Quetiapine

Aka: Quetiapine, Seroquel

1. See Also
   1. Quetiapine Overdose
   2. Antipsychotic Medication
   3. Psychosis
2. Class
   1. Atypical Antipsychotic (Second Generation Antipsychotic)
   2. Neuroleptic
   3. Dibenzothiazepine Antipsychotic
3. 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
4. Indications
   1. Schizophrenia
   2. Psychosis in Dementia
   3. Bipolar Disorder
   4. Mania
   5. Major Depression (adjunct)
   6. Autism (not FDA approved)
   7. Insomnia (not FDA approved)
5. 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)
6. 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
7. Adverse Effects: General
   1. Sedation
   2. Headache
   3. Orthostatic Hypotension
   4. Cataract formation
   5. Dry Mouth
   6. Weight gain
   7. Neuroleptic Malignant Syndrome
   8. QTc Prolongation
8. Adverse Effects: Overdose
   1. See Quetiapine Overdose
   2. Somnolence
   3. Tachycardia
   4. Hypotension
9. 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
10. 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
11. Pharmacokinetics
    1. Metabolized by Cytochrome P450 3A4
12. References
    1. Otter and Tomaszewski (2018) Crit Dec Emerg Med 32(8): 32