Antiemetics (4)

Question 1

Prochlorperazine

Answer 1

Brand Name: Compazine

Classification: Phenothiazine

Action: Suppresses the CTZ; has antihistaminic effects

Indications: Nausea, vomiting, anxiety, psychosis

Contraindications: Hypersensitivity, small children, or pregnancy

Dose: 5-10mg

Routes: IV, IM, IO, PO

Adverse: Drowsiness, dizziness, sedation, dry mouth, extrapyramidal symptoms

Other: Can potentiate CNS depressants (e.g. alcohol)

Question 2

Promethazine

Answer 2

Brand Name: Phenergan

Classification: Phenothiazine

Action: Suppresses the CTZ; has antihistaminic effects

Indications: Nausea, Vomiting

Contraindications: Hypersensitivity to the drug

Dose: 12.5-25 mg

Routes: IV, IM, PO

Adverse Effects: Drowsiness, Dizziness, Sedation, Dry Mouth, Extrapyramidal symptoms

Other: Can potentiate CNS depressants (e.g., alcohol), Extravasation can cause local tissue injury, rarely used

Question 3

Droperidol

Answer 3

Brand Name: Inapsine

Classification: Antidopaminergic

Action: Blocks dopamine receptors (D2)

Indications: Nausea, vomiting, psychosis

Contraindications: Hypersensitivity, prolonged QTc on ECG

Dose: 1.25-2.50mg

Routes: IV, IM

Adverse: QTc prolongation, hypotension, tachycardia

Other: Has “Black Box” warning due to possible QT prolongation

Question 4

Ondansetron

Answer 4

Brand Name: Zofran

Classification: Serotonin antagonist

Action: Selectively blocks 5-HT3 serotonin receptors, including those in the CTZ and vagus nerve terminals

Indications: Nausea and Vomiting

Contraindications: Hypersensitivity

Dose: 4-8 mg

Routes: IV, IM, PO, SL

Adverse Effects: Dizziness and Lightheaded

Other: Commonly used in emergency medicine because of good safety profile