What is the use of Promethazine (Phenergan)?

From the Guidelines

Promethazine is primarily used as an antihistamine, sedative, anti-emetic, and anticholinergic agent, with a typical adult dose ranging from 12.5 to 25 mg intravenously, infused slowly to minimize the risk of hypotension, as an adjuvant for sedation during minor surgical and endoscopic procedures 1. The medication has been investigated for its use in managing allergic reactions and anaphylaxis, as treatment of postoperative nausea and vomiting, and as an adjuvant for postoperative pain and sedation.

• Key effects of promethazine include: + Blocking postsynaptic dopaminergic receptors in the brain + Competitive histamine H-receptor antagonist + Strong adrenergic inhibitory effect
• The clinical effects of promethazine are evident within 5 minutes of intravenous administration, with a duration of action of 4 to 6 hours, and a plasma half-life of 9 to 16 hours 2.
• Common uses of promethazine include: + Sedation during minor surgical and endoscopic procedures + Management of allergic reactions and anaphylaxis + Treatment of postoperative nausea and vomiting + Adjuvant for postoperative pain and sedation
• It is essential to use promethazine with caution in elderly patients and those with respiratory conditions, as it can suppress respiratory drive, and it should not be used in children under 2 years due to the risk of respiratory depression.
• Promethazine can interact with other central nervous system depressants, potentially causing dangerous levels of sedation, and its use may require a reduction in the dosage of standard sedation agents 1.

From the FDA Drug Label

Promethazine hydrochloride tablets are useful for: Perennial and seasonal allergic rhinitis. Vasomotor rhinitis. Allergic conjunctivitis due to inhalant allergens and foods. Mild, uncomplicated allergic skin manifestations of urticaria and angioedema. Amelioration of allergic reactions to blood or plasma. Dermographism Anaphylactic reactions, as adjunctive therapy to epinephrine and other standard measures, after the acute manifestations have been controlled. Preoperative, postoperative, or obstetric sedation. Prevention and control of nausea and vomiting associated with certain types of anesthesia and surgery. Therapy adjunctive to meperidine or other analgesics for control of post-operative pain Sedation in both children and adults, as well as relief of apprehension and production of light sleep from which the patient can be easily aroused. Active and prophylactic treatment of motion sickness. Antiemetic therapy in postoperative patients.

The use of Promethazine (Phenergan) includes:

• Allergic reactions: treatment of perennial and seasonal allergic rhinitis, vasomotor rhinitis, allergic conjunctivitis, and mild, uncomplicated allergic skin manifestations
• Sedation: preoperative, postoperative, or obstetric sedation, and sedation in both children and adults
• Pain management: therapy adjunctive to meperidine or other analgesics for control of post-operative pain
• Nausea and vomiting: prevention and control of nausea and vomiting associated with certain types of anesthesia and surgery, and antiemetic therapy in postoperative patients
• Motion sickness: active and prophylactic treatment 3

From the Research

Uses of Promethazine

• Promethazine is used as a treatment option for various indications, including nausea and vomiting, which is a common reason for emergency department visits 4.
• It is utilized for its antihistaminic, sedative, anti-kinetotic, antiemetic, and antimuscarinic effects 4.
• Promethazine is used for the management of allergic conditions, motion sickness, and nausea, as well as a sedative to treat psychiatric disorders 5.
• It is also used to treat acute agitation in psychiatric patients, often in combination with other psychotropic drugs such as haloperidol 6.

Administration and Precautions

• Injectable promethazine should be used with caution to minimize the risk of serious patient harm in the event of intra-arterial or perivascular extravasation when given parenterally 4.
• Patient safety organizations have called for hospitals to remove injectable promethazine from formularies due to the risk of rare but serious limb-threatening adverse effects 4.
• The U.S. Food and Drug Administration has added dilution and administration recommendations for intravenous administration and stated a preference for intramuscular administration 4.
• When prescribing promethazine, its pharmacological properties and risks of severe intoxication in case of overdose should be considered, and the lowest possible amount should be prescribed 7.

Potential Risks and Side Effects

• Promethazine has been associated with rare but serious limb-threatening adverse effects after extravasation or inadvertent intra-arterial injection 4.
• It has also been linked to neuroleptic malignant syndrome, a life-threatening condition characterized by hyperthermia, muscle rigidity, and altered mental status 8.
• Overdoses with promethazine can lead to severe intoxication, and the substance has contributed to a number of poisoning deaths 7.