Ondansetron CPG

Question 1

Ondansetron - Presentation

Answer 1

4 mg orally disolved tablet

8 mg in 4 mL glass bottle

Question 2

Ondansetron - Pharmacology

Answer 2

Anti-emetic

Action:

5HT₃ antagonist which blocks receptors both centrally and peripherally

Question 3

Ondansetron - Metabolism

Answer 3

By the liver

Question 4

Ondansetron - Primary emergency indications

Answer 4

1. Undifferentiated nausea and vomiting
2. Prophylaxis for spinally immobilised or eye injured Pt
3. Vestibular nausea in Pt <21 years of age

Question 5

Ondansetron - Contraindications

Answer 5

1. Known hypersensitivity
2. Concurrent Apomorphine use
3. Known long Q-T syndrome
4. Hypokalaemia or hypomagnesaemia

Question 6

Ondansetron - Precautions

Answer 6

1. Pt with liver disease should not receive more than 8 mg of Ondansetron per day
2. Care should be taken with patients on diuretics who may have an underlying electrolyte imbalance
3. Ondansetron contains aspartame and should not be given to patients with phenylketonuria
4. Concurrent use of Tramadol
5. Pregnancy

Question 7

Ondansetron - Route of administration

Answer 7

Oral (ODT)

IV

IM

Question 8

Ondansetron - Side effects

Answer 8

Rare (<0.1%)

Hypersensitivity reactions (including anaphylaxis)

Q-T prolongation

Widened QRS complex

Tachyarrythmias (including AF and SVT)

Seizures

Extrapyramidal reaction

Visual disturbances (including transient loss of vision)

Common (>1%)

Constipation

Headache

Fever

Dizziness

Rise in liver enzymes

Question 9

Ondansetron - Special notes

Answer 9

ODT

Onset: 2min

Peak: 20min

Duration: 120min

IV

Onset: 5min

Peak: 10min

Duration: between 2.5 and 6.1hrs

IV doses should be delivered as a slow push (minimum 30sec)