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Atypical antipsychotic (second generation) Pregnancy: Use only if essential. Neonatal effects similar to other antipsychotics.

Quetiapine

Brand names: Seroquel, Atrolak, Brancico

Adult dose

Dose: Schizophrenia: 300–450 mg/day; Bipolar mania: 400–800 mg/day; Depression in bipolar: 50–300 mg/day at night
Route: Oral
Frequency: Twice daily (immediate-release); once daily (extended-release)
Max: 800 mg/day
Schizophrenia (IR): 25 mg BD day 1, 50 mg BD day 2, 100 mg BD day 3, titrate to 300–450 mg/day in divided doses. Bipolar mania: titrate to 400–800 mg/day. Extended-release: once daily, taken without food at night.

Paediatric dose

Route: Oral
Frequency: Twice daily
Max: 600 mg/day (adolescents)
13–17 years (schizophrenia): 25 mg BD day 1, 50 mg BD day 2, 100 mg BD day 3, titrate to 400–600 mg/day. Bipolar mania (10–17 years): 25 mg BD day 1, titrate to 400–600 mg/day.

Dose adjustments

Renal

No dose adjustment required.

Hepatic

Start at 25 mg and increase slowly in hepatic impairment.

Clinical pearls

  • Quetiapine 25–50 mg used off-label for insomnia in many settings — generally discouraged (metabolic risk, no licence)
  • Lens opacity screening: ophthalmology exam at baseline and every 2 years
  • Titrate slowly in elderly (orthostatic hypotension and sedation risk)
  • Metabolic monitoring mandatory: weight, glucose, lipids (same as olanzapine)
  • Extended-release preferred for better patient adherence

Contraindications

  • Hypersensitivity to quetiapine
  • Concomitant CYP3A4 inhibitors (e.g., azole antifungals, macrolides — if at therapeutic dose)

Side effects

  • Sedation (common — dose-dependent)
  • Orthostatic hypotension
  • Weight gain
  • Metabolic syndrome (hyperglycaemia, dyslipidaemia)
  • Dry mouth
  • Constipation
  • QT prolongation
  • Cataracts (long-term — annual eye exams)

Interactions

  • CYP3A4 inhibitors (ketoconazole, clarithromycin) — increase quetiapine levels 5–6×
  • CYP3A4 inducers (carbamazepine, rifampicin) — reduce quetiapine levels
  • CNS depressants — additive sedation
  • Antihypertensives — enhanced hypotension

Monitoring

  • Weight and BMI
  • Fasting glucose and lipids
  • BP
  • ECG (QT)
  • Ophthalmic exam (annual)

Reference: BNFc; BNF; NICE CG178; NICE NG185; Maudsley Prescribing Guidelines 14th ed.. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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