Generic
Promethazine Hydrochloride
30 brands available in the market
At a glance
Promethazine Hydrochloride is a phenothiazine derivative with antihistamine, anti-emetic, and sedative properties. It is used for allergic conditions of the respiratory tract and skin, sensitization reactions to drugs or foreign proteins, anaphylactic reactions, allergic rhinitis, urticaria, insomnia, and as a pre-operative sedative in surgery and obstetrics.
Description
Promethazine is a phenothiazine derivative that blocks postsynaptic mesolimbic dopaminergic receptors. It exhibits strong α-adrenergic blocking effects and depresses hypothalamic and hypophyseal hormone release. It competes with histamine for H1-receptors; muscarinic blocking may be responsible for antiemetic activity. It also reduces stimuli to the brainstem reticular system.
Indications
- Allergic conditions of the respiratory tract and skin
- Sensitization reactions to drugs or foreign proteins
- Anaphylactic reactions
- Allergic rhinitis
- Urticaria
- Insomnia (short-term)
- Pre-operative sedation in surgery and obstetrics
- Pediatric sedative
Therapeutic class
Anti-emetic drugs, Miscellaneous sedatives & hypnotics, Sedating Anti-histamine
Pharmacological class
Phenothiazine (H1 Antagonist)
Pharmacology
Promethazine blocks postsynaptic mesolimbic dopaminergic receptors and exhibits strong α-adrenergic blocking effects. It competes with histamine for H1-receptors for antihistamine effects. Muscarinic receptor blocking is responsible for antiemetic activity.
Mechanism of action
Relieves allergies, nausea, and provides sedation by blocking histamine effects.
Dosage
Adult Dose (Oral):
- Allergic conditions: 25 mg at night; may increase to 25 mg twice daily if needed; or 10-20 mg 2-3 times daily
- Motion sickness prophylaxis: 20-25 mg the night before travel; repeat the following morning if needed
- Insomnia (short-term): 20-50 mg at night
Pediatric Dose (Oral):
- Allergy (2-5 years): 5-15 mg/day; (5-10 years): 10-25 mg/day in 1-2 divided doses
- Motion sickness (2-5 years): 5 mg; (5-10 years): 10 mg
- Sedative (2-5 years): 15-20 mg; (5-10 years): 20-25 mg (single night-time dose)
Parenteral Dose:
- Adult: 25-50 mg deep IM or slow IV (max 100 mg)
- Child (5-10 years): 6.25-12.5 mg deep IM
Administration
- May be taken with or without food; take at a fixed time
- Swallow tablet whole; do not chew, crush, or break
Missed dose
If you miss a dose, take it as soon as you remember; skip if it's almost time for next dose; do not double the dose.
Side effects
Side Effects:
- Dry mouth
- Blurred vision
- Headache
- Dizziness
- Drowsiness
- Extrapyramidal effects (muscle spasms, tic-like movements)
- Neuroleptic malignant syndrome
- Allergic reactions
- Photosensitivity
- Urinary retention
Precautions & warnings
- May affect driving ability; do not drive if drowsy or dizzy
- Avoid alcohol (excessive drowsiness)
- May increase sensitivity to sunlight; use sunscreen
- Do not use for more than 7 days
- Discontinue 72 hours before allergy testing
Contraindications
- Coma or CNS depression of any cause
- Children under 2 years
- SC and intra-arterial administration
- Concurrent use or within 14 days of MAOI use
Drug interactions
- Aminoglycoside antibiotics: Masks ototoxicity
- Alcohol, hypnotics, barbiturates, opioids: Enhanced sedative effects
- Drugs that prolong QT interval: Ventricular arrhythmias
- Potentially fatal: Increased risk of extrapyramidal effects with MAOIs
Food interactions
Alcohol with Promethazine Hydrochloride may cause excessive drowsiness.
Use in pregnancy
Use in Pregnancy: May be unsafe during pregnancy; animal studies have shown harmful effects; use only if clearly needed.
Pregnancy Category: C — always consult a doctor before taking during pregnancy.
Use in lactation
Use in Lactation: Probably safe; limited human data suggests no significant risk; observe baby for excessive sleepiness with prolonged or repeated doses.
Pediatric use
Do not use in children under 2 years; do not give to neonates or premature infants.
Geriatric use
Elderly are particularly susceptible to anticholinergic effects and confusion; caution required.
Renal / hepatic impairment
Renal Impairment: Safe in kidney disease; dose adjustment may not be needed; severe kidney disease may cause excessive sleepiness; consult your doctor.
Hepatic Impairment: Caution in liver disease; dose adjustment may be needed; consult your doctor.
Overdose effects
Overdose: Children: excitation, ataxia, athetosis, hallucinations; Adults: drowsiness, coma; convulsions may occur; treatment: ipecacuanha or gastric lavage, supportive care, diazepam for convulsions.
Storage conditions
Protect from light; do not use after expiry date; keep out of reach of children.
Chemical structure
Promethazine Hydrochloride