Quetiapine

Brand Names: Quetiapine

Drug Class: General Prescription

Overview

11 DESCRIPTION Quetiapine is an atypical antipsychotic belonging to a chemical class, the dibenzothiazepine derivatives. The chemical designation is 2-[2-(4-dibenzo [ b,f ] [1,4]thiazepin-11-yl-1-piperazinyl) ethoxy]-ethanol fumarate (2:1) (salt). It is present in tablets as the fumarate salt. All doses and tablet strengths are expressed as milligrams of base, not as fumarate salt.

Mechanism of Action

12 CLINICAL PHARMACOLOGY 12.1 Mechanism of Action The mechanism of action of quetiapine in the listed indications is unclear. However, the efficacy of quetiapine in these indications could be mediated through a combination of dopamine type 2 (D 2 ) and serotonin type 2 (5HT 2 ) antagonism. The active metabolite, N-desalkyl quetiapine (norquetiapine), has similar activity at D 2 , but greater activity at 5HT2A receptors, than the parent drug (quetiapine). 12.2 Pharmacodynamics Quetiapine and its metabolite, norquetiapine, have affinity for multiple neurotransmitter receptors with norquetiapine binding with higher affinity than quetiapine in general. The Ki values for quetiapine and norquetiapine at the dopamine D1 are 428/99.

Indications

  • 1 INDICATIONS & USAGE Quetiapine is an atypical antipsychotic indicated for the treatment of: Schizophrenia ( 1.1 ) Bipolar I disorder manic episodes ( 1.2 ) Bipolar disorder, depressive episodes ( 1.2 ) 1.1 Schizophrenia Quetiapine is indicated for the treatment of schizophrenia. The efficacy of quetiapine in schizophrenia was established in three 6-week trials in adults and one 6-week trial in adolescents (13 to 17 years).

Common Doses

  • 25 mg
  • 750 mg
  • 800 mg
  • 50 mg

Dosage

2 DOSAGE & ADMINISTRATION · Quetiapine tablets, USP can be taken with or without food ( 2.1 ) Indication Initial Dose Recommended Dose Maximum Dose Schizophrenia-Adults (2.2) 25 mg twice daily 150 to 750 mg/day 750 mg/day Schizophrenia-Adolescents (13 to 17 years) (2.2) 25 mg twice daily 400 to 800 mg/day 800 mg/day Bipolar Mania- Adults Monotherapy or as an adjunct to lithium or divalproex (2.2) 50 mg twice daily 400 to 800 mg/day 800 mg/day Bipolar Mania- Children and Adolescents (10 to 17 years), Monotherapy (2.2) 25 mg twice daily 400 to 600 mg/day 600 mg/day Bipolar Depression-Adults (2.

Black Box Warning

WARNING: INCREASED MORTALITY IN ELDERLY PATIENTS WITH DEMENTIA-RELATED PSYCHOSIS; and SUICIDAL THOUGHTS AND BEHAVIORS Increased Mortality in Elderly Patients with Dementia-Related Psychosis Elderly patients with dementia-related psychosis treated with antipsychotic drugs are at an increased risk of death [ see Warnings and Precautions (5.1) ]. Quetiapine is not approved for the treatment of patients with dementia-related psychosis [ see Warnings and Precautions (5.1) ].

Contraindications

  • 4 CONTRAINDICATIONS Hypersensitivity to quetiapine or to any excipients in the quetiapine formulation. Anaphylactic reactions have been reported in patients treated with quetiapine. Known hypersensitivity to quetiapine or any components in the formulation. ( 4 )

Side Effects

  • 6 ADVERSE REACTIONS The following adverse reactions are discussed in more detail in other sections of the labeling: Increased mortality in elderly patients with dementia-related psychosis [see Warnings and Precautions (5.1) ] Suicidal thoughts and behaviors in adolescents and young adults [see Warnings and Precautions (5.2) ] Cerebrovascular adverse reactions, including stroke in elderly patients with dementia-related psychosis [see Warnings and Precautions (5.3 )] Neuroleptic Malignant Syndrome (NMS) [see Warnings and Precautions (5.

Interactions

  • 7 DRUG INTERACTIONS Concomitant use of strong CYP3A4 inhibitors: Reduce quetiapine dose to one sixth when coadministered with strong CYP3A4 inhibitors (e.g., ketoconazole, ritonavir) ( 2.5 , 7.1 , 12.3 ) Concomitant use of strong CYP3A4 inducers: Increase quetiapine dose up to 5 fold when used in combination with a chronic treatment (more than 7-14 days) of potent CYP3A4 inducers (e.g., phenytoin, rifampin, St. John’s wort) ( 2.6 , 7.1 , 12.3 ) Discontinuation of strong CYP3A4 inducers: Reduce quetiapine dose by 5-fold within 7-14 days of discontinuation of CYP3A4 inducers ( 2.6 , 7.1 , 12.