Quetiapine Pharmacokinetics

Absorption

• Absorbed in the gastrointestinal tract
• Time to reach peak blood levels:
  • Quetiapine IR: 2 hours
  • Quetiapine ER: 6 hours
• Can be taken with food
• Half-life:
  • Approximately 6 hours

Metabolism and drug interactions

Quetiapine is metabolized by cytochrome P450 (CYP) 3A4 to inactive metabolites, drug interactions with inhibitors and inducers are likely to be significant.

• CYP 3A4 inhibitors: these drugs inhibit drug clearance, quetiapine dose may need to be reduced.
  • Ritonavir
  • Erythromycin
  • Ketoconazole
  • Nefazodone
• CYP 3A4 inducers: these drugs accelerate drug clearance, quetiapine dose may need to be increased.
  • Carbamazepine
  • Phenytoin

Renal insufficiency

The manufacturer does not recommend dose adjustment.

Hepatic Insufficiency

According to the manufacturer, dose adjustment may be needed (because of extensive liver metabolism).

More Information on Quetiapine

• Quetiapine Indications: FDA-Approved and Off-label Uses
• Mechanism of Action of Quetiapine
• Quetiapine for Mania
• Quetiapine for Depression
• Quetiapine for Bipolar Depression

References

1. Schatzberg, AF, Nemeroff, C . The American Psychiatric Publishing Textbook of Psychopharmacology. 4th ed.American Psychiatric Publishing, 2009.
2. AstraZeneca Pharmaceuticals LP. Seroquel (quetiapine fumarate) prescribing information. Retrieved from http://www1.astrazeneca-us.com/pi/seroquel.pdf
3. AstraZeneca Pharmaceuticals LP. Seroquel XR( quetiapine fumarate) prescribing information. Retrieved from http://www1.astrazeneca-us.com/pi/seroquelxr.pdf