Quetiapine; Uses, Dosage, Side Effects, Interaction, Pregnancy









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Quetiapine is a dibenzothiazepine derivative with the antipsychotic property. Quetiapine fumarate antagonizes serotonin activity mediated by 5-HT 1A and 5-HT2 receptors. With a lower affinity, this agent also reversibly binds to dopamine D1 and D2 receptors in the mesolimbic and mesocortical areas of the brain leading to decreased psychotic effects, such as hallucinations and delusions. In addition, quetiapine also binds to other alpha-1, alpha-2 adrenergic and histamine H1 receptors.

Quetiapine is indicated for the treatment of schizophrenia as well as for the treatment of acute manic episodes associated with bipolar I disorder.  Quetiapine also has an antagonistic effect on the histamine H1 receptor.It is an atypical antipsychotic used for the treatment of schizophrenia, bipolar disorder, and major depressive disorder. It is also sometimes used as a sleep aid due to its sedating effect, but this use is not recommended. It is taken by mouth.

Mechanism of Action of Quetiapine

Quetiapine’s antipsychotic activity is likely due to a combination of antagonism at D2 receptors in the mesolimbic pathway and 5HT2A receptors in the frontal cortex. Antagonism at D2 receptors relieves positive symptoms while antagonism at 5HT2A receptors relieves negative symptoms of schizophrenia. Quetiapine is a selective monoaminergic antagonist with high affinity for the serotonin Type 2 (5HT2), and dopamine type 2 (D2) receptors. Quetiapine is an antagonist at serotonin 5-HT1A and 5HT2, dopamine D1 and D2, histamine H1, and adrenergic alpha 1 and alpha 2 receptors. Quetiapine has no significant affinity for cholinergic muscarinic or benzodiazepine receptors. Drowsiness and orthostatic hypotension associated with the use of quetiapine may be explained by its antagonism of histamine H1 and adrenergic alpha 1 receptors, respectively. Quetiapine’s antagonism of adrenergic a1 receptors may explain the orthostatic hypotension observed with this drug.

Indications of Quetiapine

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Contra Indications of Quetiapine

Dosage of Quetiapine

Strengths: 25 mg; 100 mg; 200 mg; 300 mg; 50 mg; 400 mg; 150 mg

Schizophrenia

Immediate-release tablets

  • Day 1: 25 mg orally twice a day
  • Days 2 and 3: Increase in 25 to 50 mg increments divided 2 or 3 times daily with the goal of achieving a total daily dose of 300 to 400 mg by day 4
  • Further dose adjustments should be made in 25 to 50 mg increments twice a day in intervals of not less than 2 days
  • Recommended dose: 150 to 750 mg orally per day in divided doses
  • Maximum dose: 750 mg/day

Extended-release (XR) tablets

  • Day 1: 300 mg orally once a day
  • Increase in increments of up to 300 mg/day
  • Recommended dose: 400 to 800 mg orally once a day
  • Maximum dose: 800 mg/day

Pediatric  Bipolar Disorder

Age: 10 to 17 years:
Special Considerations in Treating Pediatric Bipolar 1 Disorder

  • Prior to initiating medication therapy, a thorough diagnostic evaluation carefully considering the risks associated with medication treatment should be performed.
  • Medication treatment should be a part of a total treatment program that often includes psychological, educational, and social interventions.

 Depression

Extended-release (XR) tablets

  • Initial dose: 50 mg orally once a day
  • Dose increases should be made in increments of 50 mg/day depending on clinical response and tolerabilit
  • Recommended dose: 150 mg to 300 mg orally once a day
  • Maximum dose: 300 mg/day
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Bipolar Disorder

MANIA Associated with Bipolar Disorder (as monotherapy or as an adjunct therapy to lithium or divalproex)
Immediate-release (IR) tablets

  • Initial dose: 25 mg orally twice a day
  • Dose increases should be made in increments of 50 mg/day depending on clinical response and tolerability
  • Recommended dose: 400 to 800 mg orally per day in divided doses
  • Maximum dose: 800 mg/day

Extended-release (XR) tablets

  • Initial dose: 50 mg orally once a day
  • Dose increases should be made in increments of 50 mg/day depending on clinical response and tolerability
  • Recommended dose: 400 to 800 mg/day
  • Maximum dose: 800 mg/day

DEPRESSIVE Episodes Associated with Bipolar Disorder
Immediate-release (IR) tablets

  • flatulence,
  • Initial dose: 25 mg orally twice a day
  • Dose increases should be made in increments of 50 mg/day depending on clinical response and tolerability
  • Recommended dose: 300 mg/day
  • Maximum dose: 300 mg/day

Extended-release (XR) tablets

  • Initial dose: 50 mg orally once a day
  • Dose increases should be made in increments of 50 mg/day depending on clinical response and tolerability
  • Recommended dose: 300 mg/day
  • Maximum dose: 300 mg/day

Side Effects of Quetiapine

The most common

More common

Less common

Drug Interactions of Quetiapine

Quetiapine acetate may interact with following drugs, supplements & may decrease the efficacy of the drug
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Pregnancy & Lactation of Quetiapine

FDA Pregnancy Catagory C

Pregnancy

The safety of quetiapine use during pregnancy is not known. This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Lactation

This medication passes into breast milk. If you are a breastfeeding mother and are taking quetiapine it may affect yo ur baby.Talk to your doctor about whether you should continue breastfeeding. The safety and efficacy of this medication have not been established for children under 18 years of age.

References

 

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