Promethazine (Phenergan)

Question 1

Drug Classficiation

Answer 1

Antiemetic/Anticholinergic

Question 2

Mechanism of Action

Answer 2

H1 (Histamine) and Muscarinic ACh antagonist ->inhibits communication from the chemoreceptor trigger zone (which recognizes emetic toxins) to the vomiting centers of the brain

Question 3

Pharmacokinetics

Answer 3

• Onset of Action- 5 minutes IV, 20 minutes IM
• Peak Effects- varies
• Duration of Effects- 4-6 hours
• Half-Life- 10-14 hours

Question 4

Indications/Field Use

Answer 4

Nausea/vomiting

Question 5

Contraindications

Answer 5

Hypersensitivity

Question 6

Side Effects/Adverse Reactions

Answer 6

Dizziness, drowsiness, sedation, blurred vision, bradycardia/tachycardia

Question 7

Dose

Answer 7

Adult:
12.5-25mg IV/IM
Pedi:
0.5mg/kg

Question 8

Precautions

Answer 8

May cause CNS depression or dystonia

Question 9

Drug-Drug Interactions

Answer 9

• Potentiates CNS depressant effect of narcotics, sedatives/hypnotics and alcohol
• Increased incidence of dystonia with concurrent use of MAOI