Indications for Promethazine (Phenergan)
Promethazine is indicated for allergic conditions, nausea and vomiting, sedation, and as an adjunct to analgesics for pain management, with specific FDA-approved indications varying by administration route.
Primary Indications
Allergic Conditions
- Treatment of perennial and seasonal allergic rhinitis 1
- Management of vasomotor rhinitis 1
- Treatment of allergic conjunctivitis due to inhalant allergens and foods 1
- Management of mild, uncomplicated allergic skin manifestations including urticaria and angioedema 1
- Amelioration of allergic reactions to blood or plasma 2, 1
- Treatment of dermographism 1
- Adjunctive therapy to epinephrine in anaphylactic reactions, after acute manifestations have been controlled 2, 1
Nausea and Vomiting
- Prevention and control of nausea and vomiting associated with certain types of anesthesia and surgery 2, 1
- Active treatment and prophylaxis of motion sickness 2, 1
- Antiemetic therapy in postoperative patients 1
- Treatment of established postoperative nausea and vomiting, with lower doses (6.25mg) being as effective as higher doses while causing less sedation 3, 4
Sedation
- Preoperative, postoperative, or obstetric sedation (including during labor) 2, 1
- Relief of apprehension and production of light sleep from which the patient can be easily aroused 2, 1
- As an adjunct for sedation during minor surgical and endoscopic procedures 5
Pain Management
- Adjunctive therapy to analgesics (particularly meperidine) for control of post-operative pain 2, 1
- Used with reduced amounts of meperidine or other narcotic analgesics as an adjunct to anesthesia and analgesia 2
Pharmacology and Administration
Mechanism of Action
- Blocks postsynaptic dopaminergic receptors in the brain 5
- Has strong adrenergic inhibitory effects 5
- Acts as a competitive histamine H1-receptor antagonist, blocking most pharmacologic effects of histamine mediated at H1 receptors 5
- Possesses anticholinergic effects 5
Administration Details
- Intravenous dosing: 12.5-25 mg, infused slowly (25 mg/min) to minimize hypotension risk 5
- Total dose of 25-100 mg may be used as an adjuvant to narcotics and benzodiazepines 5
- Clinical effects are evident within 5 minutes of intravenous administration 5
- Duration of action is 4-6 hours with a plasma half-life of 9-16 hours 5
- Lower doses (6.25 mg) may be as effective as higher doses for nausea/vomiting with fewer adverse effects 3, 4
- FDA recommends preferential use of intramuscular route over intravenous administration due to safety concerns 6
Adverse Effects and Precautions
Common Adverse Effects
- Hypotension, particularly with rapid IV administration 5
- Sedation, which may be more pronounced than with other antiemetics 7
- Respiratory depression 5
- Dizziness, blurred vision, dry mouth 5
Serious Adverse Effects
- Neuroleptic malignant syndrome 5
- Extrapyramidal effects ranging from restlessness to oculogyric crises 5
- Risk of vascular damage upon intravenous administration 7
- Rare but serious limb-threatening adverse effects after extravasation or inadvertent intra-arterial injection 6
Special Populations
- Black box warning regarding fatal respiratory depression in children younger than 2 years 5
- In elderly patients, lower doses (6.25 mg) may be as effective as higher doses with fewer adverse drug reactions 4
- May require reduction in dosage of standard sedation agents when used as an adjunct 5
Clinical Considerations
- When used for endoscopic procedures, promethazine has been successfully administered in combination with meperidine 5
- For breakthrough treatment of chemotherapy-induced nausea/vomiting, promethazine 12.5-25 mg PO or IV (central line only) every 4 hours may be used 5
- For patients with opioid-induced pruritus, promethazine may be beneficial as an antihistamine option 5
- Due to safety concerns, some patient safety organizations have called for hospitals to remove injectable promethazine from formularies 6