Promethazine is used to prevent and treat nausea and vomiting related to certain conditions (such as before/after surgery, motion sickness). It is also used to treat allergy symptoms such as rash, itching, and runny nose.
H1-Receptor Antagonist; Antiallergy
Promethazine is a phenothiazine derivative which blocks postsynaptic mesolimbic dopaminergic receptors in the brain. It exhibits strong α-adrenergic blocking effect and depresses the release of hypothalamic and hypophyseal hormones. It competes with histamine for the H1-receptor; muscarinic blocking effect may be responsible for antiemetic activity. It also reduces stimuli to the brainstem reticular system.
Promethazine is well absorbed from the gastrointestinal tract. Clinical effects are apparent within 20 minutes after oral administration and generally last four to six hours, although they may persist as long as 12 hours. Promethazine is metabolized by the liver to a variety of compounds; the sulfoxides of promethazine and N-demethylpromethazine are the predominant metabolites appearing in the urine.
ORAL Allergic conditions: Adult: As hydrochloride: 25 mg at night inresed to 25 mg bid, if needed; alternatively, 10-20 mg bid or tid.Child:As hydrochloride: 5-10 yr: 10-25 mg daily; 2-5 yr: 5-15 mg daily. Doses are given in 1 or 2 divided doses. PARENTERAL Allergic conditions: Adult: As hydrochloride: 25-50 mg, given via IM or slow IV inj or injected into the tubing of a freely running infusion at a conc of not >25 mg/mI & infused at a rate of not >25 mg/min. Max dose: 100 mg. Child:As hydrochloride: 5-10 yr: 6.25-1 2.5 mg by deep lM inj.
Promethazine Hydrochloride may enhance the action of any anticholinergic agent, tricyclic antidepressant, sedative or hypnotic, Alcohol should be avoided during drug treatment.
Phenergan may interfere with immunologic urine pregnancy tests to produce false-positive or false-negative results.
Phenergan should be discontinued at least 72 hours before the start of skin tests using allergen extracts as it may inhibit the cutaneous histamine response thus producing false-negative results.
Hypersensitivity, coma, porphyria, cardiac disease, hypokalaemia, intraarterial or SC inj, neonates & young children, pregnancy, lactation. Elderly, glaucoma, epilepsy, CVS disease, impaired liver function, asthma, urinary retention, prostatic hyperplasia, pyloroduodenal obstwction. May cause drowsiness. For parenteral admin: Drug must be administered carefully & slowly; incorrect admin can lead to severe tissue injury.
CNS depression, paradoxical excitation in childn, dryness of mouth, blurring of vision, retention of urine, constipation, glaucoma, tachycardia. headache, hypotension, tinnitus.
This drug should be used during pregnancy only if the benefit outweighs the risk to the fetus. Use is not recommended and a decision should be made to discontinue breastfeeding or discontinue the drug, taking into account the importance of the drug to the mother.
Symptoms of severe over dosage are variable. They are characterised in children by various combinations of excitation, ataxia, incoordination, athetosis and hallucinations, while adults may become drowsy and lapse into coma. Convulsions may occur in both adults and children; coma or excitement may precede their occurrence. Tachycardia may develop. Cardiorespiratory depression is uncommon. If the patient is seen soon enough after ingestion, it should be possible to induce vomiting with ipecacuanha despite the antiemetic efect of promethazine; alternatively, gastric lavage may be used. Treatment is otherwise supportive with attention to maintenance of adequate respiratory and circulatory status. Convulsions should be treated with diazepam or other suitable anticonvulsant.
Protect from light. Do not use later than the date of expiry. Keep all medicines out of the reach of children. To be dispensed only on the prescription of a registered physician
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