Ondansteron

General

• Type: antiemetics
• Dosage Forms: 4mg, 8mg
• Common Trade Names: Zofran

Adult Dosing

• Nausea/Vomiting: 4-8mg q4h, max 24mg a day

Pediatric Dosing

• Nausea/Vomiting: 0.1mg/kg IV q4h max dose at once:4-8mg, max 24mg
• Gastroenteritis - Vomiting
  • 8 to 15 kg:
    • 2mg orally disintegrating tablet dissolved orally as a single dose
  • 15 to 30 kg:
    • 4mg orally disintegrating tablet dissolved orally as a single dose
  • Greater than 30 kg:
    • 8mg orally disintegrating tablet dissolved orally as a single dose

Special Populations

• Pregnancy Rating: B
  • Consider avoiding in 1st trimester; conflicting data regarding possible risk of teratogenicity
  • Newer data argues that ondansetron is not the cause of birth defects
• Lactation:safety unknown
• Renal Dosing:
  • Adult: not defined
  • Pediatric: not defined
• Hepatic Dosing: not defined
  • Adult: not defined
  • Pediatric: not defined

Contraindications

• Allergy to class/drug
• Congenital long QT syndrome
• Serotonin syndrome

Adverse Reactions

Serious

• bronchospasm
• steven-johnson syndrome
• QT prolongation
• torsades de pointes
• serotonin syndrome
• extrapyramidal symptoms
• blindness, transient

Common

• headache
• constipation
• fatigue
• hypoxia
• fever
• urinary retention
• agitation

Pharmacology

• Half-life: 4.6-5.7 hour
• Metabolism: liver
• Excretion: urine
• Mechanism of Action:selectively antagonizes serotonin 5-HT3 receptors