Quetiapine (Dosage)

Quetiapine is an atypical antipsychotic drug used for the treatment of schizophrenia, bipolar disorder and major depressive disorder. Several clinical trials have demonstrated the relationship between the pharmacokinetics of quetiapine and genetic polymorphisms of the cytochrome CYP3A4, directly involved in its metabolism.

Quetiapine is an atypical antipsychotic used in the treatment of schizophrenia and manic and depressive episodes of bipolar disorder.


Quetiapine interacts with a wide range of neurotransmitter receptors. It has affinity for cerebral serotonin (5-HT2) and D1 / D2 dopamine receptors, as well as alpha 1 adrenergic and histaminergic, alpha 2 adrenergic and 5HT1A serotonin receptors.

Quetiapine has a similar efficacy to other neuroleptics on positive psychotic symptoms; it is also effective on persistent positive symptoms (although there are no comparative data with clozapine).

Extrapyramidal side effects are less intense than those of classic antipsychotics, but there is a higher incidence of metabolic effects.


Somnolence, dizziness, asthenia, orthostatic hypotension and syncope (especially when initiating therapy). Gastrointestinal symptoms, constipation, dry mouth, elevated liver enzymes, hyperglycemia, weight gain, seizures, neuroleptic malignant syndrome, slight decrease in total T4 and free T4, extrapyramidal symptoms, early or late dyskinesia, akathisia.


Hypersensitivity to quetiapine. Avoid concomitancy with cytochrome P450 3A4 inhibitors (such as HIV protease inhibitors, azole antifungals, erythromycin, clarithromycin and nefazodone).


Caution when prescribed with other centrally acting drugs and alcohol.

Inhibitors of cytochrome P450 3A4 (ketoconazole, itraconazole, erythromycin, clarithromycin, grapefruit juice, antiretroviral protease inhibitors, nefazone, etc.) may increase quetiapine levels: avoid their use together.

Phenytoin, carbamazepine, rifampicin, and thioridazine may decrease quetiapine levels.

Quetiapine increases its clearance with: carbamazepine, phenytoin and thioridazine.


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  • Psicotric ®
  • Qudix ®
  • Quentiax ®
  • Quentiamylan ®
  • Rocoz ®
  • Seroquel ®

Genes analyzed



Bakken GV, Molden E, Hermann M. Impact of genetic variability in CYP2D6, CYP3A5, and ABCB1 on serum concentrations of quetiapine and N-desalkylquetiapine in psychiatric patients. Ther Drug Monit. 2015 Apr;37(2):256-61.

Beunk L, Nijenhuis M, Soree B, et al. Dutch Pharmacogenetics Working Group (DPWG) guideline for the gene-drug interaction between CYP2D6, CYP3A4 and CYP1A2 and antipsychotics. Eur J Hum Genet. 2024 Mar;32(3):278-285.

Solhaug V, Tveito M, Waade RB, et al. Impact of age, sex and cytochrome P450 genotype on quetiapine and N-desalkylquetiapine serum concentrations: A study based on real-world data from 8118 patients. Br J Clin Pharmacol. 2023 Dec;89(12):3503-3511.

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