II. Indications
- Chemotherapy associated Nausea
- Radiation Therapy associated Nausea
- Vomiting refractory to first-line Antiemetics
-
Theophylline
Overdose
- Used instead of Phenothiazines due to Seizure risk
III. Mechanism
- Blocks peripheral and central 5HT3 receptors
- Peripheral 5HT3 receptors at vagal nerve terminals
- Central 5HT3 receptors at ChemoreceptorTrigger Zone in Medulla (area postrema controls Vomiting)
IV. Contraindications
- First trimester pregnancy (relative contraindication based on preliminary data)
- Previously thought to be safe in pregnancy
- FDA cautions use in Gestational age <10 weeks
- As of 2013, Ondansetron may be associated with 2 fold increased risk of congenital malformations
- References
V. Adverse Effects
- Mild Headache
- Dizziness
- Malaise or Fatigue
- Constipation
-
QT Prolongation
- More common with single doses >16 mg IV
- If QTc is already prolonged, Metoclopramide (Reglan) is a safe alternative without risk of QTc Prolongation
- Unlikely to cause harm (even at highest dose, Ondansetron prolongs QTc only 20 ms)
- Serotonin Syndrome
VI. Dosing: Ondansetron (Zofran)
-
Gastroenteritis using Ondansetron 4 mg ODT tabs
- Weight 8-15 kg: Ondansetron 2mg (half tab)
- Weight 15-30 kg: Ondansetron 4 mg (one tab)
- Weight >30 kg: Ondansetron 8 mg (two tabs)
- Freedman (2006) N Engl J Med 354:1698-705 [PubMed]
-
Nausea with Chemotherapy
- Intravenous dosing
- Timing
- First dose: 30 minutes before Chemotherapy
- Subsequent dosing: 4 and 8 hours after first dose
- Adult: 32 mg IV over 15 min
- Child: 0.15 mg/kg IV over 15 min (maximum: 8 mg/dose)
- Timing
- Oral dosing (ODT)
- Over age 12 years: 8 mg orally twice daily
- Age 4 to 11 years: 4 mg orally three times daily
- Age under 4 years: 0.15 mg/kg/dose (up to 4 mg)
- Intravenous dosing
-
Nausea with Radiation Therapy (adult)
- Dose: 8 mg orally four times daily
- Surgery related Nausea (adult)
- Prevention: 8-16 mg orally 1 hour before surgery
- Treatment: 4 mg IV or IM over 2-5 minutes
- Efficacy
- Meta-analysis of 7 randomized trials, n=1043
- Works in only 25% of patients
- No more effective than less expensive drugs
- Tramer (1997) BMJ 314:1088-93 [PubMed]
VII. Dosing: Dolasetron (Anzemet)
-
Nausea with Chemotherapy
- Dose: 1.8 mg/kg IV or PO for single dose to 100 mg
- Prevention of Surgery related Nausea
- Adult: 100 mg PO 2 hours before surgery
- Child: 1.2 mg/kg PO 2 hours before surgery
- Surgery related Nausea
- Adult: 12.5 mg IV for single dose
- Child: 0.35 mg/kg IV for single dose
VIII. Dosing: Granisetron (Kytril)
-
Nausea with Chemotherapy (administer 30 minutes before)
- Intravenous: 10 ug/kg IV over 5 minutes
- Oral: 1 mg PO bid for 1 day
-
Nausea with Radiation Therapy (adult)
- Dose: 2 mg PO 1 hour before each irradiation
IX. Preparations: Palonosetron (Aloxi)
- Indications: Preventing Chemotherapy indiuced Nausea
- Dosing: 0.25 mg IV 30 minutes before Chemotherapy
- Do not repeat dose more than once weekly
X. References
- Johnson (1993) Harriet Lane, Mosby, p. 521
- (2002) Tarascon Pocket Pharmacopoeia, p. 67
- (1998) Med Lett Drugs Ther 40(1026): 53-4 [PubMed]
- (1991) Med Lett Drugs Ther 33(847): 63-4 [PubMed]
- Bell and Lovecchio (2016) Crit Dec Emerg Med 30(8): 28
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ondansetron (on 12/21/2022 at Medicaid.Gov Survey of pharmacy drug pricing) | ||
ONDANSETRON 4 MG/5 ML SOLUTION | Generic | $0.25 per ml |
ONDANSETRON HCL 4 MG TABLET | Generic | $0.07 each |
ONDANSETRON HCL 4 MG/2 ML VIAL | Generic | $0.18 per ml |
ONDANSETRON HCL 8 MG TABLET | Generic | $0.10 each |
ONDANSETRON ODT 4 MG TABLET | Generic | $0.18 each |
ONDANSETRON ODT 8 MG TABLET | Generic | $0.20 each |