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NK1 Receptor Antagonist (Antiemetic) Pregnancy: Avoid — insufficient data

Aprepitant

Brand names: Emend

Adult dose

Dose: PONV prevention: 40 mg oral 3h before anaesthesia induction (single dose). CINV: 125 mg OD on day 1, then 80 mg OD on days 2 and 3.
Route: Oral (PONV); oral (CINV)
Frequency: Single dose (PONV); 3-day course (CINV)
Max: 125 mg/day
Oral NK1 antagonist — fosaprepitant is IV prodrug. For PONV: single 40 mg dose superior to ondansetron 4 mg in several trials. For CINV: triple therapy (NK1 + 5-HT3 + dexamethasone) standard for highly emetogenic chemotherapy.

Paediatric dose

Route: Oral
Frequency: OD (day 1–3 for CINV)
Max: Children ≥12 years: adult doses
Concentration: 40 mg, 80 mg, 125 mg capsules mg/ml
CINV in children ≥12 years: adult dosing. Paediatric CINV (<12 years): fosaprepitant dose by weight (specialist oncology guidance)

Dose adjustments

Renal

No dose adjustment required

Hepatic

Caution in severe hepatic impairment (Child-Pugh C)

Clinical pearls

  • Triple therapy for CINV: NK1 (aprepitant) + 5-HT3 (ondansetron) + dexamethasone = most effective regimen for highly emetogenic chemotherapy (cisplatin-based)
  • Dexamethasone dose: reduce by 50% when used with aprepitant (inhibits its metabolism)
  • OCP interaction: aprepitant may reduce efficacy of combined oral contraceptives — advise barrier contraception for 1 month
  • PONV: aprepitant 40 mg OD > ondansetron for 24h delayed PONV but similar for immediate PONV

Contraindications

  • Concomitant pimozide (CYP3A4 substrate — toxic levels)
  • Terfenadine or astemizole use

Side effects

  • Fatigue
  • Hiccups
  • Headache
  • Constipation
  • Diarrhoea
  • Nausea (paradoxically in some)

Interactions

  • CYP3A4 substrates — aprepitant is moderate CYP3A4 inhibitor (transiently): dexamethasone dose halved when given with aprepitant; warfarin levels reduced (INR may fall — monitor)
  • CYP3A4 inducers (rifampicin) — reduce aprepitant efficacy
  • Oral contraceptives — reduced efficacy (use alternative method 1 month post-course)

Monitoring

  • PONV/CINV response
  • INR if on warfarin
  • CYP3A4 drug levels if relevant

Reference: BNFc; BNF; MASCC/ESMO CINV Guidelines 2016; Scuderi PF (PONV aprepitant trial). Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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