Ondem
Ondem (Ondansetron 4 mg / 8 mg tablet) — selective 5-HT3 antagonist for chemo, radiation, post-operative, and severe gastroenteritis nausea. Alkem generic of Zofran.
✓ Medisch beoordeeld door Morgan Ellis — Apotheekonderzoeker · 8 jaar ervaring · Laatst beoordeeld: mei 2026
⚡ Quick Answer — What is Ondem?
Ondem is een film-coated tablet of ondansetron 4 mg / 8 mg, a selective serotonin 5-HT3 receptor antagonist. It is the most-used antiemetic worldwide and works against the strong serotonergic emetic stimulus generated by chemotherapy, radiation, surgery, gastroenteritis, and migraine. Manufactured by Alkem under WHO-GMP standards. Onset within 30 minutes orally and 8–12 hour duration; usually given 30–60 minutes before chemo or as needed for breakthrough nausea.
📦 Elke bestelling is gedekt door onze Reshipment Assurance Policy — als uw pakket niet binnen 20 werkdagen arriveert, sturen wij het opnieuw.
Waarom bestellen bij MedsBase
Onze generieke medicijnen zijn afkomstig van WHO-GMP gecertificeerde fabrikanten en worden wereldwijd verzonden in discrete, eenvoudige verpakkingen — geen medicijnnaam op de buitenkant van het pakket. Betalingen met kaart worden verwerkt via een gereguleerde processor (betalingsoverzichten vermelden een gereguleerde kaartbetalingprocessor — nooit “MedsBase” of een medicijnnaam). Crypto en SEPA bankoverschrijvingen worden ook geaccepteerd. Elke bestelling wordt ondersteund door ons Reshipment Assurance Policy.
When ondansetron is the right antiemetic
Ondansetron is the first-line antiemetic for serotonin-driven nausea — chemotherapy-induced nausea and vomiting (CINV), post-operative nausea and vomiting (PONV), radiation-induced nausea, and severe gastroenteritis. It is less useful for motion sickness and vestibular nausea (where the dominant pathway is histaminergic and cholinergic — promethazine/Avomine, cinnarizine, and meclozine work better) and not first-line for nausea-vomiting of pregnancy (NVP first-line is doxylamine + B6; ondansetron is reserved for refractory hyperemesis gravidarum after considering a small first-trimester cardiac/cleft-palate signal in observational studies).
Waarom bestellen bij MedsBase
Ondem is supplied from a WHO-GMP gecertificeerde fabrikant. Every order ships discreetly worldwide and is covered by our Reshipment Assurance Policy — if it does not arrive within 20 business days, we reship at no cost. Ondansetron is the global standard for serotonin-driven emesis with millions of doses delivered safely each year. Film-coated tablet formulation is convenient when active vomiting prevents reliable swallowing.
Werkingsmechanisme
Chemotherapy, radiation, and surgery damage gut enterochromaffin cells, which release massive amounts of serotonin (5-HT). The serotonin binds 5-HT3 receptors on vagal afferents and on the chemoreceptor trigger zone (area postrema), which signal the medullary vomiting centre. Ondansetron is a highly selective antagonist at the 5-HT3 receptor — it blocks this signal at both peripheral and central sites without affecting D2, H1, muscarinic, or alpha-adrenergic receptors. That selectivity explains its clean side-effect profile: minimal sedation, no extrapyramidal reactions, no anticholinergic burden.
Indicaties
- CINV: moderately or highly emetogenic chemotherapy (cisplatin, anthracyclines, cyclophosphamide regimens) — usually with dexamethasone ± aprepitant for highly emetogenic regimens.
- Radiation-induced nausea: total body irradiation, high-dose abdominal radiation.
- Post-operative nausea and vomiting (PONV): single 4 mg dose at induction or end of surgery.
- Severe gastroenteritis: dehydration risk in children/adults.
- Migraine-associated nausea: often with sumatriptan or other triptans.
- Refractory hyperemesis gravidarum: after first-line doxylamine+B6 (Doxinate, Pregnidoxin NU) and metoclopramide have failed; specialist supervision recommended.
Dosering
| Indicatie | Dosering |
|---|---|
| CINV (adult) | 8 mg 30 min before chemo, then 8 mg every 8–12 h for up to 5 days |
| PONV (adult) | 4 mg single dose, IV at induction or oral 1 h pre-op |
| Severe gastroenteritis (adult) | 4–8 mg every 8 h as needed (max 24 mg/day) |
| Paediatric (4–11 y, gastro) | 4 mg every 8 h (8–15 kg: 2 mg; 15–30 kg: 4 mg; >30 kg: 4–8 mg) |
| Ernstige leverfunctiestoornis | Maximum 8 mg/day (Child-Pugh C) |
| Single-dose maximum | 16 mg IV; 24 mg oral — do not exceed |
Swallow whole with water. Onset 30–60 minutes; if vomiting prevents oral intake, an ODT (e.g. Ondem MD, Emeset 4 ODT) or injection (Ondem Injection) is more reliable.
Bijwerkingen
- Common (> 10%): headache, constipation (the most clinically meaningful side effect — pre-empt with hydration and stool softener if multi-day course)
- Common (1–10%): mild flushing, fatigue, transient AST/ALT rise, dizziness, hot flushes after IV
- Minder vaak: bradycardia, hypotension, myalgia
- Zeldzaam maar ernstig: QT prolongation/torsades, serotonin syndrome (with SSRIs/SNRIs/triptans/MAOIs), severe hypersensitivity, transient blindness (very rare, with rapid IV)
- Minder vaak voorkomend: extrapyramidal reactions (rare with ondansetron unlike older antiemetics)
Geneesmiddelinteracties
- Apomorphine: ABSOLUTE contraindication — severe hypotension and loss of consciousness reported.
- Andere QT-verlengende geneesmiddelen (azithromycin, clarithromycin, citalopram, escitalopram, methadone, amiodarone, sotalol, fluoroquinolones, hydroxychloroquine, antipsychotics): avoid combination or monitor ECG.
- Serotonergic drugs (SSRIs, SNRIs, MAOIs, triptans, tramadol, fentanyl, linezolid, methylene blue): rare serotonin syndrome reported — counsel patients to recognise tremor/agitation/clonus/hyperthermia.
- Tramadol: ondansetron may reduce tramadol analgesic effect (5-HT3 blockade interferes with descending pain inhibition).
- Sterke CYP3A4-induceerders (rifampicin, phenytoin, carbamazepine): can lower ondansetron levels and reduce efficacy.
Veelgestelde vragen
How quickly does Ondem work?
Onset is 30–60 minutes. If you vomit within 30 minutes of swallowing the tablet, do not redose — switch to an ODT or injection if available.
Is Ondem safe in pregnancy?
Ondansetron is reserved for refractory hyperemesis gravidarum after doxylamine+B6 (Doxinate, Pregnidoxin NU), pyridoxine, and metoclopramide have failed. Some observational studies suggest a small first-trimester cardiac and cleft-palate signal; use should be discussed with a clinician.
Can I take Ondem for motion sickness?
Ondansetron works on the serotonin pathway and is not effective for motion sickness, which is histaminergic/cholinergic. Use promethazine (Avomine), cinnarizine, meclozine, or a hyoscine patch instead.
How is Ondem different from metoclopramide or domperidone?
Metoclopramide and domperidone are D2 antagonists — they speed gastric emptying and treat dyspepsia/regurgitation/gastroparesis nausea. Ondansetron is a 5-HT3 antagonist — better for chemo, radiation, surgery, severe gastroenteritis, and migraine nausea. Ondansetron is more expensive but cleaner (no extrapyramidal reactions, no hyperprolactinaemia).
Does Ondem cause drowsiness?
No. Unlike promethazine, prochlorperazine, and metoclopramide, ondansetron does not cause sedation or confusion and is preferred for ambulatory or driving patients.
What is the maximum dose?
Maximum single oral dose is 24 mg; maximum single IV dose is 16 mg (FDA cap). Total daily dose typically 24 mg/day; in severe hepatic impairment cap at 8 mg/day.
Can I take it with my SSRI antidepressant?
Short-term combinations are usually safe but counsel patients to recognise serotonin syndrome (tremor, agitation, hyperreflexia, clonus, fever). Long-term concurrent use is generally avoided when an alternative antiemetic is available.
Is constipation a problem?
Yes — ondansetron causes constipation in up to 1 in 10 users (more on multi-day chemo courses). Maintain hydration, fibre, and a stimulant laxative (senna/bisacodyl) prophylactically during chemo cycles.
Can Ondem be used in children?
Yes — weight-based dosing is well established for paediatric gastroenteritis (8–15 kg = 2 mg, 15–30 kg = 4 mg, >30 kg = 4–8 mg every 8 h). For active vomiting, an ODT or injection is more reliable than a tablet.
How is Ondem stored?
Store at room temperature (below 30°C), protect from light and moisture, keep out of reach of children. Tablets should remain in the original blister.
Other Nausea Treatments
- Ondem Injection (ondansetron 2 mg/ml IV/IM)
- Granicip (granisetron — longer-acting 5-HT3)
- Dompewal (domperidone — D2 antagonist for regurgitation)
- Stemetil MD (prochlorperazine ODT — vestibular nausea)
- Avomine (promethazine — motion sickness)
- Browse all Nausea Treatments
More options in Nausea Treatment
Gerangschikt op recente bestelvolumes van MedsBase — wat andere klanten in deze categorie kiezen.
| Sterkte | 8 mg |
|---|---|
| Hoeveelheid | 30 Tabletten, 60 Tabletten, 90 Tabletten, 180 Tabletten |
Ondem
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