Quetiapine

Both forms treat schizophrenia in adults and adolescents aged 13–17, acute bipolar I mania in adults and monotherapy mania in ages 10–17, and adult bipolar depressive episodes. Adult mania can be monotherapy or adjunctive to lithium/divalproex; XR also specifically includes mixed episodes. Adult bipolar I maintenance is adjunctive to lithium or divalproex, not an established monotherapy maintenance regimen.

Seroquel XR is labeled as adjunctive therapy to antidepressants for adult major depressive disorder. IR does not have that indication. XR has adult schizophrenia maintenance trial support; IR maintenance schizophrenia efficacy has not been systematically established in controlled trials, despite a maintenance dose row in its label.

Neither form is approved for dementia-related psychosis. Pediatric bipolar depression and pediatric maintenance efficacy are not established. Insomnia-only regimens, other antipsychotic conversions, and compounded liquids are outside this labeled reference.

For schizophrenia at ages 13–17 or bipolar mania monotherapy at ages 10–17, start IR at 25 mg twice daily or XR at 50 mg once daily. Total daily doses on Days 1–5 are 50, 100, 200, 300 and 400 mg. Further IR increases are no greater than 100 mg/day; schizophrenia target/max is 400–800/800 mg/day and mania 400–600/600 mg/day. IR is divided twice daily, sometimes three times daily according to response; XR remains once daily. Pediatric treatment requires comprehensive diagnostic and psychosocial assessment.

Hepatic impairment: start IR 25 mg/day, increase by 25–50 mg/day; start XR 50 mg/day, increase by 50 mg/day, guided by tolerability. Elderly patients: the labels start 50 mg/day with 50 mg/day increments and emphasize slower titration and lower targets. This does not override a more cautious hepatic regimen. Renal adjustment is not required by the PK data, but clinical experience is limited.

IR may be taken with or without food. Take XR once daily, preferably evenings, without food or with a light meal of about 300 calories; swallow whole without splitting, chewing or crushing. A clinician may change established IR to XR at the equivalent total daily dose, with individual adjustments. After more than one week off either form, repeat the initial dosing schedule; shorter interruptions still require advice. Gradual withdrawal is advised; no universal taper is supplied.

Known hypersensitivity to quetiapine or product excipients is contraindicated; anaphylaxis has occurred. Dementia mortality, QT and other major cautions are warnings rather than additional formal contraindications in these selected U.S. labels.

Both selected labels warn of increased mortality with antipsychotics in elderly patients with dementia-related psychosis; quetiapine is not approved for that use. The antidepressant warning addresses increased suicidal thoughts or behaviors in children, adolescents and young adults. Monitor patients of all ages for clinical worsening or suicidality, especially early and during dose changes; involve caregivers.

Common effects include somnolence, dizziness, dry mouth, constipation, weight gain, fatigue and orthostatic symptoms; frequencies vary by indication, age and formulation. IR trials also identify increased ALT. Postmarketing reports include serious cutaneous reactions (SJS/TEN, DRESS, AGEP), myocarditis/cardiomyopathy, severe liver injury, pancreatitis, rhabdomyolysis, SIADH/hyponatremia and intestinal obstruction. Voluntary reports do not define incidence or prove causation.

Reduce either form to one-sixth of the original dose with a potent CYP3A4 inhibitor, such as ketoconazole or ritonavir. On inhibitor discontinuation, the label calls for a six-fold increase back toward the original dose. Dose selection and available strengths require individualized prescribing.

With chronic potent inducer treatment (more than 7–14 days), doses may need to increase up to five-fold according to response and tolerability. Examples include phenytoin, carbamazepine, rifampin and St. John’s wort. When the inducer stops, reduce to the original dose within 7–14 days. These are specialist interaction instructions, not permission to multiply a standard maximum unsupervised.

Avoid alcohol and use caution with other CNS depressants. Avoid medicines known to prolong QT or cause relevant electrolyte disturbances. Additional antimuscarinic medicines raise severe gastrointestinal hypomotility risk; antihypertensives can worsen hypotension. Quetiapine may oppose levodopa or dopamine agonists. Tell urine-drug-screen staff about treatment because results may be affected.

Published epidemiology has not established a drug-associated major birth-defect or miscarriage risk, but this does not establish absence of risk. Balance untreated illness against treatment effects. Third-trimester exposure can cause neonatal extrapyramidal or withdrawal symptoms, including feeding or respiratory difficulty; monitor exposed neonates. A pregnancy registry is available. Quetiapine enters milk in small amounts in limited reports; consider breastfeeding benefits, maternal need and possible infant effects individually.

Schizophrenia use begins at age 13 and mania monotherapy at age 10 in these labels. Pediatric depression and maintenance are not established; monitor pediatric growth/weight, metabolic effects and BP. Older adults have reduced clearance and greater orthostasis or tolerability concerns. The dementia mortality warning applies even when a lower dose is used.

Renal PK data support no dose adjustment, with limited clinical experience. Liver impairment increases exposure and requires formulation-specific lower starts. Increased prolactin may cause menstrual/sexual symptoms and reversible impairment of female fertility; assess clinically rather than assuming every patient develops these effects.

The mechanism in the labeled indications is not fully defined. Dopamine D2 and serotonin 5-HT2A antagonism may contribute. Active norquetiapine also has receptor activity; histamine and adrenergic effects relate to sedation and orthostasis, while muscarinic activity contributes to anticholinergic effects.

IR peaks at about 1.5 hours; XR at about 6 hours. XR once daily has comparable bioavailability to the equivalent IR total dose divided twice daily, but high-fat meals raise XR exposure. Quetiapine is about 83% protein-bound and extensively metabolized via hepatic CYP3A4; less than 1% is excreted unchanged. The selected IR label gives a parent half-life near 6 hours; XR gives about 7 hours and about 12 hours for norquetiapine.

Quetiapine is not a controlled substance in these U.S. labels, but misuse history warrants assessment. Abrupt cessation can produce insomnia, nausea, vomiting and other symptoms; gradual withdrawal and monitoring for illness relapse are advised.

Assess weight, fasting lipids, glucose/diabetes risk, blood pressure, orthostasis, falls and movement symptoms. Check pediatric BP at baseline and periodically. Obtain frequent early CBC for low baseline WBC or prior drug-induced leukopenia. The labels recommend lens examination at initiation or soon after and every 6 months during chronic treatment; measure both TSH and free T4 at baseline and follow-up. Evaluate ECG/electrolytes when QT risk is relevant.

Avoid driving or hazardous tasks until effects are known, avoid alcohol, rise carefully and prevent overheating or dehydration. Report new uncontrolled movements, severe constipation, infection/fever, visual changes or endocrine symptoms. High fever with rigidity/confusion, severe rash, breathing difficulty, fainting or suicidal thoughts require urgent care. Do not stop abruptly or restart an old full dose after a prolonged gap.

Excess dosing can cause profound sedation, coma, hypotension, tachycardia, anticholinergic toxicity and QT abnormalities. Emergency management includes airway support and continuous ECG monitoring; contact Poison Control at 1-800-222-1222. XR overdose can form a gastric pharmacobezoar requiring specialist assessment; no home decontamination or numerical rescue protocol is provided.

Appearance

Peach, round, biconvex, film-coated

Imprint

SEROQUEL and 25 on one side · plain reverse

Example package

NDC 61269-250-10 · bottle of 100

Distributor

H2-Pharma, LLC

Selected IR tablets: 25, 50, 100, 200, 300 and 400 mg. Selected XR tablets: 50, 150, 200, 300 and 400 mg. Strengths are expressed as quetiapine, supplied as fumarate. XR tablets are capsule-shaped with XR plus strength on one side. Generic appearances vary; no injectable or liquid regimen is supplied here.

Both selected prescribing labels specify 25°C with permitted excursions to 15–30°C. Keep medicines away from children and follow the dispensed package. XR must remain intact; do not split, chew or crush it or confuse it with IR.