II. Class

III. Mechanism

  1. Dopamine, Serotonin, histamine and adrenergic Antagonist
  2. Potent alpha-1 Adrenergic ReceptorAntagonist (risk of Hypotension)
  3. Weak Antagonist at Dopamine (D2), muscarinic (M1) and Serotonin (5HT-1A) with risk of sedation

IV. Indications

V. Dosing

  1. Available in both immediate release and sustained release formulations
  2. Adults
    1. Initial: 25 mg PO bid-tid
    2. Increase in 25-50 mg/day increments
    3. Target: 300-400 mg/day divided bid-tid
    4. Maximum dose: 750 mg/day
  3. Elderly
    1. Initial dose: 12.5 mg PO qhs
    2. Titrate up every few days (caution due to sedation)

VI. Pharmacokinetics

  1. Lipophilic
  2. Large volume of distribution (10 L/kg +/-4 L/kg)
  3. Plasma Protein binding: 83%
  4. Not dialyzable
  5. Half-Life: 6 hours
  6. Peak Levels: 2-3 hours
  7. Metabolism: CYP 3A4

VII. Adverse Effects: General

VIII. Adverse Effects: Overdose

IX. Drug Interactions

  1. Increase Antipsychotic levels (toxicity risk): Monitor for toxicity
    1. Clarithromycin
    2. Erythromycin
    3. Grapefruit juice
    4. Fluconazole
    5. Itraconazole
    6. Ketoconazole
    7. Quinidine
  2. Decrease Antipsychotic levels (lower efficacy)
    1. Barbiturates
    2. Carbamazepine
    3. Phenytoin
    4. Rifampin
    5. Theophylline
  3. Other effects
    1. Avoid concurrent use of other medications prolonging QT Interval
      1. See Prolonged QT Interval due to Medication

X. Monitoring

  1. See Quetiapine Overdose
  2. See Antipsychotic
  3. Screen for Cataract formation every 6 months
  4. Consider EKG, Electrolyte and Magnesium monitoring due to QT Interval prolongation risk

XI. Pharmacokinetics

  1. Metabolized by Cytochrome P450 3A4

XII. References

  1. Otter and Tomaszewski (2018) Crit Dec Emerg Med 32(8): 32

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Cost: Medications

quetiapine (on 12/21/2022 at Medicaid.Gov Survey of pharmacy drug pricing)
QUETIAPINE ER 150 MG TABLET Generic $0.27 each
QUETIAPINE ER 200 MG TABLET Generic $0.32 each
QUETIAPINE ER 300 MG TABLET Generic $0.36 each
QUETIAPINE ER 400 MG TABLET Generic $0.41 each
QUETIAPINE ER 50 MG TABLET Generic $0.17 each
QUETIAPINE FUMARATE 100 MG TAB Generic $0.05 each
QUETIAPINE FUMARATE 200 MG TAB Generic $0.11 each
QUETIAPINE FUMARATE 25 MG TAB Generic $0.03 each
QUETIAPINE FUMARATE 300 MG TAB Generic $0.14 each
QUETIAPINE FUMARATE 400 MG TAB Generic $0.18 each
QUETIAPINE FUMARATE 50 MG TAB Generic $0.05 each