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Antiemetics in Oncology

Last updated 31 May 2026 · Oncology clinical guideline

📋 Key Information Summary

📋
  • Chemotherapy-induced nausea and vomiting (CINV) remains one of the most feared treatment-related toxicities; effective prophylaxis is based on the emetogenic risk of the chemotherapy regimen.
  • Emetogenic risk categories — high (HEC, >90%), moderate (MEC, 30–90%), low (<30%) — determine the antiemetic regimen required before the first cycle.
  • The pathophysiology of CINV involves multiple neurotransmitter pathways: serotonin (5-HT₃) in the acute phase, substance P / NK₁ in the delayed phase, and dopamine, histamine, and acetylcholine contributing to refractory symptoms.
  • 5-HT₃ receptor antagonists (ondansetron, granisetron, palonosetron) are the backbone of acute-phase prophylaxis for HEC and MEC.
  • NK₁ receptor antagonists (aprepitant, fosaprepitant) are required for HEC and are recommended for MEC with additional risk factors; they primarily reduce delayed-phase CINV.
  • Dexamethasone is used across all emetogenic risk categories and in both acute and delayed phases; dose and duration vary by risk level.
  • Olanzapine (off-label, TGA-approved for nausea) is increasingly used as a fourth agent for HEC prophylaxis and as first-line for breakthrough CINV.
  • Anticipatory nausea/vomiting occurs before chemotherapy and is best prevented by optimal acute/delayed CINV control; benzodiazepines may be added.
  • Anticipatory CINV occurs in 18–57% of patients after prior poor control and is best managed with behavioural therapies plus lorazepam; it requires distinct prevention from acute/delayed CINV.
  • Rescue therapy for breakthrough CINV should use an agent from a different pharmacological class than those used for prophylaxis.
  • Aboriginal and Torres Strait Islander patients may face barriers including delayed treatment initiation, reduced access to specialist oncology services, and cultural considerations in symptom reporting.
  • PBS-listed agents for CINV include ondansetron (General Benefit), aprepitant (Authority Required), dexamethasone (General Benefit), and metoclopramide (General Benefit).
  • All antiemetic regimens should be initiated before the first dose of chemotherapy and continued for the full duration of the emetic risk period (typically 2–4 days for HEC).
  • Patients should be counselled on expected CINV timeline, adherence to delayed-phase medications, and when to seek medical review for persistent symptoms.

Introduction & Australian Epidemiology

Chemotherapy-induced nausea and vomiting (CINV) is one of the most distressing and feared side-effects of cancer treatment. Despite major advances in antiemetic pharmacology over the past three decades, CINV continues to affect a substantial proportion of patients, impairing quality of life, nutritional status, treatment adherence, and functional capacity.

In Australia, an estimated 150,000 new cancer diagnoses are made annually (Australian Institute of Health and Welfare, 2023). The majority of patients receiving cytotoxic chemotherapy — whether as adjuvant, neoadjuvant, or palliative treatment — will require structured antiemetic prophylaxis. Without adequate prevention, highly emetogenic regimens such as cisplatin-based chemotherapy produce nausea and vomiting in over 90% of untreated patients.

The management of CINV is guided by emetogenic risk stratification of the chemotherapy agent(s) being administered. The ASCO (American Society of Clinical Oncology), NCCN (National Comprehensive Cancer Network), and MASCC/ESMO (Multinational Association of Supportive Care in Cancer / European Society for Medical Oncology) guidelines, as adapted in Australian practice, classify regimens as high (HEC), moderate (MEC), low, or minimally emetogenic. The antiemetic regimen — typically combining serotonin (5-HT₃) receptor antagonists, corticosteroids, NK₁ receptor antagonists, and in some cases olanzapine — is selected accordingly.

Australian oncology practice follows evidence-based protocols consistent with these international guidelines, supplemented by the Cancer Council Australia clinical guidelines, eviQ protocols, and institutional supportive care pathways. The Pharmaceutical Benefits Scheme (PBS) provides subsidised access to key antiemetic agents, ensuring that evidence-based prophylaxis is accessible across metropolitan, regional, and remote settings.

This guideline provides a comprehensive overview of CINV pathophysiology, the major antiemetic drug classes used in oncology, emetogenic risk stratification, prophylaxis protocols for HEC and MEC, breakthrough and refractory CINV management, and special population considerations relevant to Australian clinical practice.

Pathophysiology of CINV

Understanding the pathophysiology of CINV is essential for rational antiemetic prescribing. Nausea and vomiting are mediated by a complex interplay of neurotransmitter pathways, peripheral and central nervous system signalling, and psychosocial factors.

Phases of CINV

Phase Timing Primary Mechanism Key Mediator
Acute 0–24 hours post-chemotherapy Peripheral (enterochromaffin cells) → vagal afferents → area postrema Serotonin (5-HT₃)
Delayed 24 hours – 5 days post-chemotherapy Central (substance P / NK₁ receptors in NTS and AP) + ongoing peripheral inflammation Substance P (NK₁)
Anticipatory Before chemotherapy administration Conditioned response; prior poor CINV control → anxiety pathway Dopamine, anxiety circuits
Breakthrough Despite prophylactic antiemetics Incomplete blockade of emetogenic pathways; patient-specific factors Multiple (dopamine, histamine, muscarinic)
Refractory Failure of rescue therapy in subsequent cycles Progressive desensitisation, tumour-related factors, medication interactions Multiple

Central and Peripheral Pathways

The vomiting centre (VC) in the medulla oblongata integrates signals from three key afferent sources:

  • Area postrema (chemoreceptor trigger zone, CTZ): Located in the floor of the fourth ventricle, the CTZ lies outside the blood–brain barrier and is directly exposed to circulating chemotherapy agents and their metabolites. It is rich in 5-HT₃, NK₁, and dopamine (D₂) receptors. Activation of the CTZ is a primary driver of acute-phase CINV.
  • Vagal and glossopharyngeal afferents: Chemotherapy agents trigger the release of serotonin from enterochromaffin cells in the gastrointestinal mucosa. Serotonin activates 5-HT₃ receptors on vagal afferent neurons, transmitting signals to the nucleus tractus solitarius (NTS) and CTZ. This peripheral pathway is the dominant mechanism in acute CINV (0–24 hours).
  • Vestibular system: Contributes to motion-related nausea and may exacerbate CINV in patients with pre-existing vestibular dysfunction. Histamine (H₁) and muscarinic (M₃) receptors in the vestibular apparatus mediate this pathway.

Neurotransmitter Receptors Involved

🧠
5-HT₃ Receptors
Serotonin · Acute phase
Location CTZ, NTS, vagal afferents, GI enterochromaffin cells
Role Primary mediator of acute CINV (0–24 h). Chemotherapy causes release of serotonin from gut enterochromaffin cells, activating peripheral and central 5-HT₃ receptors.
🧠
NK₁ Receptors
Substance P · Delayed phase
Location NTS, CTZ, gastrointestinal tract
Role Primary mediator of delayed CINV (24 h – 5 days). Substance P release is sustained and less responsive to 5-HT₃ blockade alone.
🧠
D₂ Receptors
Dopamine · CTZ activation
Location CTZ, NTS
Role Contributes to acute and breakthrough CINV. Target of metoclopramide, prochlorperazine, and haloperidol.
🧠
H₁ / M₃ Receptors
Histamine / Muscarinic · Vestibular
Location Vestibular system, NTS
Role Contribute to motion-related and anticipatory nausea. Target of cyclizine and hyoscine.

Corticosteroid Mechanism

Dexamethasone has a broad antiemetic mechanism, likely through inhibition of prostaglandin synthesis, reduction of peritumoural and peritoneal inflammation, modulation of serotonin release, and central effects on glucocorticoid receptors in the NTS. It is synergistic with both 5-HT₃ and NK₁ antagonists and is a cornerstone of CINV prophylaxis across all emetogenic risk categories.

⚠️
Clinical Pearl: The distinct pathophysiology of acute (5-HT₃-mediated) and delayed (NK₁-mediated) CINV explains why single-agent antiemetic prophylaxis is insufficient for high emetogenic chemotherapy. Combination regimens targeting multiple pathways achieve superior complete response rates.

5-HT₃ Receptor Antagonists

Serotonin (5-HT₃) receptor antagonists are the foundation of acute-phase CINV prophylaxis. They block 5-HT₃ receptors in the CTZ, NTS, and on vagal afferent neurons, preventing the serotonin-mediated emetic signal triggered by chemotherapy agents. All 5-HT₃ antagonists are considered therapeutically equivalent for acute CINV prevention, with the exception of palonosetron, which has a distinct pharmacokinetic profile enabling single-dose coverage of both acute and delayed phases.

Ondansetron (Zofran®)

💊
Ondansetron
Zofran® · Ondemet® · Generic · 5-HT₃ antagonist
Adult dose (HEC) 8 mg IV/PO 30 min pre-chemotherapy, then 8 mg PO/IV 8-hourly for 1–2 days (or 16 mg IV single dose with dexamethasone)
Adult dose (MEC) 8 mg IV/PO single dose pre-chemotherapy; may repeat 8 mg PO 12-hourly for 1–2 days
Paediatric dose 0.15 mg/kg IV (max 8 mg) pre-chemotherapy; may repeat q8h for 1–2 days
Route IV, oral, orally disintegrating tablet (ODT), sublingual
Renal adjustment No adjustment required
Hepatic adjustment Max 8 mg/day in severe hepatic impairment (Child-Pugh C)
Key side effects Constipation (most common), headache, transient QTc prolongation
PBS status ✔ PBS General Benefit
⚠️
QTc caution: Ondansetron can prolong the QTc interval. Use with caution in patients with congenital long QT syndrome, hypokalaemia, hypomagnesaemia, or concurrent QTc-prolonging agents. Consider ECG monitoring in high-risk patients. Avoid doses >16 mg IV as a single bolus.

Granisetron (Kytril®)

💊
Granisetron
Kytril® · Sancuso® (patch) · Generic · 5-HT₃ antagonist
Adult dose (IV) 1 mg IV over 5 min, 30 min pre-chemotherapy; may repeat q12h for up to 5 days
Adult dose (oral) 2 mg PO once daily or 1 mg PO BD, starting pre-chemotherapy
Transdermal patch 3.1 mg/24 h patch applied 24–48 h pre-chemotherapy; worn for up to 7 days
Paediatric dose 10–40 μg/kg IV (max 1 mg) pre-chemotherapy
Renal / hepatic No dose adjustment required
Key side effects Constipation, headache. Lower QTc risk than ondansetron.
PBS status ✔ PBS General Benefit

Palonosetron (Aloxi®)

💊
Palonosetron
Aloxi® · 5-HT₃ antagonist (second-generation)
Adult dose 0.25 mg IV over 30 sec, 30 min pre-chemotherapy. Single dose covers acute + delayed phases (4–5 days).
Advantage Longest half-life (~40 h). Superior efficacy in delayed phase compared with first-generation 5-HT₃ antagonists. Receptor binding affinity 30× higher than ondansetron.
Key side effects Headache, constipation. Minimal QTc effect at recommended dose.
PBS status ⚠ PBS Restricted Benefit — Authority Required for HEC

5-HT₃ Antagonist Selection — Clinical Considerations

  • Equivalence: Ondansetron and granisetron are considered interchangeable for acute-phase CINV prevention. Cost and availability at the institution typically determine choice.
  • Palonosetron advantage: Preferred when single-dose convenience is desired or when additional delayed-phase coverage is needed without adding an NK₁ antagonist (e.g., MEC regimens).
  • Transdermal granisetron: Useful for patients with swallowing difficulty, persistent vomiting precluding oral intake, or adherence concerns with multi-day oral regimens.
  • QTc considerations: If the patient is on other QTc-prolonging chemotherapy (e.g., anthracyclines, arsenic trioxide), granisetron or palonosetron may be preferred over ondansetron.
  • Constipation management: Prophylactic laxatives (e.g., macrogol, docusate + senna) should be co-prescribed with 5-HT₃ antagonists, particularly in patients already at risk.

NK₁ Receptor Antagonists

NK₁ receptor antagonists block substance P binding at NK₁ receptors in the NTS and CTZ. They are primarily effective against delayed-phase CINV and are synergistic with 5-HT₃ antagonists and dexamethasone. NK₁ antagonists are a required component of prophylaxis for highly emetogenic chemotherapy (HEC) and are recommended for select moderate-risk regimens.

Aprepitant (Emend®)

💊
Aprepitant
Emend® · Generic · NK₁ receptor antagonist
Adult dose (HEC) 125 mg PO on Day 1 (1 h pre-chemotherapy), then 80 mg PO on Days 2 and 3
Paediatric dose ≥12 years: same as adult. <12 years: 3 mg/kg PO (max 125 mg) Day 1, 2 mg/kg (max 80 mg) Days 2–3
Route Oral capsules
Renal adjustment No adjustment required
Hepatic adjustment No adjustment for mild–moderate impairment. Limited data in severe impairment.
Key drug interactions CYP3A4 substrate and moderate inhibitor. ↑ Warfarin (check INR Days 7–10). ↓ Effectiveness of hormonal contraceptives (alternative contraception required during and for 1 month after). Use caution with docetaxel, vinca alkaloids, and other CYP3A4-metabolised agents.
Side effects Fatigue, hiccups, constipation, mild transaminase elevation
PBS status ⚠ PBS Authority Required — HEC prophylaxis

Fosaprepitant (Emend IV®)

💊
Fosaprepitant
Emend IV® · NK₁ receptor antagonist (prodrug of aprepitant)
Adult dose 150 mg IV on Day 1 only (30 min infusion, 30 min pre-chemotherapy). Replaces oral aprepitant 3-day regimen.
Advantage Single-dose IV convenience. Suitable when oral intake is unreliable or patient preference.
Key side effects Infusion-site reactions (pain, erythema), fatigue, headache
PBS status ⚠ PBS Authority Required — HEC prophylaxis
⚠️
CYP3A4 interaction alert: Aprepitant/fosaprepitant is a moderate CYP3A4 inhibitor. Concurrent use with pimozide, terfenadine, astemizole, or cisapride is contraindicated. Dose adjustment of warfarin (monitor INR), dexamethasone (reduce dose by 50% on Days 2–4 when used with aprepitant), and CYP3A4-metabolised chemotherapy may be required. Hormonal contraceptive efficacy is reduced — advise barrier contraception during treatment and for 1 month post-treatment.

Emetogenic Risk Stratification

Anti emetic prophylaxis is determined by the emetogenic risk of the chemotherapy regimen when administered intravenously to patients who have not received prior chemotherapy and are not receiving concurrent radiation to the upper abdomen or cranium. Risk categories are based on the proportion of untreated patients expected to experience emesis.

Minimal
<10% Risk
Bleomycin, busulfan (low-dose), cladribine, fludarabine, gemcitabine, rituximab, trastuzumab, vinblastine, vincristine, vinorelbine
Setting: Pre-chemo assessment; no routine prophylaxis or PRN
Low
10–30% Risk
Bortezomib, capecitabine, docetaxel, etoposide, fluorouracil (bolus), gemcitabine (some regimens), irinotecan, methotrexate, paclitaxel, pemetrexed, temozolomide
Setting: Day-case / ambulatory; single-agent antiemetic
Moderate (MEC)
30–90% Risk
Carboplatin (AUC ≥4), cyclophosphamide (<1500 mg/m²), doxorubicin, epirubicin, ifosfamide (<2 g/m²), irinotecan/platinum combinations, oxaliplatin
Setting: Day-case / ambulatory; combination antiemetics required
High (HEC)
>90% Risk
AC regimen (doxorubicin + cyclophosphamide), carboplatin (AUC ≥4, in combination), carmustine (>250 mg/m²), cisplatin (all doses), cyclophosphamide (≥1500 mg/m²), dacarbazine, ifosfamide (≥2 g/m²), mechlorethamine, streptozocin
Setting: Tertiary oncology centre; triple/quadruple antiemetic regimen
ℹ️
Key rule: Carboplatin AUC ≥4 is classified as HEC in current ASCO/MASCC guidelines (2023 update), reflecting evidence that these doses produce >90% emesis without adequate prophylaxis. Carboplatin AUC <4 is classified as MEC.

Additional Patient-Level Risk Factors for CINV

  • Female sex (OR 2.0–3.5)
  • Age <50 years
  • History of motion sickness or morning sickness
  • History of low alcohol intake (<5 standard drinks/week — associated with lower emesis threshold)
  • Prior CINV in earlier chemotherapy cycles
  • Anxiety or anticipatory nausea
  • Concurrent opioid use (can both cause and worsen nausea)

Patients with ≥2 risk factors should receive escalated prophylaxis (e.g., consider adding an NK₁ antagonist to MEC regimens, or adding olanzapine to HEC regimens).

Prophylaxis Protocols

The following protocols reflect current evidence-based Australian practice for CINV prophylaxis based on emetogenic risk category. All antiemetics should be administered before the first dose of chemotherapy, with delayed-phase agents continued for the prescribed duration.

High Emetogenic Chemotherapy (HEC) — Triple / Quadruple Regimen

✅
Standard of care for HEC (ASCO/MASCC 2023): Four-drug regimen — NK₁ antagonist + 5-HT₃ antagonist + dexamethasone + olanzapine — is recommended. Three-drug regimen (without olanzapine) remains acceptable if olanzapine is contraindicated or unavailable.

Option A — Four-Drug Regimen (Preferred)

Day Agent Dose Route
Day 1 Aprepitant 125 mg PO Oral, 1 h pre-chemo
Ondansetron 8–16 mg IV (or 8 mg PO) IV/PO, 30 min pre-chemo
Dexamethasone 12 mg PO/IV 30 min pre-chemo
Olanzapine 10 mg PO Evening of Day 1 (after chemo)
Day 2 Aprepitant 80 mg PO Morning
Dexamethasone 8 mg PO Morning (reduced dose when combined with aprepitant)
Olanzapine 10 mg PO Bedtime
Days 3–4 Dexamethasone 8 mg PO daily Morning
Olanzapine 10 mg PO daily Bedtime
⚠️
Olanzapine caution: Monitor for excessive sedation, particularly in elderly patients (≥70 years) and those on other sedating agents. Dose-reduce to 5 mg in elderly or frail patients. Olanzapine is PBS-listed as General Benefit for nausea/emesis (off-label use for CINV is widespread in Australian oncology practice).

Option B — Three-Drug Regimen (Alternative)

Day Agent Dose
Day 1 Aprepitant 125 mg PO + Ondansetron 8–16 mg IV + Dexamethasone 12 mg PO/IV All pre-chemotherapy
Day 2 Aprepitant 80 mg PO + Dexamethasone 8 mg PO Morning
Days 3–4 Dexamethasone 8 mg PO daily Morning

Moderate Emetogenic Chemotherapy (MEC) — Dual / Triple Regimen

Component Day 1 Days 2–3
5-HT₃ antagonist Ondansetron 8 mg IV/PO pre-chemo 8 mg PO daily (optional)
Dexamethasone 8 mg PO/IV pre-chemo 8 mg PO daily (optional)
± NK₁ antagonist Aprepitant 125 mg PO if high-risk MEC or patient risk factors present Aprepitant 80 mg PO Days 2–3
ℹ️
Palonosetron alternative for MEC: Palonosetron 0.25 mg IV single dose (Day 1) + dexamethasone 8 mg Day 1 may be sufficient for MEC without the need for delayed-phase ondansetron or NK₁ antagonist, due to palonosetron's long half-life and sustained receptor binding.

Low / Minimally Emetogenic Chemotherapy

  • Low emetogenic risk: Dexamethasone 4–8 mg PO/IV single dose pre-chemotherapy, or ondansetron 8 mg PO pre-chemotherapy. PRN rescue antiemetics on subsequent days.
  • Minimal emetogenic risk: No routine prophylaxis. Offer PRN antiemetics (e.g., metoclopramide 10 mg PO TDS or prochlorperazine 5 mg PO TDS as needed).

Oral Chemotherapy Agents

Oral anti-cancer medications have variable emetogenicity. Temozolomide, capecitabine (lower doses), and targeted therapies are generally low risk, while oral cyclophosphamide and oral etoposide carry moderate risk. Antiemetic prophylaxis should be prescribed based on the specific agent's emetogenic classification, not route of administration.

Breakthrough & Refractory CINV Management

Breakthrough CINV is defined as nausea or vomiting occurring despite appropriate prophylactic antiemetic therapy. It occurs in approximately 30–50% of patients receiving HEC and 10–30% receiving MEC. Refractory CINV is defined as failure of rescue therapy in subsequent cycles after an initial breakthrough episode.

⚠️
Key principle: Rescue antiemetic therapy should use an agent from a different pharmacological class than those used in the prophylactic regimen. If the patient received a 5-HT₃ antagonist + dexamethasone + NK₁ antagonist prophylaxis, rescue options include dopamine antagonists, olanzapine, benzodiazepines, or cannabinoids.

Breakthrough CINV — Stepwise Approach

1
Ensure prophylaxis was adequate
Review adherence to delayed-phase antiemetics (aprepitant Days 2–3, dexamethasone Days 2–4). Assess for drug interactions. Consider escalating prophylaxis in the next cycle.
2
First-line rescue
Olanzapine 10 mg PO nocte (if not already prescribed) — most effective rescue agent. Alternatively, metoclopramide 10–20 mg PO/IV q6–8h or prochlorperazine 5–10 mg PO/IV q6–8h.
3
Second-line rescue
Haloperidol 0.5–1 mg PO/IV q8h (dopamine antagonist). Lorazepam 0.5–1 mg SL/PO q6h for anxiety-predominant nausea. Cyclizine 50 mg PO/IV q8h for vestibular component.
4
Refractory / complex cases
Consider nabilone (synthetic cannabinoid — limited PBS availability, Authority Required), levomepromazine (methotrimeprazine) 6.25–12.5 mg PO/SC, or specialist palliative care / oncology review. Continuous SC infusion of antiemetics via syringe driver may be required.

Rescue Antiemetic Agents

💊
Metoclopramide
Maxolon® · D₂ antagonist / prokinetic
Dose 10–20 mg PO/IV q6–8h (max 0.5 mg/kg/day IV). No duration >5 days without specialist review.
Caution Extrapyramidal symptoms (dystonia, akathisia), particularly in young adults. Avoid in bowel obstruction.
PBS status ✔ PBS General Benefit
💊
Prochlorperazine
Stemetil® · D₂ antagonist (phenothiazine)
Dose 5–10 mg PO q6–8h, or 12.5 mg IM/IV, or 25 mg PR q12h
Caution Sedation, extrapyramidal effects, postural hypotension
PBS status ✔ PBS General Benefit
💊
Lorazepam
Ativan® · Benzodiazepine
Dose 0.5–1 mg SL/PO q6–8h PRN. Also used 0.5–1 mg PO nightly for anticipatory CINV/anxiety.
Role Adjunctive rescue agent; most useful for anticipatory nausea and anxiety-predominant symptoms. Not effective as sole antiemetic.
PBS status ✔ PBS General Benefit
💊
Haloperidol
Serenace® · D₂ antagonist (butyrophenone)
Dose 0.5–1 mg PO/IV q8h. Also available as 2–5 mg SC injection.
Role Effective rescue antiemetic, especially for opioid-related and bowel obstruction nausea.
PBS status ✔ PBS General Benefit

Anticipatory CINV

Anticipatory nausea/vomiting occurs in 18–57% of patients after the first chemotherapy cycle and is triggered by environmental cues (sights, smells, sounds of the treatment setting) in patients who experienced poor CINV control previously. It is primarily a conditioned anxiety response rather than a pharmacological problem.

  • Prevention: Optimal antiemetic prophylaxis in Cycles 1–2 is the most effective strategy to prevent anticipatory CINV.
  • Treatment: Lorazepam 0.5–1 mg PO the night before and morning of chemotherapy. Behavioural therapies (systematic desensitisation, progressive muscle relaxation, guided imagery) may be beneficial.
  • Non-pharmacological: Distraction techniques, acupuncture (limited evidence), music therapy. Changing the treatment environment (time, room, nursing staff) may reduce conditioned responses.

Monitoring

Monitoring of CINV control and antiemetic side effects should be systematic across all chemotherapy cycles to enable timely regimen adjustment.

  • Assess CINV at each cycle: Document the severity, timing (acute vs delayed), and duration of nausea and vomiting in every cycle. Use validated tools such as the MASCC Antiemesis Tool (MAT) or the National Cancer Institute Common Terminology Criteria for Adverse Events (CTCAE) grading.
  • Cycle-to-cycle adjustment: If complete response (no emesis, no rescue antiemetics) is achieved, continue the same regimen. If breakthrough CINV occurred, escalate the prophylactic regimen in the next cycle (e.g., add olanzapine, add NK₁ antagonist, or substitute palonosetron).
  • Sedation assessment: If olanzapine is prescribed, assess sedation level before and after dosing. Use a validated sedation scale (e.g., Richmond Agitation–Sedation Scale). Dose-reduce or discontinue if excessive sedation interferes with function.
  • Constipation: Monitor bowel function, particularly in patients receiving 5-HT₃ antagonists and/or opioids. Initiate prophylactic laxatives (macrogol, docusate + senna).
  • QTc monitoring: Baseline and periodic ECG if ondansetron is used in combination with other QTc-prolonging agents, or in patients with cardiac risk factors.
  • Blood glucose: Monitor glucose in diabetic patients receiving dexamethasone, as corticosteroid-induced hyperglycaemia is common.
  • Drug interactions: At each cycle, review new medications and check for CYP3A4 interactions with aprepitant/fosaprepitant.
  • Oral intake and weight: Assess nutritional status if CINV is persistent. Consider dietitian referral and antiemetic regimen review if weight loss >5% occurs.

Special Populations

🤰 Pregnancy
Ondansetron
Category B1. Generally considered safe in pregnancy. Limited data on first-trimester use — discuss risks/benefits. Most commonly used 5-HT₃ antagonist in pregnancy-associated nausea.
Dexamethasone
Category C. Use the minimum effective dose and duration. Avoid prolonged courses due to risk of cleft palate (first trimester) and adrenal suppression (late pregnancy).
Aprepitant
Category B3. Limited pregnancy data. Use only if benefits clearly outweigh risks and alternatives are inadequate.
Metoclopramide
Category A (TGA). Extensively used in pregnancy. Avoid prolonged use (>5 days) due to extrapyramidal risk.
👶 Paediatrics
Ondansetron
0.15 mg/kg IV (max 8 mg) pre-chemotherapy, then q8h. ODT formulation useful for children unable to swallow tablets.
Granisetron
10–40 μg/kg IV (max 1 mg) pre-chemotherapy. Well-tolerated in paediatric oncology.
Aprepitant
≥12 years: adult dosing. <12 years: 3 mg/kg PO (max 125 mg) Day 1, 2 mg/kg (max 80 mg) Days 2–3.
Olanzapine
Limited paediatric data. Use with caution; consider 2.5–5 mg in adolescents if standard regimen fails.
👴 Elderly (≥70 years)
Olanzapine
Dose-reduce to 5 mg. Increased risk of sedation, falls, postural hypotension, and confusion. Monitor closely.
Dexamethasone
May worsen hyperglycaemia, insomnia, and agitation. Consider dose reduction and close glucose monitoring.
5-HT₃ antagonists
No dose adjustment required but monitor for constipation and QTc prolongation.
🫘 Renal Impairment
Ondansetron / Granisetron
No dose adjustment required. Safe in dialysis patients.
Aprepitant
No dose adjustment required for mild–severe renal impairment.
Dexamethasone
No renal adjustment. Monitor fluid status and electrolytes in patients with CKD.
Metoclopramide
Reduce dose by 50% in eGFR <15 mL/min due to accumulation and extrapyramidal risk.
🫁 Hepatic Impairment
Ondansetron
Max 8 mg/day in severe hepatic impairment (Child-Pugh C).
Aprepitant
Limited data in severe hepatic impairment. Use with caution.
Dexamethasone
Metabolised hepatically. Monitor for excessive corticosteroid effects in Child-Pugh B–C.
🛡️ Immunocompromised
General considerations
No specific antiemetic contraindications in immunocompromised patients. CINV control is critical to maintain oral intake, medication adherence, and quality of life during intensive treatment.
Steroid interactions
Dexamethasone may interact with antifungal agents (e.g., itraconazole, posaconazole) — monitor corticosteroid levels and adjust accordingly. Consult pharmacy for interaction checks.

🇦🇹 Aboriginal and Torres Strait Islander Health Considerations

Aboriginal and Torres Strait Islander Health

Aboriginal and Torres Strait Islander Australians experience a higher cancer burden, later-stage diagnosis, and reduced access to timely, culturally safe oncology care compared with non-Indigenous Australians. Effective CINV management must account for these disparities.

Cancer incidence & mortality
ATSI peoples have 1.3× higher cancer incidence and 1.6× higher cancer mortality than non-Indigenous Australians (AIHW, 2023). Lung, bowel, breast, and liver cancers are among the most common.
Remote & regional access
Many ATSI patients receive chemotherapy in regional centres or travel long distances for treatment. Ensuring adequate oral antiemetic supply (particularly delayed-phase agents like aprepitant Days 2–3 and dexamethasone Days 2–4) is critical, as pharmacy access may be limited.
Cultural safety
Nausea and vomiting may be described using culturally specific language. Use Aboriginal Health Workers / Liaison Officers to facilitate symptom assessment. Acknowledge cultural practices around illness and healing.
Health literacy
Provide antiemetic education using plain language, visual aids, and Aboriginal interpreter services where required. Emphasise the importance of completing the full antiemetic course (particularly delayed-phase medications).
Medication adherence
Adherence to delayed-phase antiemetics (often home-based on Days 2–4) may be lower due to travel, housing instability, or reduced follow-up. Consider single-dose IV alternatives (fosaprepitant Day 1) or transdermal granisetron patch to simplify regimens.
Teleoncology
Teleoncology services (e.g., Royal Flying Doctor Service, Queensland Teleoncology) enable remote antiemetic prescribing review and CINV assessment. Ensure telehealth platforms are accessible and culturally appropriate.
Comorbid burden
Higher rates of renal impairment, diabetes, and cardiovascular disease in ATSI populations may influence antiemetic selection (e.g., dexamethasone and glycaemic control, QTc considerations with ondansetron).
Continuity of care
Ensure CINV outcomes are documented and communicated across treatment settings. Use shared care models involving Aboriginal Community Controlled Health Organisations (ACCHOs) for supportive care and follow-up.

📚 References

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  2. 2. Roila F, Molassiotis A, Herrstedt J, et al. 2016 MASCC/ESMO guideline update for the prevention of chemotherapy- and radiotherapy-induced nausea and vomiting. Ann Oncol. 2016;27(suppl 5):v119–v133.
  3. 3. Navari RM, Qin R, Ruddy KJ, et al. Olanzapine for the prevention of chemotherapy-induced nausea and vomiting. N Engl J Med. 2016;375(2):134–142.
  4. 4. Jordan K, Gralla R, Jahn F, Molassiotis A. International antiemetic guidelines on chemotherapy induced nausea and vomiting (CINV): Content and implementation in daily routine practice. Eur J Pharmacol. 2014;722:197–202.
  5. 5. Australian Institute of Health and Welfare (AIHW). Cancer in Australia 2023. Canberra: AIHW; 2023.
  6. 6. Cancer Council Australia. Clinical practice guidelines for the prevention, early detection and management of colorectal cancer. Sydney: Cancer Council Australia; 2017 (updated 2023).
  7. 7. eviQ Cancer Treatments Online. Antiemetic protocols. Cancer Institute NSW. Available at: https://www.eviq.org.au. Accessed 2024.
  8. 8. National Health and Medical Research Council (NHMRC). Chemotherapy induced nausea and vomiting: prevention and treatment. Canberra: NHMRC; 2018.
  9. 9. Herrstedt J, Clark-Snow R, Ruhlmann CH, et al. 2023 MASCC and ESMO guideline update for the prevention of chemotherapy- and radiotherapy-induced nausea and vomiting. ESMO Open. 2023;8(6):102039.
  10. 10. Pharmaceutical Benefits Scheme (PBS). Schedule of Pharmaceutical Benefits. Australian Government Department of Health. Available at: https://www.pbs.gov.au. Accessed 2024.
  11. 11. Australian Commission on Safety and Quality in Health Care (ACSQHC). National Safety and Quality Health Service Standards. 2nd ed. Sydney: ACSQHC; 2017 (updated 2021).
  12. 12. Glaus A, Knipping C, Morant R, et al. Chemotherapy-induced nausea and vomiting in routine practice: a European prospective observational study. Support Care Cancer. 2004;12(10):702–709.
  13. 13. Molassiotis A, Aapro M, Dicato M, et al. Evaluation of risk factors predicting chemotherapy-related nausea and vomiting: results from a European prospective observational study. J Pain Symptom Manage. 2014;47(5):839–848.
  14. 14. Schwartzberg L, Barbour SY, Morrow GR, et al. Pooled analysis of phase III clinical studies of palonosetron versus ondansetron, dolasetron, and granisetron in the prevention of chemotherapy-induced nausea and vomiting (CINV). Support Care Cancer. 2014;22(2):469–477.
  15. 15. Aboriginal and Torres Strait Islander Health Performance Framework. Cancer (measure 1.08). Australian Institute of Health and Welfare; 2023.
for PBS-listed medicines at participating pharmacies.
Cultural safety
Engagement with Aboriginal Community Controlled Health Organisations (ACCHOs) is essential. Cultural safety training for non-Indigenous clinicians, use of Aboriginal Health Workers and Liaison Officers, and incorporation of traditional healing practices alongside Western medicine improve treatment adherence and outcomes. Avoidance of eye contact, respect for gender-sensitive examination practices, and understanding of sorry business protocols are critical elements of culturally safe care.
Medication adherence
Complex DMARD regimens with frequent monitoring requirements present adherence challenges. Long-acting depot injections (e.g., methotrexate SC) may improve adherence compared to oral regimens. Community pharmacy partnerships through the Indigenous Pharmacy Programmes improve medication management.
Specific conditions
Rheumatic heart disease (RHD) requires secondary prophylaxis with benzathine penicillin G (BPG) 1.2 MU IM every 3–4 weeks for a minimum of 10 years or until age 21 (whichever is longer). RHD registers (e.g., NT RHD Register) facilitate recall and follow-up. The Australian RHD Endgame Strategy targets elimination by 2031.
Referral pathways
Referral through ACCHOs and Aboriginal Hospital Liaison Officers (AHLOs) improves engagement. The Specialist Outreach Assistance Programme provides funded specialist visits to remote communities. NT, WA, and QLD have specific rheumatology outreach programmes targeting Indigenous communities.

📚 References

  1. 1. Australian Institute of Health and Welfare (AIHW). Autoimmune disease in Australia. Cat. no. PHE 312. Canberra: AIHW; 2023.
  2. 2. Fraenkel L, Bathon JM, England BR, et al. 2021 American College of Rheumatology guideline for the treatment of rheumatoid arthritis. Arthritis Care Res. 2021;73(7):924–939.
  3. 3. Fanouriakis A, Kostopoulou M, Alber K, et al. 2019 update of the EULAR recommendations for the management of systemic lupus erythematosus. Ann Rheum Dis. 2019;78(6):736–745.
  4. 4. Chung SA, Langford CA, Maz M, et al. 2021 American College of Rheumatology/Vasculitis Foundation guideline for the management of antineutrophil cytoplasmic antibody-associated vasculitis. Arthritis Care Res. 2021;73(11):1583–1599.
  5. 5. Smolen JS, Landewé RBM, Bijlsma JWJ, et al. EULAR recommendations for the management of rheumatoid arthritis with synthetic and biological disease-modifying antirheumatic drugs: 2022 update. Ann Rheum Dis. 2023;82(1):3–18.
  6. 6. Australian Technical Advisory Group on Immunisation (ATAGI). Australian Immunisation Handbook. Australian Government Department of Health; 2024. Available from: immunisationhandbook.health.gov.au.
  7. 7. Rheumatic Heart Disease Australia (RHDAustralia). The 2020 Australian guideline for prevention, diagnosis, and management of acute rheumatic fever and rheumatic heart disease. 3rd ed. Darwin: Menzies School of Health Research; 2020.
  8. 8. Pharmaceutical Benefits Scheme (PBS). PBS Schedule. Australian Government Department of Health. Available from: pbs.gov.au. Accessed 2024.
  9. 9. Agarwal S, Cunnington J, Nossent J. Autoimmune disease in Indigenous Australians: a systematic review. Int J Rheum Dis. 2021;24(12):1487–1498.
  10. 10. Pisetsky DS. Antinuclear antibody testing — misunderstood or misused? Clin Immunol. 2023;255:109717.
  11. 11. Bertsias GK, Tektonidou M, Amoura Z, et al. Joint European League Against Rheumatism and European Renal Association–European Dialysis and Transplant Association (EULAR/ERA-EDTA) recommendations for the management of adult and paediatric lupus nephritis. Ann Rheum Dis. 2012;71(11):1771–1782.
  12. 12. Ledingham J, Deighton C; British Society for Rheumatology Standards, Audit and Guidelines Working Group. Update on the British Society for Rheumatology guidelines for prescribing TNFα blockers in adults with rheumatoid arthritis. Rheumatology. 2005;44(2):155–158.
  13. 13. National Health and Medical Research Council (NHMRC). National statement on ethical conduct in human research. Canberra: NHMRC; 2023 (updated).
for PBS-listed medicines at participating pharmacies.
Cultural safety
Engagement with Aboriginal Community Controlled Health Organisations (ACCHOs) is essential. Cultural safety training for non-Indigenous clinicians, use of Aboriginal Health Workers and Liaison Officers, and incorporation of traditional healing practices alongside Western medicine improve treatment adherence and outcomes. Avoidance of eye contact, respect for gender-sensitive examination practices, and understanding of sorry business protocols are critical elements of culturally safe care.
Medication adherence
Complex DMARD regimens with frequent monitoring requirements present adherence challenges. Long-acting depot injections (e.g., methotrexate SC) may improve adherence compared to oral regimens. Community pharmacy partnerships through the Indigenous Pharmacy Programmes improve medication management.
Specific conditions
Rheumatic heart disease (RHD) requires secondary prophylaxis with benzathine penicillin G (BPG) 1.2 MU IM every 3–4 weeks for a minimum of 10 years or until age 21 (whichever is longer). RHD registers (e.g., NT RHD Register) facilitate recall and follow-up. The Australian RHD Endgame Strategy targets elimination by 2031.
Referral pathways
Referral through ACCHOs and Aboriginal Hospital Liaison Officers (AHLOs) improves engagement. The Specialist Outreach Assistance Programme provides funded specialist visits to remote communities. NT, WA, and QLD have specific rheumatology outreach programmes targeting Indigenous communities.

📚 References

  1. 1. Australian Institute of Health and Welfare (AIHW). Autoimmune disease in Australia. Cat. no. PHE 312. Canberra: AIHW; 2023.
  2. 2. Fraenkel L, Bathon JM, England BR, et al. 2021 American College of Rheumatology guideline for the treatment of rheumatoid arthritis. Arthritis Care Res. 2021;73(7):924–939.
  3. 3. Fanouriakis A, Kostopoulou M, Alber K, et al. 2019 update of the EULAR recommendations for the management of systemic lupus erythematosus. Ann Rheum Dis. 2019;78(6):736–745.
  4. 4. Chung SA, Langford CA, Maz M, et al. 2021 American College of Rheumatology/Vasculitis Foundation guideline for the management of antineutrophil cytoplasmic antibody-associated vasculitis. Arthritis Care Res. 2021;73(11):1583–1599.
  5. 5. Smolen JS, Landewé RBM, Bijlsma JWJ, et al. EULAR recommendations for the management of rheumatoid arthritis with synthetic and biological disease-modifying antirheumatic drugs: 2022 update. Ann Rheum Dis. 2023;82(1):3–18.
  6. 6. Australian Technical Advisory Group on Immunisation (ATAGI). Australian Immunisation Handbook. Australian Government Department of Health; 2024. Available from: immunisationhandbook.health.gov.au.
  7. 7. Rheumatic Heart Disease Australia (RHDAustralia). The 2020 Australian guideline for prevention, diagnosis, and management of acute rheumatic fever and rheumatic heart disease. 3rd ed. Darwin: Menzies School of Health Research; 2020.
  8. 8. Pharmaceutical Benefits Scheme (PBS). PBS Schedule. Australian Government Department of Health. Available from: pbs.gov.au. Accessed 2024.
  9. 9. Agarwal S, Cunnington J, Nossent J. Autoimmune disease in Indigenous Australians: a systematic review. Int J Rheum Dis. 2021;24(12):1487–1498.
  10. 10. Pisetsky DS. Antinuclear antibody testing — misunderstood or misused? Clin Immunol. 2023;255:109717.
  11. 11. Bertsias GK, Tektonidou M, Amoura Z, et al. Joint European League Against Rheumatism and European Renal Association–European Dialysis and Transplant Association (EULAR/ERA-EDTA) recommendations for the management of adult and paediatric lupus nephritis. Ann Rheum Dis. 2012;71(11):1771–1782.
  12. 12. Ledingham J, Deighton C; British Society for Rheumatology Standards, Audit and Guidelines Working Group. Update on the British Society for Rheumatology guidelines for prescribing TNFα blockers in adults with rheumatoid arthritis. Rheumatology. 2005;44(2):155–158.
  13. 13. National Health and Medical Research Council (NHMRC). National statement on ethical conduct in human research. Canberra: NHMRC; 2023 (updated).