Atypical antipsychotic (second generation) Pregnancy: Moderate data from exposed pregnancies do not suggest an increased risk of malformations, but a definite conclusion cannot be drawn; use during pregnancy only if benefits justify the potential risks. Neonates exposed in the third trimester are at risk of extrapyramidal and/or withdrawal symptoms — monitor carefully. Excretion into breast milk appears inconsistent.

Quetiapine

Brand names: Seroquel, Atrolak, Brancico

Quetiapine is a second-generation ('atypical') antipsychotic used in schizophrenia, bipolar disorder and as an adjunct in depression; lower doses are widely used for their sedative effect.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: Schizophrenia: usual effective dose 300 to 450 mg/day

Route: Oral

Frequency: Twice daily (once daily at bedtime for major depressive episodes in bipolar disorder)

Max: 750 mg/day (schizophrenia); 800 mg/day (bipolar disorder)

Different dosing schedules exist for each indication. Schizophrenia: administer twice daily; total daily dose 50 mg (Day 1), 100 mg (Day 2), 200 mg (Day 3), 300 mg (Day 4), then titrate to usual effective 300-450 mg/day (range 150-750 mg/day). Moderate-to-severe manic episodes in bipolar disorder: twice daily, 100/200/300/400 mg on Days 1-4, then up to 800 mg/day by Day 6 (increments no greater than 200 mg/day); usual effective 400-800 mg/day. Major depressive episodes in bipolar disorder: once daily at bedtime, 50/100/200/300 mg Days 1-4, recommended 300 mg/day. Preventing recurrence in bipolar disorder: continue effective dose twice daily, range 300-800 mg/day. Elderly: slower titration and lower daily dose (mean plasma clearance reduced 30-50%). Hepatic impairment: start 25 mg/day and increase in 25-50 mg/day increments. Not recommended for use in children and adolescents under 18 years (lack of data). Can be taken with or without food.

Dose adjustments

Renal

Dosage adjustment is not necessary in patients with renal impairment.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

US labelling (FDA)

Reference — US labelling, may differ from UK

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 (2.2) 50 mg once daily at bedtime 300 mg/day 300 mg/day Geriatric Use: Consider a lower starting dose …

Source: US FDA prescribing information (openFDA / DailyMed), label dated 2025-06-27. Accessed 2026-06-12. US dosing and indications can differ from UK practice — use UK sources for prescribing decisions.

Contraindications

Hypersensitivity to the active substance or to any of the excipients
Concomitant administration of cytochrome P450 3A4 inhibitors, such as HIV-protease inhibitors, azole antifungals, erythromycin, clarithromycin and nefazodone

Side effects

Somnolence, dizziness, headache
Dry mouth
Weight gain; elevations in serum triglycerides and total cholesterol (predominantly LDL), decreased HDL cholesterol
Extrapyramidal symptoms
Orthostatic hypotension, tachycardia; QT prolongation (uncommon)
Decreased haemoglobin; withdrawal (discontinuation) symptoms

Interactions

Strong CYP3A4 inhibitors (e.g. ketoconazole, itraconazole, ritonavir, nefazodone, erythromycin, clarithromycin): increase quetiapine exposure — concomitant use of these agents is contraindicated per SPC
Strong CYP3A4 inducers (e.g. phenytoin, carbamazepine, rifampin, St John's wort): decrease quetiapine exposure — dose adjustment may be required
Alcohol and other centrally acting drugs: additive CNS effects; alcohol should be limited

Clinical monograph

How it works

It antagonises dopamine D2 and serotonin 5-HT2A (and other) receptors; its prominent sedation reflects strong histamine H1 blockade.

Prescribing in practice

Metabolic effects (weight gain, dyslipidaemia, raised glucose/diabetes), sedation and postural hypotension are common.
It can prolong the QT interval.
As with all antipsychotics, it increases stroke and mortality risk in older people with dementia — use only where justified.

Monitoring

Monitor weight/BMI, lipids, glucose/HbA1c, blood pressure and (where indicated) ECG.

Counselling the patient

Drowsiness and dizziness on standing are common, especially at first.
Attend your metabolic monitoring (weight, blood tests).
Report fainting or palpitations.

Evidence & guidelines

Recommended across psychotic and mood disorders (NICE NG178/CG185), balanced against metabolic risk.

Reference: NICE CG178; NICE NG185; Maudsley Prescribing Guidelines 14th ed.; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Calculators

Drugs

Olanzapine · Atypical antipsychotic (second generation)

Pathways