Promethazine Hydrochloride: Brands, Price & Uses in Bangladesh

Promethazine Hydrochloride is a first-generation phenothiazine antihistamine with antiemetic and sedative properties. It is FDA-approved and used for the following indications:

• Allergic conditions: Symptomatic treatment of allergic conditions such as perennial and seasonal allergic rhinitis, allergic conjunctivitis, urticaria, and angioedema; also used as adjunctive therapy in anaphylaxis after acute symptoms have been controlled.
• Nausea and vomiting: Prevention and control of nausea and vomiting associated with various conditions, including postoperative nausea and vomiting.
• Motion sickness: Prevention and treatment of motion sickness.
• Sedation: Preoperative, postoperative, and obstetric sedation; sedation and relief of apprehension in adults and pediatric patients (2 years and older), and to provide light sedation for surgical or diagnostic procedures.
• Adjunct to analgesics: Used with reduced doses of analgesics for control of postoperative pain, as it potentiates the effect of analgesics when used adjunctively.

In Bangladesh, Promethazine Hydrochloride is also commonly used off-label for short-term relief of cough associated with allergic conditions, as part of combination cough preparations, and as a nighttime sedative-antihistamine; such off-label use should be guided by a physician.

Dosage of Promethazine Hydrochloride must be individualized according to the indication, age, and response of the patient, using the lowest effective dose.

Allergy (Adults)

• 12.5 mg before meals and at bedtime, or 25 mg at bedtime if needed.

Allergy (Children 2 years and older)

• 6.25-12.5 mg three times daily, or 25 mg at bedtime, not to exceed the lowest effective dose.

Nausea and Vomiting (Adults)

• 12.5-25 mg every 4-6 hours as needed, oral, rectal, or by deep intramuscular injection.

Nausea and Vomiting (Children 2 years and older)

• 0.25-0.5 mg/kg (or approximately 12.5-25 mg) every 4-6 hours as needed; use lowest effective dose.

Sedation (Adults)

• 25-50 mg at bedtime.

Sedation (Children 2 years and older)

• 12.5-25 mg at bedtime.

Motion Sickness (Adults)

• 25 mg twice daily; first dose 30-60 minutes before travel, repeated in 8-12 hours if needed.

Injectable use

• For parenteral use, the deep intramuscular route is preferred. Injectable Promethazine Hydrochloride is not approved for subcutaneous administration due to risk of severe tissue injury, including gangrene. When given intravenously, it must be given as a slow injection into a running IV line, in the lowest possible concentration, due to risk of severe chemical irritation and tissue damage.

Promethazine Hydrochloride is contraindicated in children under 2 years of age due to the risk of fatal respiratory depression (see Contraindications). Use should not exceed 10 days for cough/cold symptoms without medical reassessment.

Common side effects of Promethazine Hydrochloride include:

• Drowsiness and sedation (very common, dose-related)
• Dizziness, confusion, disorientation (especially in elderly patients)
• Dry mouth, blurred vision, constipation, urinary retention (anticholinergic effects)
• Photosensitivity (increased sun sensitivity)

Serious but less common adverse effects include:

• Respiratory depression, which can be fatal, particularly in young children and in combination with other CNS depressants (boxed warning).
• Severe tissue injury, including gangrene, with inadvertent intra-arterial injection or perivascular extravasation of the injectable form (boxed warning).
• Neuroleptic malignant syndrome (rare): high fever, severe muscle rigidity, altered mental status, and autonomic instability - a medical emergency.
• Extrapyramidal symptoms (abnormal movements, muscle stiffness).
• Blood dyscrasias (leukopenia, agranulocytosis) - rare.
• Cardiac arrhythmias and QT prolongation - rare.
• Lowered seizure threshold in patients with seizure disorders.

Patients should seek prompt medical attention for difficulty breathing, unusual muscle stiffness, high fever, or signs of an allergic reaction while taking Promethazine Hydrochloride.