NK1 receptor antagonist Pregnancy: No clinical data on exposed pregnancies for fosaprepitant or aprepitant; animal studies did not indicate direct or indirect harmful effects on pregnancy or development, but reproductive toxicity has not been fully characterised. Should not be used during pregnancy unless clearly necessary. Breast-feeding is not recommended during treatment. The efficacy of hormonal contraceptives may be reduced during and for 28 days after administration - use alternative non-hormonal contraception during treatment and for 2 months after the last dose.

Fosaprepitant

Brand names: Ivemend

Fosaprepitant is an intravenous prodrug of aprepitant, a neurokinin-1 (NK1) receptor antagonist, used with other antiemetics to prevent nausea and vomiting associated with moderately and highly emetogenic chemotherapy.

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: 150 mg

Route: Intravenous infusion over 20-30 minutes

Frequency: Single dose on Day 1, started approximately 30 minutes before chemotherapy

SPC §4.2: give in conjunction with a corticosteroid and a 5-HT3 antagonist. Highly emetogenic chemotherapy (adults): fosaprepitant 150 mg intravenously on Day 1 only, with dexamethasone 12 mg orally on Day 1, 8 mg orally on Day 2, then 8 mg orally twice daily on Days 3 and 4, plus a standard dose of a 5-HT3 antagonist on Day 1 (dexamethasone 30 minutes before chemotherapy on Day 1 and in the morning on Days 2-4, with evening doses on Days 3 and 4; the dexamethasone dose already accounts for the interaction). Moderately emetogenic chemotherapy (adults): fosaprepitant 150 mg intravenously plus dexamethasone 12 mg orally and a standard 5-HT3 antagonist dose on Day 1. Must not be given as a bolus injection - always dilute and give as a slow intravenous infusion; do not give intramuscularly or subcutaneously. Elderly (>=65 years) and gender: no dose adjustment. Moderate to severe hepatic impairment: limited or no data - use with caution. Paediatric population: the SPC gives separate weight-based intravenous regimens for patients aged 6 months to 17 years and not less than 6 kg, which differ by age band and by whether a single-day or 3-day (fosaprepitant then oral aprepitant) regimen is used, with different maximum doses and infusion durations (30 minutes for 12 years and over, 60 minutes below 12 years) - no single per-kg figure applies, so verify the exact regimen against SPC §4.2 and a children's formulary. Safety and efficacy below 6 months of age have not been established.

Dose adjustments

Renal

No dose adjustment is necessary for patients with renal impairment (the SPC sentence continues regarding end-stage renal disease but is truncated in the fetched bundle - verify against the full SPC).

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.

Contraindications

Hypersensitivity to the active substance, to polysorbate 80, or to any of the other excipients
Co-administration with pimozide, terfenadine, astemizole or cisapride

Side effects

Hiccups; dyspepsia, constipation, decreased appetite (common with the aprepitant regimen)
Headache (common); dizziness and somnolence (uncommon)
Alanine aminotransferase increased
Fatigue/asthenia
Infusion site reactions including thrombophlebitis, vasculitis and necrosis (mainly with concomitant vesicant chemotherapy)
Immediate hypersensitivity reactions including flushing, erythema, dyspnoea and anaphylaxis/anaphylactic shock during or soon after infusion

Interactions

Pimozide, terfenadine, astemizole, cisapride: co-administration contraindicated
CYP3A4 substrates with a narrow therapeutic range - ciclosporin, tacrolimus, sirolimus, everolimus, alfentanil, ergot alkaloid derivatives, fentanyl, quinidine: use fosaprepitant with caution
Irinotecan: approach concomitant use with particular caution (combination may increase toxicity)
Warfarin (CYP2C9 substrate): monitor INR closely for 14 days after fosaprepitant use in patients on chronic warfarin
Hormonal contraceptives: efficacy may be reduced during and for 28 days after administration - use alternative non-hormonal back-up contraception during treatment and for 2 months afterwards
(§4.5 was truncated in the fetched bundle - the above are from SPC §4.3/§4.4; verify against the full SPC)

Clinical monograph

How it works

It is rapidly converted to aprepitant, which blocks substance P at central NK1 receptors, complementing the action of a 5-HT3 antagonist and a corticosteroid in the antiemetic regimen.

Prescribing in practice

Hypersensitivity and infusion-site reactions can occur, so it must be given as directed and stopped if a serious reaction develops.
It interacts via CYP3A4, increasing exposure to drugs metabolised by this enzyme (including the corticosteroid co-administered) and reducing the efficacy of hormonal contraceptives.
Use it as part of a combination antiemetic regimen rather than as monotherapy, and adjust co-administered corticosteroid as advised.

Monitoring

Monitor for infusion-related and hypersensitivity reactions and review concomitant CYP3A4 substrates for altered effect.

Counselling the patient

Use an additional non-hormonal method of contraception during treatment and for a period afterwards.
Report any rash, flushing or breathing difficulty during the infusion.
This is given alongside your other anti-sickness medicines.

Evidence & guidelines

NK1 antagonist efficacy in chemotherapy-induced nausea and vomiting is supported by randomised controlled trials and reflected in oncology antiemetic guidelines.

Reference: NICE TA313; ESMO antiemetic guidelines; 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

Myasthenia Gravis Activities of Daily Living (MG-ADL) Scale · Neuromuscular

Pathways