

VII. Dosing

  1. Citalopram (Celexa)
    1. Starting dose: 20 mg orally daily
    2. Most effective dose: 40 mg orally daily
    3. Maximum Dose: 40 mg
      1. Maximum dose 20 mg in hepatic Impairment or concurrent use of Cytochrome P450 2C19 Inhibitors (see below)
  2. Escitalopram (Lexapro)
    1. Starting Dose: 10 mg daily (equivalent to 40 mg Celexa)
    2. Higher dose at 20 mg is not more effective than 10 mg
      1. Maximum dose 10 mg in hepatic Impairment or use of Cytochrome P450 2C19 Inhibitors (see below)

VIII. 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
  5. Arrhythmia risk
    1. Prolonged QTc Interval and Torsades de Pointes risk
    2. Avoid in Prolonged QTc (e.g. congenital Prolonged QTc) or combined with other causes of Drug-Induced QTc Prolongation
    3. Monitor and correct for Electrolyte abnormalities (e.g. Hypokalemia, Hypomagnesemia) if risks

IX. 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. QTc 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
    4. Correct Electrolyte abnormalities (e.g. Hypokalemia, Hypomagnesemia)
  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

X. Drug Interactions

  1. Avoid with MAO Inhibitors or Tryptophan
  2. Cytochrome P450 2C19 Inhibitors (or poor 2C19 metabolizers)
    1. Arrhythmia risk
      1. Prolonged QTc Interval and Torsades de Pointes risk
      2. Avoid combining with other medication causes of Drug-Induced QTc Prolongation
    2. Most significant agents
      1. Proton Pump Inhibitors: Omeprazole, Esomeprazole, Cimetidine
      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

XII. References

  1. (2023) Med Lett Drugs Ther 62(1592): 25-32
  2. Olson (2020) Clinical Pharmacology, Medmaster Miami, p. 38-9
  3. Hamilton (2020) Tarascon Pocket Pharmacopoeia

Images: Related links to external sites (from Bing)

Related Studies

Cost: Medications

citalopram (on 12/21/2022 at Medicaid.Gov Survey of pharmacy drug pricing)
CITALOPRAM HBR 10 MG TABLET Generic $0.03 each
CITALOPRAM HBR 10 MG/5 ML SOLN Generic $0.24 per ml
CITALOPRAM HBR 20 MG TABLET Generic $0.03 each
CITALOPRAM HBR 40 MG TABLET Generic $0.04 each
escitalopram (on 12/21/2022 at Medicaid.Gov Survey of pharmacy drug pricing)
ESCITALOPRAM 10 MG TABLET Generic $0.05 each
ESCITALOPRAM 20 MG TABLET Generic $0.08 each
ESCITALOPRAM 5 MG TABLET Generic $0.04 each
ESCITALOPRAM OXALATE 5 MG/5 ML Generic $0.20 per ml
lexapro (on 1/14/2022 at Medicaid.Gov Survey of pharmacy drug pricing)
LEXAPRO 10 MG TABLET Generic $0.05 each
LEXAPRO 20 MG TABLET Generic $0.08 each
LEXAPRO 5 MG TABLET Generic $0.04 each