Quetiapine

Neuroleptic, Second-generation (atypical) neuroleptic, Dibenzothiazepine, Serotonin-dopamine antagonist

Quetiapine

Seroquel

Quetiapine, marketed as Seroquel, is the most widely prescribed neuroleptic medicine in the United States, accounting for approximately 28% of neuroleptic prescriptions. It is a dibenzothiazepine atypical neuroleptic developed in 1985 at the pharmaceutical division of Imperial Chemical Industries in Macclesfield, United Kingdom (later Zeneca, then AstraZeneca), and approved by the United States Food and Drug Administration on 26 September 1997 for the treatment of schizophrenia. Subsequent FDA approvals expanded the labeled indications to include acute bipolar mania (2004), bipolar depression (2006), bipolar maintenance (2008), and adjunctive treatment of major depressive disorder (2009). Quetiapine is widely prescribed at low doses (25-150 mg) off-label for insomnia, anxiety, agitation, post-traumatic stress disorder, and behavioral disturbances of dementia; this off-label use accounts for the dominant share of quetiapine prescribing in the United States and most other markets. The off-label prescribing pattern was the subject of the largest civil settlement for off-label marketing in pharmaceutical history at the time, when AstraZeneca paid $520 million to the United States Department of Justice in 2010 to resolve allegations that the company had illegally marketed Seroquel for indications never approved by the FDA.

History

Quetiapine emerged from a structure-activity exploration of clozapine analogues at the pharmaceutical division of Imperial Chemical Industries, then headquartered at Mereside in Macclesfield in the United Kingdom. The work began in the late 1970s in the wake of the clinical re-emergence of clozapine, which had been withdrawn in 1975 after a cluster of agranulocytosis deaths in Finland but was already recognized as the first neuroleptic with substantially lower extrapyramidal toxicity than the first-generation neuroleptics. ICI chemists pursued analogues of perlapin and fluperlapin, two dibenzazepine and dibenzothiazepine compounds with structural resemblance to clozapine but without its hematologic liability. The lead compound, then called ICI-204636, was synthesized in 1985 and is now known as quetiapine.

Imperial Chemical Industries spun off its pharmaceuticals division as Zeneca in 1993, which merged with the Swedish pharmaceutical company Astra to form AstraZeneca in 1999. The pivotal clinical trial for the United States registration package was Arvanitis and Miller's "Seroquel Trial 13," a multiple-fixed-dose comparison against haloperidol and placebo in patients with acute exacerbation of schizophrenia, published in Biological Psychiatry in 1997 and the basis for the FDA submission.

The early preclinical safety story was dominated by an unusual finding: in toxicology studies in beagles, quetiapine produced posterior subcapsular cataracts at high doses, raising the question of whether the medicine might be cataractogenic in humans. The signal shaped both the development program and the early monitoring guidance, which initially included slit-lamp examinations every six months. By the early 2010s, a series of human studies including direct comparisons against risperidone failed to confirm an excess of cataract formation in patients on quetiapine, and the surveillance recommendation has since been retired.

The FDA approved quetiapine for the treatment of schizophrenia on 26 September 1997, making it the fourth atypical neuroleptic to reach the United States market after clozapine (1989), risperidone (1993), and olanzapine (1996). AstraZeneca launched Seroquel in late 1997.

The CATIE study (the Clinical Antipsychotic Trials of Intervention Effectiveness, an independent NIMH-funded randomized comparison of olanzapine, perphenazine, quetiapine, risperidone, and ziprasidone in 1,493 patients with chronic schizophrenia) was published in the New England Journal of Medicine in 2005 and remains the largest independent comparative effectiveness trial of neuroleptics ever conducted. The primary outcome was time to discontinuation for any cause; 74% of patients discontinued their assigned treatment before 18 months. Olanzapine had a significantly longer time to discontinuation than quetiapine or risperidone, though it was also associated with greater weight gain, hyperlipidemia, and hyperglycemia (the metabolic concern that came to define olanzapine's clinical positioning). The CATIE finding that quetiapine was less durable than olanzapine in chronic schizophrenia, taken together with its metabolic profile, complicated the company's positioning of Seroquel as the preferred atypical for first-episode patients.

Beginning in 2004, AstraZeneca pursued a series of indication expansions that shaped the medicine's commercial trajectory. The FDA approved quetiapine for acute bipolar mania in January 2004 (later extending to monotherapy and adjunctive use with Lithium or divalproex), for acute bipolar depression in October 2006, for the maintenance treatment of bipolar I disorder in May 2008, and for adjunctive treatment of major depressive disorder in adults in December 2009. Seroquel XR, the once-daily extended-release formulation, was approved on 17 May 2007. Pediatric indications followed in December 2009: schizophrenia in adolescents aged 13-17 and acute bipolar mania in children and adolescents aged 10-17.

The 2010 Department of Justice settlement reshaped the public understanding of how quetiapine was actually being used. On 27 April 2010, AstraZeneca agreed to pay the United States government $520 million to resolve civil allegations that the company had illegally marketed Seroquel for non-approved indications between January 2001 and December 2006. The settlement, which the Department of Justice described as the largest civil-only off-label marketing settlement in pharmaceutical history at the time, alleged that AstraZeneca had promoted Seroquel for "aggression, Alzheimer's disease, anger management, anxiety, attention deficit hyperactivity disorder, bipolar maintenance, dementia, depression, mood disorder, post-traumatic stress disorder, and sleeplessness"; that the company had targeted primary care physicians, geriatricians, pediatricians, long-term care facilities, and prisons rather than the psychiatrists who treat the medicine's approved indications; that it had paid physicians to attend advisory meetings at resort locations and to sign onto company-authored articles promoting the off-label uses; and that these activities constituted both a False Claims Act violation (through reimbursement of off-label use by federal health programs) and Anti-Kickback Statute violations. AstraZeneca denied the allegations but signed a Corporate Integrity Agreement with the Office of the Inspector General of the Department of Health and Human Services. By the time of the settlement, AstraZeneca was facing more than 25,000 product liability lawsuits alleging that Seroquel had caused diabetes in plaintiffs prescribed the medicine off-label.

Quetiapine's United States composition-of-matter patent expired in March 2012; generic quetiapine reached the market the same year and rapidly captured the majority of prescribing. The pediatric indication expansion in 2009 had been pursued in part to extend exclusivity, but the additional six months of pediatric exclusivity ended in September 2012. Generic competition reduced AstraZeneca's Seroquel revenues sharply but did not slow the overall prescribing trajectory; quetiapine prescribing has continued to increase since the patent expiration, driven primarily by low-dose off-label use.

The contemporary academic and regulatory literature has focused on documenting the off-label prescribing pattern and on the question of whether low-dose use carries the same metabolic risks as full neuroleptic doses. Pringsheim and Gardner's 2014 review of Canadian prescribing data found that low-dose quetiapine had become one of the most common prescriptions in Canadian primary care, predominantly for insomnia and anxiety. Multiple subsequent observational studies have reported that even low-dose use is associated with weight gain, metabolic dysregulation, and an increased risk of major adverse cardiovascular events. The Cleveland Clinic Journal of Medicine in 2021 published a clinical review explicitly recommending against the use of quetiapine for primary insomnia, the indication for which it is most commonly prescribed off-label. Australian and European clinical guidelines have similarly cautioned against the practice. The prescribing pattern has continued nonetheless; the editorial story of quetiapine in the United States is that its dominant indication is one that no clinical guideline supports.

Experience

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Problems

Schizophrenia★★★★★★★★★★★★★★★—××

FDA-approved for the treatment of schizophrenia in adults (1997) and in adolescents aged 13-17 (2009).

Bipolar I Disorder★★★★★★★★★★★★★★★—××

FDA-approved for the acute treatment of manic episodes associated with bipolar I disorder in adults (2004), both as monotherapy and as adjunctive therapy with lithium or divalproex. Also approved for children and adolescents aged 10-17 (2009).

Bipolar Disorder★★★★★★★★★★★★★★★—××

FDA-approved for the acute treatment of depressive episodes associated with bipolar disorder in adults (2006). One of the few medicines with a formal indication for the depressive pole of bipolar illness, distinguishing it from most other atypical neuroleptics.

Bipolar I Disorder★★★★★★★★★★★★★★★—××

FDA-approved for the maintenance treatment of bipolar I disorder in adults, as adjunctive therapy to lithium or divalproex (2008).

Major Depressive Disorder★★★★★★★★★★★★★★★—××

FDA-approved as adjunctive therapy to antidepressants for the treatment of major depressive disorder in adults (2009). Approved only for the extended-release formulation (Seroquel XR).

Insomnia★★★★★★★★★★★★★★★—××

Off-label. The single most common reason quetiapine is prescribed in primary care and in psychiatric outpatient practice. The evidence base for low-dose quetiapine in primary insomnia is limited and mixed; no major clinical guideline supports the indication. The Cleveland Clinic Journal of Medicine, Australian therapeutic guidelines, the American Academy of Sleep Medicine, and the European Sleep Research Society all advise against routine use of quetiapine for primary insomnia, citing the metabolic and cardiovascular risk profile.

Anxiety★★★★★★★★★★★★★★★—××

Off-label. Quetiapine is widely prescribed off-label for generalized anxiety, panic, and post-traumatic stress disorder, often at doses below 200 mg. The evidence base is limited. SSRIs and SNRIs remain first-line for these indications; quetiapine should not be a primary anxiety treatment.

Agitation in the setting of dementia★★★★★★★★★★★★★★★—××

Off-label, with caution. Quetiapine is sometimes prescribed for the behavioral and psychological symptoms of dementia, including agitation and psychosis. All atypical neuroleptics carry a boxed warning for increased mortality in elderly patients with dementia-related psychosis; use should be reserved for cases where non-pharmacologic interventions have failed and where the clinical risk-benefit balance has been individually documented.

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Titration strategies

Schizophrenia (adult)▲0▼×

Immediate-release: Start at 25 mg twice daily on day 1. Increase by 25-50 mg twice or three times daily on days 2 and 3, to a target dose of 300-400 mg/day given in divided doses by day 4. Further adjustment by 25-50 mg twice daily at intervals of at least two days; typical effective range is 150-750 mg/day. Maximum recommended dose 800 mg/day. Extended-release (Seroquel XR): Start at 300 mg once daily in the evening. Increase by up to 300 mg/day in increments of 1-2 days; typical effective range is 400-800 mg once daily.

Bipolar mania (adult)▲0▼×

Immediate-release: Start at 50 mg twice daily on day 1. Titrate to 200 mg twice daily by day 4 (100 mg increments daily). Further adjustment to 800 mg/day maximum, typical effective range 400-800 mg/day in divided doses. Extended-release (Seroquel XR): Start at 300 mg once daily in the evening on day 1. Increase to 600 mg on day 2; typical effective range 400-800 mg once daily.

Bipolar depression (adult)▲0▼×

Start at 50 mg once daily at bedtime. Titrate to 300 mg by day 4 (50 mg increments: 100 mg on day 2, 200 mg on day 3, 300 mg on day 4). Target dose 300 mg once daily at bedtime; doses above 300 mg have not been shown to provide additional benefit and increase adverse effect burden.

MDD adjunct (adult, Seroquel XR only)▲0▼×

Start at 50 mg once daily at bedtime on days 1 and 2. Increase to 150 mg once daily on day 3; further increase to 300 mg if needed at 1-week intervals. Typical effective dose 150-300 mg once daily.

Elderly▲0▼×

Start at 25 mg once daily. Titrate slowly by 25-50 mg/day every 1-2 days based on response and tolerability. Elderly patients have reduced clearance, increased sensitivity to orthostatic hypotension, and substantially elevated risk of falls. The boxed warning for atypical neuroleptic use in elderly patients with dementia-related psychosis applies.

Hepatic impairment▲0▼×

Start at 25 mg once daily. Titrate by 25-50 mg/day to clinical effect. Quetiapine clearance is reduced approximately 30% in hepatic impairment.

Discontinuation taper▲0▼×

For patients on stable doses of quetiapine for psychotic illness or bipolar disorder, discontinuation should not be considered without careful assessment of relapse risk. When discontinuation is clinically appropriate, the contemporary deprescribing standard (Maudsley Deprescribing Guidelines, Horowitz and Taylor 2024) favors hyperbolic tapering rather than linear dose reduction: approximately 10% reductions of the current dose every 2-4 weeks, with intervals lengthening as the dose falls. The principle reflects the hyperbolic relationship between dose and dopamine D2 receptor occupancy, which means that equal absolute dose decrements produce progressively larger reductions in receptor occupancy at lower doses. For patients on low-dose quetiapine for off-label indications such as insomnia or anxiety, deprescribing is generally appropriate, but the same hyperbolic principles apply: abrupt discontinuation of quetiapine can produce withdrawal insomnia, anxiety rebound, nausea, and (uncommonly) cholinergic rebound and dyskinesia. Reduce by approximately 25-50% every 1-2 weeks for low-dose users, slower if rebound symptoms emerge.

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Effects

• Somnolence / sedation👤 no reports yet⚕️ no reports yetRate×

  The dominant short-term effect at any dose; the basis for the off-label sleep use. Histamine H1 receptor antagonism at low doses (25-100 mg) produces sedation without neuroleptic effect.
• Weight gain👤 no reports yet⚕️ no reports yetRate×

  Substantial and clinically meaningful; reported across the dose range including at low off-label doses. Mean weight gain in registration trials approximately 2-3 kg over 6 weeks; long-term weight gain frequently exceeds 7% of baseline body weight, the threshold for clinically significant weight gain.
• Metabolic syndrome👤 no reports yet⚕️ no reports yetRate×

  Quetiapine is associated with substantial increases in fasting glucose, triglycerides, and LDL cholesterol and with development of frank type 2 diabetes mellitus. The metabolic risk is intermediate among atypical neuroleptics: greater than ziprasidone, aripiprazole, or lurasidone; less than olanzapine or clozapine. The metabolic effect is present at low off-label doses though smaller in magnitude than at full neuroleptic doses.
• Orthostatic hypotension👤 no reports yet⚕️ no reports yetRate×

  Common, particularly early in treatment and after dose increases; the basis for the gradual titration schedule. Alpha-1 adrenergic receptor antagonism is the mechanism. Substantially increased fall risk in elderly patients.
• Anticholinergic effects👤 no reports yet⚕️ no reports yetRate×

  Dry mouth, constipation, urinary retention, blurred vision; modest muscarinic affinity drives these. Tolerance to most anticholinergic effects develops over weeks of treatment.
• QT prolongation👤 no reports yet⚕️ no reports yetRate×

  Modest dose-dependent QT prolongation; clinically significant primarily in overdose or in combination with other QT-prolonging medicines.
• Hyperprolactinemia👤 no reports yet⚕️ no reports yetRate×

  Substantially less than risperidone, haloperidol, or first-generation neuroleptics; transient elevations may occur but sustained hyperprolactinemia is uncommon.
• Extrapyramidal effects👤 no reports yet⚕️ no reports yetRate×

  Lower than first-generation neuroleptics or risperidone but not absent; acute akathisia, parkinsonism, and (with long-term use) tardive dyskinesia are recognized risks.
• Neuroleptic malignant syndrome👤 no reports yet⚕️ no reports yetRate×

  Rare but documented with all neuroleptics including quetiapine.
• Seizure/Epileptic fit👤 no reports yet⚕️ no reports yetRate×

  Rare; quetiapine lowers seizure threshold modestly. Caution in patients with seizure disorder.
• Agranulocytosis👤 no reports yet⚕️ no reports yetRate×

  Uncommon; less than clozapine but reported. Routine CBC monitoring is not required but white blood cell count should be checked if infection or signs of neutropenia develop.
• Falls👤 no reports yet⚕️ no reports yetRate×

  Substantially elevated in elderly patients on quetiapine, primarily from orthostasis and sedation. A leading cause of quetiapine-related morbidity in older adults.

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Pharmacokinetics

Absorption

Quetiapine is rapidly absorbed after oral administration; peak plasma concentrations of the immediate-release tablet occur approximately 1.5 hours after dosing. The tablet formulation is essentially completely bioavailable (~100%) relative to oral solution, but the parent compound is extensively metabolized on first pass through the liver, and the doses required for clinical effect are correspondingly larger than what reaches the systemic circulation in unchanged form. The extended-release formulation produces a slower, more sustained absorption profile with peak levels at approximately 6 hours and substantially flatter plasma trajectories. High-fat meals increase the Cmax of the extended-release formulation by approximately 50% and the AUC by approximately 20%, leading to the labeled recommendation that Seroquel XR be taken without food or after a light meal.

Distribution

Plasma protein binding is approximately 83%, primarily to albumin and alpha-1-acid glycoprotein. Volume of distribution approximately 10 L/kg. Quetiapine crosses the blood-brain barrier readily and the placenta in modest amounts; it is excreted into breast milk at low concentrations.

Metabolism

Quetiapine is extensively metabolized in the liver, predominantly via CYP3A4, with minor contributions from CYP2D6. The principal active metabolite is N-desalkylquetiapine (also called norquetiapine), formed via CYP3A4-mediated dealkylation; norquetiapine has a longer half-life (~9-12 hours) than the parent compound (~6 hours) and a distinct receptor binding profile, with substantially higher affinity for the norepinephrine transporter (NET) than the parent compound. The norquetiapine NET binding is one mechanism proposed for quetiapine's efficacy in bipolar depression and as an MDD adjunct, distinguishing it pharmacodynamically from neuroleptics whose active metabolites are less behaviorally distinctive. Several other inactive metabolites are formed in lesser amounts. Quetiapine itself has negligible CYP-inhibitory activity but is sensitive to inhibition and induction of CYP3A4.

Elimination

Elimination is renal (73%) and fecal (20%), almost entirely as metabolites; less than 1% of an oral dose is recovered unchanged in urine. Mean parent half-life is approximately 6 hours for immediate-release quetiapine; the active norquetiapine metabolite has a half-life of approximately 9-12 hours and contributes meaningfully to the clinical duration of action. Half-life is prolonged in elderly patients (mean clearance reduced approximately 30-50%) and in hepatic impairment.

Pharmacodynamics

Quetiapine is a broad-receptor-binding atypical neuroleptic with the receptor profile that defines the second-generation class: substantial antagonism at both serotonin 5-HT2A and dopamine D2 receptors, with the 5-HT2A:D2 affinity ratio higher than at the older neuroleptics. The conventional explanation for the lower extrapyramidal liability of atypical neuroleptics is that pre-frontal 5-HT2A antagonism increases mesocortical dopamine release while striatal D2 occupancy is partial, reducing the basal-ganglia dopamine blockade that drives the movement-disorder spectrum.

Quetiapine's receptor binding extends well beyond the prototypical 5-HT2A/D2 profile. The medicine has high affinity at histamine H1 receptors (mediating sedation and contributing to weight gain), at alpha-1 adrenergic receptors (mediating orthostatic hypotension), and modest affinity at muscarinic M1 receptors (mediating anticholinergic effects). It has notably low affinity for dopamine D2 receptors compared with other atypicals, with rapid dissociation kinetics; the "loose binding" model proposes that this rapid dissociation underlies quetiapine's particularly low extrapyramidal side-effect burden but also its modest neuroleptic potency at low doses.

The active metabolite norquetiapine (N-desalkylquetiapine) has a substantially different receptor profile from the parent compound, with high affinity for the norepinephrine transporter (NET), partial agonism at 5-HT1A, and antagonism at 5-HT2C. The norquetiapine receptor profile resembles that of an atypical antidepressant more than that of a neuroleptic; the contribution of norquetiapine to quetiapine's antidepressant efficacy in bipolar depression and MDD adjunct is the leading pharmacodynamic explanation for the medicine's mood activity.

The pharmacodynamics are markedly dose-dependent. At low doses (25-100 mg), histamine H1 antagonism predominates clinically, producing sedation without meaningful neuroleptic effect, the basis for the medicine's off-label use in sleep. At intermediate doses (150-300 mg), serotonin antagonism (parent and norquetiapine) and norepinephrine reuptake inhibition (norquetiapine) become clinically relevant; this dose range supports the antidepressant indication. At full neuroleptic doses (400-800 mg), D2 receptor occupancy rises to the 60-80% range typically associated with neuroleptic efficacy. The progressive recruitment of pharmacologic targets across the dose range distinguishes quetiapine from neuroleptics with flatter dose-response curves.

Interactions

Pharmacogenomic + mechanism interactions2 edges

Pharmacogenomic guideline recommendationsCPIC and Dutch Pharmacogenetics Working Group clinical guidelines

Phenotype:CYP3A4 poor metabolizer prefer alternative DPWG 60 / 100Rate

DPWG guideline: Patients who are CYP3A4 poor metabolizers and being treated for depression should be given an alternative drug. Patients being treated for other indications and who are CYP3A4 poor metabolizers should be given a reduced dose of quetiapine. No action is needed for patients who are CYP3A4 intermediate metabolizers. ClinPGx uses CYP3A4 allele nomenclature as defined by PharmVar , while the current version of this guideline issued by the DPWG uses retired allele names. Further details are given on the DPWG curation page .

Phenotype:CYP3A4 intermediate metabolizer prefer alternative DPWG 60 / 100Rate

DPWG guideline: Patients who are CYP3A4 poor metabolizers and being treated for depression should be given an alternative drug. Patients being treated for other indications and who are CYP3A4 poor metabolizers should be given a reduced dose of quetiapine. No action is needed for patients who are CYP3A4 intermediate metabolizers. ClinPGx uses CYP3A4 allele nomenclature as defined by PharmVar , while the current version of this guideline issued by the DPWG uses retired allele names. Further details are given on the DPWG curation page .

Patient experience

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The clinically important interactions for prescribers:

• CYP3A4 inhibitors: major dose-adjustment interaction. Strong inhibitors such as ketoconazole, itraconazole, ritonavir, clarithromycin, and nefazodone produce substantial increases in quetiapine exposure (several-fold). Per the Seroquel label, the quetiapine dose should be reduced to approximately one-sixth of the usual dose when co-administered with a strong CYP3A4 inhibitor; if the inhibitor is discontinued, quetiapine can be retitrated to the prior effective dose. Moderate inhibitors (erythromycin, fluconazole, diltiazem, verapamil, grapefruit juice) require monitoring and lesser dose adjustment.
• CYP3A4 inducers: substantially reduce quetiapine effectiveness. Carbamazepine reduces quetiapine AUC by approximately 80%; phenytoin similarly. Co-administration with strong inducers generally requires substantial dose increase (the FDA label allows increases up to fivefold the usual dose during co-administration). St. John's wort, rifampin, and dexamethasone are other relevant inducers.
• Opioids: respiratory depression risk. Quetiapine is not subject to the 2016 benzodiazepine-opioid boxed warning, but additive CNS and respiratory depression with opioids is a recognized clinical concern; quetiapine-oxycodone is on the Seroquel label's pharmacokinetic interactions list. Use the lowest effective doses when combined; counsel patients about respiratory risk and avoid the combination where possible.
• Alcohol: additive sedation and CNS depression. Counsel patients to avoid alcohol or to limit consumption substantially during quetiapine treatment, particularly early in treatment.
• QT-prolonging medicines: additive QT effect. Caution with concurrent use of class IA and III antiarrhythmics, methadone, several antibiotics (macrolides, fluoroquinolones), antifungals, and other neuroleptics. Consider ECG monitoring when combining QT-prolonging agents.
• Other CNS depressants (benzodiazepines, barbiturates, gabapentinoids, sedating antihistamines, muscle relaxants): additive sedation. Avoid combinations where possible.
• Levodopa and dopamine agonists: pharmacologic antagonism. Quetiapine may reduce the antiparkinsonian effect of levodopa and dopamine agonists in patients with Parkinson disease. Quetiapine is sometimes selected for psychotic symptoms in Parkinson disease because of its low D2 occupancy, but the antagonism remains relevant.
• Antihypertensives: additive hypotension and orthostasis. Particular caution in elderly patients on multiple antihypertensive agents.
• Lithium and divalproex: no clinically significant pharmacokinetic interaction; commonly combined in bipolar disorder.

  Pregnancy and lactation

Quetiapine crosses the placenta in modest amounts (umbilical cord-to-maternal plasma ratio approximately 24%, lower than risperidone or olanzapine). The pregnancy literature on atypical neuroleptics has substantially attenuated earlier concerns about teratogenicity; recent large cohort analyses using active-comparator designs and confounding-by-indication adjustment have found no consistent signal for major congenital malformations with quetiapine specifically. Quetiapine is therefore frequently used in pregnancy when neuroleptic treatment is clinically necessary, both for primary indications such as bipolar disorder and schizophrenia and as a substitute for higher-risk medicines such as valproate.

Third-trimester exposure is associated with transient neonatal symptoms, including extrapyramidal signs, feeding difficulty, respiratory distress, and uncommonly withdrawal, typically resolving within days. Gestational diabetes risk may be modestly elevated by maternal quetiapine; routine glucose screening in pregnancy applies. Breastfeeding while taking quetiapine produces low infant medicine exposure (relative infant dose typically less than 1%), and quetiapine is among the neuroleptics considered compatible with breastfeeding.

For women with bipolar disorder or schizophrenia maintained on quetiapine who become pregnant, continuation is generally preferred to discontinuation because of relapse risk; the medicine's relative safety profile in pregnancy makes the maternal mental health argument straightforward. For women on quetiapine off-label for sleep or anxiety, pregnancy is an appropriate occasion to deprescribe in favor of behavioral interventions or, where pharmacotherapy is required, evidence-based alternatives such as the SSRI sertraline.

Monitoring

Boxed warning: all atypical neuroleptics including quetiapine carry a boxed warning for increased mortality in elderly patients treated for dementia-related psychosis. Quetiapine is not approved for dementia-related psychosis at any age; if used off-label for this indication, the boxed warning applies and should be documented in the chart.

Metabolic monitoring is the dominant ongoing safety task in quetiapine prescribing. The 2004 American Diabetes Association / American Psychiatric Association joint consensus monitoring schedule (developed jointly with the American Association of Clinical Endocrinologists and the North American Association for the Study of Obesity) remains the standard reference:

• Baseline: weight, BMI, waist circumference, blood pressure, fasting glucose or HbA1c, fasting lipid panel, personal and family history of diabetes, dyslipidemia, hypertension, cardiovascular disease.
• Weight and BMI: at baseline, 4, 8, and 12 weeks, then quarterly.
• Blood pressure, fasting glucose or HbA1c, fasting lipids: at baseline, 12 weeks, then at least annually.
• If clinically significant weight gain (more than 5% from baseline), worsening glycemic control, or worsening lipid panel, intensify monitoring and consider switching to a metabolically more favorable agent (aripiprazole, ziprasidone, or lurasidone).

Additional monitoring: assess for extrapyramidal signs at each visit; baseline and annual abnormal involuntary movement scale (AIMS) examination for tardive dyskinesia; baseline ECG in patients with cardiovascular risk factors or on concurrent QT-prolonging medicines; baseline ophthalmologic examination is not routinely recommended (the beagle-cataract concern that initially prompted six-month slit-lamp screening has not been confirmed in human surveillance studies).

For elderly patients on quetiapine: assess fall risk at each visit; monitor for orthostatic hypotension; reassess clinical indication and consider deprescribing at each visit, particularly if the indication is off-label.

Overdose. Quetiapine overdose presents with progressive sedation, hypotension, tachycardia, anticholinergic features (mydriasis, dry mucous membranes, urinary retention, ileus), and at higher doses respiratory depression, QT prolongation, seizures, and coma. Reported survivable ingestions extend to over 30 grams; fatal ingestions have occurred at lower doses, particularly in mixed overdose.

Management is primarily supportive: airway protection, intravenous fluids for hypotension, ECG monitoring with attention to QT and arrhythmias, cardiac monitoring for at least 24 hours in significant ingestions. Activated charcoal may be considered within one hour of ingestion if the airway is protected. Vasopressors (norepinephrine preferred over dopamine, given quetiapine's alpha-1 antagonism) for refractory hypotension. There is no specific antidote. Hemodialysis is not effective owing to the large volume of distribution.

Co-ingestion is the rule rather than the exception in quetiapine overdose; alcohol, benzodiazepines, and opioids substantially worsen prognosis. The widespread availability of quetiapine in homes where it is prescribed off-label for insomnia has contributed to its prominence in suicidal overdose attempts; counseling about safe medicine storage and limited dispense quantities in at-risk patients is appropriate.

Patient counseling

Off-label use: most quetiapine prescriptions are for indications the medicine is not formally approved to treat. If quetiapine has been prescribed for sleep, anxiety, agitation, or PTSD, the patient should understand that the prescribing is off-label, that the evidence base for these indications is modest, that the metabolic and cardiovascular risk profile applies even at low doses, and that evidence-based alternatives exist (cognitive behavioral therapy for insomnia, SSRIs and SNRIs for anxiety, exposure-based therapies for PTSD).

Metabolic risk: counsel patients about weight gain, the risk of new-onset diabetes, and the elevated cardiovascular risk associated with long-term quetiapine use. Encourage weight monitoring at home. Discuss the metabolic monitoring schedule and the rationale for the laboratory testing.

Orthostatic hypotension and fall risk: counsel patients to rise slowly from sitting or lying positions, particularly during the first weeks of treatment and after dose increases. Elderly patients and patients on antihypertensives should be especially careful; falls are a leading cause of quetiapine-related morbidity in older adults.

Sedation and driving: do not drive or operate machinery early in treatment, after any dose increase, or when combining quetiapine with other CNS depressants. Sedation typically peaks 1-2 hours after dosing; evening dosing minimizes daytime sedation but daytime impairment remains common particularly early in treatment.

Alcohol: avoid or limit alcohol during quetiapine treatment; the combination produces additive sedation.

Pregnancy: if pregnancy is planned or discovered, contact the prescriber. For women on quetiapine for bipolar disorder or schizophrenia, continuation is generally preferred over discontinuation. For women on low-dose quetiapine for sleep or anxiety, pregnancy is an appropriate occasion to discuss deprescribing.

Discontinuation: do not stop quetiapine abruptly. Discontinuation symptoms include withdrawal insomnia, anxiety rebound, nausea, and (less commonly) cholinergic rebound; the contemporary deprescribing standard is a hyperbolic taper over weeks to months depending on the duration and dose of treatment.

Suicidal ideation (when used for depression): for quetiapine prescribed for bipolar depression or as an MDD adjunct, the antidepressant-class boxed warning regarding suicidal thoughts and behaviors applies: children, adolescents, and young adults up to age 24 are at elevated risk, particularly during the first 1-2 months of treatment and after dose changes. Report new or worsening suicidal thoughts immediately.

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See also

Olanzapine, Risperidone, Aripiprazole, Clozapine, Lurasidone

References

Summary

Classes

Neuroleptic, Second-generation (atypical) neuroleptic, Dibenzothiazepine, Serotonin-dopamine antagonist

Common uses

• Agitation in the setting of dementia★★★★★★★★★★★★★★★—×
• Anxiety★★★★★★★★★★★★★★★—×
• Bipolar Disorder★★★★★★★★★★★★★★★—×
• Bipolar I Disorder★★★★★★★★★★★★★★★—×
• Insomnia★★★★★★★★★★★★★★★—×

+ 2 more uses →

Pharmacy

Starting dose

25 mg (schizophrenia, immediate-release); 50 mg (bipolar mania, immediate-release); 50 mg (Seroquel XR, schizophrenia or bipolar)

Preparations

25 mg, 50 mg, 100 mg, 200 mg, 300 mg, 400 mg immediate-release tablets; 50 mg, 150 mg, 200 mg, 300 mg, 400 mg extended-release tablets (Seroquel XR)

US FDA Max

800 mg/day

Pill ID

• 25 mg: peach round film-coated tablet
• 50 mg: white round film-coated tablet
• 100 mg: yellow round film-coated tablet
• 200 mg: white round film-coated tablet
• 300 mg: white capsule-shaped film-coated tablet
• 400 mg: yellow capsule-shaped film-coated tablet
• XR tablets: film-coated, varying shapes and colors by strength

Pharmacology

Routes

Oral

Onset

30-60 min (sedation); days to weeks (neuroleptic effect)

Duration

6-8 h (immediate-release); 24 h (extended-release)

Half-life

~6 h (parent compound, immediate-release); ~9-12 h (active metabolite N-desalkylquetiapine, also called norquetiapine)

Bioavailability

Tablet ~100% relative to oral solution; extensive first-pass metabolism

Pregnancy

Pregnancy categories were retired by FDA in 2015. Quetiapine has reassuring active-comparator cohort data without consistent teratogenic signal; among the preferred neuroleptics when treatment is clinically necessary in pregnancy. See pregnancy_details for the full citation set.

Legal status

Prescription only; not a controlled substance

Purported mechanism

Dopamine D2 and serotonin 5-HT2A receptor antagonist Quetiapine acts as an antagonist at dopamine D2 and serotonin 5-HT2A receptors and has substantial activity at histaminergic, adrenergic, and other receptors that contribute to its clinical effects.▲0▼