Pharm

Quetiapine

search

Quetiapine, Seroquel

  • Class
  • Mechanism
  1. Dopamine, Serotonin, histamine and adrenergic antagonist
  2. Potent alpha-1 Adrenergic Receptor antagonist (risk of Hypotension)
  3. Weak antagonist at Dopamine (D2), muscarinic (M1) and Serotonin (5HT-1A) with risk of sedation
  • Indications
  • 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)
  • 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
  • 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
  • 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
  • Pharmacokinetics
  1. Metabolized by Cytochrome P450 3A4
  • References
  1. Otter and Tomaszewski (2018) Crit Dec Emerg Med 32(8): 32