Ondansetron

Aliases: Zofran

Indications: Moderate to severe nausea, vomiting       

Contraindications: Known allergy, do not use Zofran concurrently with Procainamide, Haldol, or amiodarone due to QT prolongation. 

Concentrations: 

Injection: 2 mg/mL

Tablet: 4 mg

Dosing

Adult:

Indication Dose Route Note 
Moderate to Severe Nausea/Vomiting   4 mg PO/IV/IMRepeat every 15 minutes PRN  

Pediatric:

Indication Dose Route Note 
Moderate to Severe Nausea/Vomiting  0.1 mg/kg
(Max: 4 mg)		PO/IV/IMIM preferred over IV
Moderate to Severe Nausea/Vomiting  4 mgPOFor 25 kg and up 
Use Handtevy or Approved Pediatric Reference Guide for Amount to Administer

Precautions: Caution use in patients with long QTc syndrome or on drugs that prolong the QTc.  

Adverse/Side Effects: Arrhythmias (including ventricular and supraventricular tachycardia, premature ventricular contractions, and atrial fibrillation), bradycardia, electrocardiographic alterations (including second-degree heart block, QT/QTc interval prolongation, and ST segment depression), palpitations, and syncope. 

Class: Anti-emetic, Selective Serotonin (5HT3) Receptor Antagonist  

Mechanism of Action: Ondansetron reduces the activity of the vagus nerve, which activates the vomiting center in the medulla oblongata and blocks serotonin receptors in the chemoreceptor trigger zone. It has little effect on vomiting caused by motion sickness. Safely tolerated at high dose ranges.

Onset of ActionPeak EffectDuration of Action 
< 30 minutes30-120 minutesVaries