Seroquel

What is Seroquel (Quetiapine)?

Seroquel, marketed under the generic name Quetiapine, is an atypical antipsychotic medication used for treating schizophrenia, bipolar disorder, and major depressive disorder (as an adjunct treatment). It has sedative properties and is often used off-label for anxiety and sleep disorders.

Seroquel Brand Names

USA & Canada:

• Seroquel
• Seroquel XR

Europe & Other Regions:

• Seroquel
• Quetiapine (generic versions available)

Mechanism of Action

Quetiapine is an atypical antipsychotic that works by altering the activity of certain neurotransmitters in the brain. It has affinity for multiple receptor types, including:

• Serotonin 5-HT2A receptors (antagonist)
• Dopamine D2 receptors (antagonist)
• Histamine H1 receptors (antagonist)
• Alpha-1 adrenergic receptors (antagonist)
• Alpha-2 adrenergic receptors (antagonist)

Pharmacokinetics

• Bioavailability: 100%
• Peak Plasma Levels: ~1.5 hours (immediate release), ~6 hours (extended release)
• Half-life: ~7 hours
• Metabolism: Primarily by CYP3A4 enzyme
• Steady State: Achieved within 2 days

Seroquel Dosage Forms

Extended-release formulations provide smoother drug levels and are taken once daily, often in the evening.

Storage Requirements

• Store at room temperature (20-25°C)
• Protect from moisture and light
• Keep in original container

How Does Seroquel Work?

Seroquel works by blocking dopamine and serotonin receptors, reducing symptoms of schizophrenia, bipolar disorder, and depression.

1. Neurotransmitter Receptor Antagonism

• Dopamine Receptors: Quetiapine acts as an antagonist at dopamine D2 receptors in the mesolimbic pathway, which reduces the hyperactivity of dopamine pathways thought to be involved in psychotic symptoms like hallucinations and delusions. However, its action on D2 receptors is relatively weak compared to first-generation antipsychotics, which contributes to fewer extrapyramidal side effects (EPS).
• Serotonin Receptors: It also has significant antagonist activity at serotonin 5-HT2A receptors. This dual action on dopamine and serotonin pathways is a hallmark of atypical antipsychotics, which generally leads to better efficacy for both positive (hallucinations, delusions) and negative symptoms (social withdrawal, apathy) of schizophrenia, as well as mood stabilization.

2. Other Receptor Interactions

• Histamine H1 Receptors: Quetiapine has a high affinity for histamine H1 receptors, which explains its sedative effects, particularly at lower doses, making it useful for sleep disturbances or as an anxiolytic.
• Adrenergic Receptors: It shows antagonism at alpha-1 adrenergic receptors, which can lead to orthostatic hypotension but also contributes to its anxiolytic effects.
• Muscarinic Receptors: There’s a moderate affinity for muscarinic M1 receptors, which can cause anticholinergic side effects like dry mouth, constipation, or blurred vision.

What is Seroquel mostly used for?

Seroquel is FDA-approved for:

• Schizophrenia (Adults and Adolescents)
• Bipolar Disorder (Mania, Depression, and Maintenance)
• Major Depressive Disorder (Adjunct therapy)

Off-Label Uses:

• Generalized Anxiety Disorder (GAD)
• Insomnia
• PTSD

Seroquel Dosage and Administration

Here’s a detailed breakdown of recommended dosages for Seroquel (Quetiapine) based on diagnosis and age, gathered from various sources:

Seroquel For Schizophrenia

Adults:

• Initial Dose: Start at 25 mg twice daily, with increments of 25-50 mg/day to an effective dose by day 4-7, typically between 300-400 mg/day in two or three divided doses.
• Maintenance Dose: 400 to 800 mg/day. The dose can be adjusted based on response and tolerability, with some studies suggesting benefits up to 750 mg/day.

Adolescents (Ages 13-17):

• Initial Dose: 25 mg twice daily, with titration over 5 days to 400 mg/day in divided doses.
• Maintenance Dose: The usual range is 400 to 800 mg/day, with the maximum recommended dose being 800 mg/day.

Seroquel for Bipolar Disorder

Manic Episodes (Bipolar I) – Adults:

• Initial Dose: Begin with 50 mg twice daily, increasing by 50 mg/day to reach 400-800 mg/day based on response.
• Maintenance Dose: For maintenance treatment after manic episode stabilization, a range of 400-800 mg/day is often used.

Manic Episodes (Bipolar I) – Children (Ages 10-17):

• Initial Dose: 25 mg twice daily, titrated to 400-600 mg/day over several days.
• Maintenance Dose: Similar to the initial dose range, with adjustments based on individual response.

Depressive Episodes (Bipolar I and II) – Adults:

Initial Dose: Start with 50 mg/day, increasing to 300 mg/day based on response, usually in divided doses or as an extended-release formulation.

Seroquel Major Depressive Disorder (Adjunctive Therapy)

Adults:

• Initial Dose: 50 mg/day, titrated to 150-300 mg/day. The extended-release formulation is often used here for once-daily dosing.

Considerations for Dosage Adjustments:

• Elderly Patients (65 years and older): Start with lower doses (e.g., 50 mg/day) and titrate more slowly due to potential for increased sensitivity to side effects and pharmacokinetic changes.
• Hepatic Impairment: Begin with 25 mg/day, with cautious increments, as quetiapine is extensively metabolized by the liver.
• Renal Impairment: Although there’s limited data, starting at lower doses and titrating cautiously is advised due to potential for altered metabolism or clearance.

General Notes:

• Dosages should always be tailored to the individual’s response, with the lowest effective dose being the goal to minimize side effects.
• The immediate-release form is typically dosed twice daily, while the extended-release (Seroquel XR) can be given once daily at bedtime for some conditions to reduce daytime sedation.

Administration Tips:

• Can be taken with or without food
• Extended-release tablets should be taken once daily in the evening
• Tablets must not be crushed or chewed

Treatment Duration

• Chronic conditions require long-term use
• Gradual discontinuation is necessary to prevent withdrawal effects

Side Effects of Seroquel

Common (>10%):

• Sedation/Drowsiness
• Dizziness
• Dry mouth
• Weight gain
• Constipation

Less Common (1-10%):

• Increased appetite
• Hypotension
• Fatigue
• Blurred vision

Serious but Rare:

• Tardive Dyskinesia (involuntary movements)
• Neuroleptic Malignant Syndrome (muscle rigidity, fever)
• QT Prolongation (heart rhythm issues)
• Metabolic changes (diabetes, cholesterol increase)

Contraindications & Precautions

• Contraindicated in patients with hypersensitivity to Quetiapine
• Use with caution in:
  • Diabetes (may increase blood sugar)
  • Heart disease (risk of QT prolongation)
  • Elderly patients with dementia (increased mortality risk)

Seroquel and other drugs Interactions

CYP3A4 Inhibitors (Increase Quetiapine Levels):

• Ketoconazole
• Erythromycin
• Ritonavir

→ Reduce Seroquel dose by 50%

CYP3A4 Inducers (Decrease Quetiapine Levels):

• Carbamazepine
• Rifampin
• Phenytoin

→ May require dose increase

Patient Monitoring

Baseline Tests:

• Complete Blood Count (CBC)
• Lipid Profile
• Blood Sugar Levels
• ECG (if cardiac risk factors)
• Weight & BMI

Ongoing Monitoring:

• Weight & Metabolic Checks (Every 3-6 months)
• Blood Sugar Monitoring (Especially in diabetics)
• Annual Lipid & Cholesterol Screening
• Blood Pressure Checks

Special Populations

Elderly:

• Lower starting doses (25-50 mg/day)
• Higher risk of dizziness & falls

Pregnancy & Breastfeeding:

• Category C (Risk/benefit must be assessed)
• May cause withdrawal symptoms in newborns

Renal & Hepatic Impairment:

• Use caution in severe liver disease
• No dose adjustment needed for mild impairment

Seroquel vs. Other Antipsychotics

Seroquel vs. Risperidone

Seroquel vs. Olanzapine

Seroquel vs. Aripiprazole

Clinical Considerations for Choosing Seroquel

When Seroquel is Preferred:

• Patients with sleep disturbances
• Bipolar depression
• Patients prone to anxiety
• Lower risk of movement disorders

When Other Antipsychotics Are Preferred:

• Risperidone: For acute psychosis and aggression
• Aripiprazole: For young patients & cognitive clarity
• Olanzapine: For severe, treatment-resistant cases

Cost & Availability

• Available as a generic (Quetiapine), making it affordable
• Extended-release (XR) version is more expensive
• Insurance coverage varies

Questions and Answers about Seroquel

Is Seroquel like Xanax?

No, Seroquel (quetiapine) and Xanax (alprazolam) are different medications. Seroquel is an atypical antipsychotic, while Xanax is a benzodiazepine. They have different mechanisms of action and are used to treat different conditions.

Is Seroquel a strong sleeping pill?

Seroquel is not primarily a sleeping pill. While it can cause drowsiness as a side effect, it is not FDA-approved for treating insomnia. Some doctors prescribe it off-label for sleep at low doses, but this practice is controversial due to potential risks and side effects.

Does Seroquel calm anxiety?

Seroquel may help with anxiety in some cases, particularly when used off-label. It affects neurotransmitters in the brain that play a role in mood and anxiety. It is not typically a first-line treatment for anxiety disorders.

Does Seroquel dull your emotions?

Seroquel can affect mood and cognition. Some people may experience changes in their emotional state, including feeling less reactive or experiencing mood swings. Individual responses can vary.

Does quetiapine cause hypersexuality?

There is no direct evidence in the provided search results indicating that quetiapine causes hypersexuality. In fact, Seroquel may cause decreased libido in some patients.

Is 25mg of quetiapine a lot?

25mg of quetiapine is generally considered a low dose. When used off-label for sleep, doses typically range from 25mg to 100mg. However, the appropriate dose depends on the individual and the condition being treated.

Who should not take Seroquel?

Seroquel may not be suitable for everyone. It should be used with caution in elderly patients with dementia-related psychosis due to increased mortality risk. People with certain medical conditions, those taking specific medications, and individuals with a history of substance abuse may need to avoid Seroquel or use it under close medical supervision.

Sources:

• https://www.drugs.com/seroquel.html
• https://www.rxlist.com/seroquel-drug.htm
• https://greenhousetreatment.com/what-is-seroquel/long-term-effects/
• https://www.medicalnewstoday.com/articles/drugs-seroquel
• https://www.drugs.com/quetiapine.html
• https://go.drugbank.com/drugs/DB01224
• https://my.clevelandclinic.org/health/drugs/19288-quetiapine-tablets
• https://pmc.ncbi.nlm.nih.gov/articles/PMC7869656/
• https://en.wikipedia.org/wiki/Seroquil
• https://www.nhs.uk/medicines/quetiapine/about-quetiapine/