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Atypical (Second-generation) Antipsychotic — Sublingual Pregnancy: Avoid — limited data; animal studies show developmental toxicity. Neonatal EPS risk with third-trimester exposure.

Asenapine

Brand names: Sycrest

Adult dose

Dose: Bipolar I disorder (acute mania — monotherapy or adjunct): 10mg SL BD; can reduce to 5mg BD if 10mg not tolerated. Schizophrenia: 5mg SL BD initially; increase to 10mg SL BD if needed.
Route: Sublingual only — tablet placed under tongue and dissolved (do not swallow whole; do not eat or drink for 10 minutes after)
Frequency: Twice daily
Max: 20mg daily
Sublingual administration is essential — if swallowed, bioavailability drops from ~35% to <2% (extensive first-pass). Must not eat or drink for 10 minutes after each dose. Unique receptor profile: potent 5-HT2A, 5-HT2C, H1, alpha-1, alpha-2 antagonist; D2 antagonist. NICE recommends for acute mania in bipolar disorder. Rapid dissolution under tongue — onset within 15 minutes.

Paediatric dose

Route: Sublingual
Frequency: Twice daily
Max: Not applicable
Not licensed under 18 years in UK. Seek specialist child and adolescent psychiatry opinion.

Dose adjustments

Renal

No dose adjustment required.

Hepatic

Mild-moderate hepatic impairment: no adjustment. Severe hepatic impairment: avoid — significantly increased exposure.

Clinical pearls

  • Sublingual administration is non-negotiable: a study showed swallowed asenapine has <2% bioavailability vs. 35% sublingual — always place under tongue and ensure patient holds saliva for 10 minutes
  • Oral numbness: tongue hypoaesthesia is very common (up to 50% of patients) — counsel at initiation; usually resolves within 1–2 hours per dose but can persist with long-term use
  • Rapid onset: onset within 15 minutes — useful in acute bipolar mania when rapid antimanic effect is needed
  • No oral food/drink restriction for 10 minutes: this is important for patients on diabetes medication requiring post-meal dosing — schedule accordingly

Contraindications

  • Severe hepatic impairment
  • Hypersensitivity to asenapine
  • Dementia with Lewy bodies (antipsychotics may worsen)

Side effects

  • Oral hypoaesthesia (numbness under tongue — very common; usually transient)
  • Somnolence
  • Dizziness
  • Weight gain (moderate — less than olanzapine)
  • Akathisia
  • QTc prolongation (mild)
  • Hyperprolactinaemia (less than risperidone)
  • Oral ulcers (rare — sublingual formulation)

Interactions

  • CYP1A2 inhibitors (fluvoxamine, ciprofloxacin) — increase asenapine levels; reduce dose
  • QT-prolonging drugs — additive
  • Alpha-adrenergic drugs — additive hypotension

Monitoring

  • EPSE assessment (akathisia common)
  • QTc (ECG)
  • Weight and metabolic parameters
  • Oral mucosa inspection
  • Prolactin if symptomatic

Reference: BNFc; BNF 90; NICE CG185 (Bipolar Disorder); Sycrest SPC. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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