Indications of Promethazine Hydrochloride:

• Potent, long-acting antihistamine with additional antiemetic and sedative/calming effects.
• Symptomatic treatment of allergic conditions affecting the respiratory tract and skin.
• Management of drug or foreign protein sensitization and anaphylactic reactions.
• Relief of allergic rhinitis, urticaria, and insomnia.
• Sedation as an adjunct in pre-operative procedures in surgery and obstetrics.
• Pediatric sedation for children when clinically indicated.

Promethazine is a derivative of phenothiazine that works by blocking postsynaptic mesolimbic dopaminergic receptors in the brain. It has a strong α-adrenergic blocking effect and suppresses the release of hypothalamic and pituitary hormones. Additionally, it competes with histamine at H1 receptors, while its antimuscarinic action contributes to its antiemetic effects. Promethazine also reduces stimulation of the brainstem reticular system.

Promethazine is well absorbed from the gastrointestinal tract. Its clinical effects typically begin within about 20 minutes after oral administration and usually last for 4 to 6 hours, although effects may persist for up to 12 hours. The drug is metabolized in the liver into various compounds, with promethazine sulfoxides and N-demethylpromethazine being the main metabolites excreted in the urine.

Oral doseAdults:

Initial dose one 25 mg tablet at night; may be increased to two or three 25 mg tablets at night if necessary. In allergic conditions more frequently administration, twice or three times daily, may be necessary, starting with one or two 10 mg tablets and increasing as required.

Elderly: No specific dosage recommendations.

Children: They may be treated more conveniently by the elixir containing 5 mg/5 ml.

As an antihistamine in allergy:

• Children of 2-5 years: 5-15 mg
• Children of 5-10 years: 10-25 mg
• In the case where two doses in 24 hours are required, the lower dose stated should be given.
• As a sedative:
• Children of 2-5 years: 15-20 mg
• Children of 5-10 years: 20-25 mg
• Given as a single night-time dose

Parenteral doseAdult:

• 25-50 mg by deep intramuscular injection or, in emergency, by slow intravenous injection after dilution
• of the 2.5% solution to 10 times its volume with water for injection. The maximum parenteral dose is 100 mg.
• Children: 5-10 years: 6.25 to 12.5 mg by deep I.M. Injection

• Promethazine Hydrochloride can increase the effects of anticholinergic agents, tricyclic antidepressants, sedatives, or hypnotics. Therefore, alcohol should be avoided during treatment.
• Promethazine may interfere with immunologic urine pregnancy tests, potentially causing false-positive or false-negative results.
• Before performing skin allergy tests with allergen extracts, Promethazine should be stopped at least 72 hours prior, as it can suppress the skin’s histamine response, leading to false-negative results.

• Age restriction: Not to be used in children under 2 years of age.
• Allergy: Hypersensitivity to promethazine or any of its excipients.
• CNS depression: Should not be used in patients in a coma or with central nervous system depression of any cause.
• Neonates and premature infants: Promethazine must not be given to these patients.
• MAO inhibitors: Avoid use in patients who have taken monoamine oxidase inhibitors (MAOIs) within the past 14 days. 

• Nervous system disorders: Frequency Unknown: Neuroleptic Malignant Syndrome the elderly are particularly susceptible to the anticholinergic efects and confusion due to Promethazine, somnolence, dizziness, headaches, extrapyramidal efects including muscle spasm, tic-like movements of the head and face. A very serious and sometimes deadly health problem called neuroleptic malignant syndrome (NMS) may happen. Stop treatment and call your doctor right away if you have high fever, muscle cramps or stifness, dizziness, very bad headache, fast heartbeat, confusion, agitation, hallucinations, or are sweating a lot.
• Immune System Disorders- Frequency unknown: Allergic reactions, including urticaria, rash, pruritus, and anaphylaxis, have been reported.
• Skin and Subcutaneous Tissue Disorders- Frequency unknown: Photosensitivity reaction
• Metabolism and Nutrition Disorders- Frequency unknown: Anorexia
• Gastrointestinal Disorders- Frequency unknown: Epigastric discomfort, dry mouth
• Eye Disorders- Frequency unknown: Blurred vision
• Blood and Lymphatic System Disorders- Frequency unknown: Blood dyscrasias including hemolytic anemia, agranulocytosis
• Renal and Urinary Disorders- Frequency unknown: Urinary retention
• Psychiatric Disorders- Frequency unknown: Infants, newborns and premature are susceptible to the anticholinergic efects of promethazine, while other children may display paradoxical hyperexcitability, restlessness, nightmares, disorientation
• Cardiac Disorders- Frequency unknown: Palpitations, arrhythmias
• Vascular disorders- Frequency unknown: Hypotension
• Hepatobiliary disorders- Frequency unknown: Jaundice
• General Disorders and Administration Site Conditions- Frequency unknown: Tiredness

Use this drug only as recommended. Do not exceed the recommended dose. There have been case reports of promethazine abuse. Do not take for longer than 10 days.

Available epidemiological data and animal studies suggest that promethazine is generally safe during pregnancy; however, it should only be used if the physician determines it is essential. Its use is not recommended during the last two weeks before delivery due to the risk of irritability and excessive excitement in the newborn. High doses administered in late pregnancy have been associated with prolonged neurological disturbances in infants. Therefore, promethazine should be prescribed during pregnancy only when the expected benefits to the mother outweigh the potential risks to the fetus. Promethazine is also excreted in breast milk and may cause irritability and excitation in the nursing infant.

Precautions & Warnings for Promethazine:

• Reye’s Syndrome: Avoid use in children or adolescents showing signs or symptoms of Reye’s syndrome.
• Respiratory Conditions: Promethazine may thicken or dry lung secretions, making it harder to cough up mucus. Use caution in patients with asthma, bronchitis, or bronchiectasis.
• Cardiovascular Disease: Use carefully in patients with severe coronary artery disease.
• Eye Conditions: Use with caution in patients with narrow-angle glaucoma.
• Seizure Disorders: Use carefully in patients with epilepsy.
• Liver or Kidney Impairment: Use with caution in patients with hepatic or renal insufficiency.
• Urinary/ Digestive Tract Obstruction: Exercise caution in patients with bladder neck obstruction or pyloro-duodenal obstruction.

Symptoms of severe overdose vary widely. In children, they may present as a combination of excitation, ataxia, incoordination, athetosis, and hallucinations, whereas adults often experience drowsiness that may progress to coma. Convulsions can occur in both adults and children and may be preceded by either excitement or coma. Tachycardia may also develop, although cardiorespiratory depression is uncommon. If the patient is evaluated soon after ingestion, vomiting may be induced using ipecacuanha despite the antiemetic effect of promethazine; alternatively, gastric lavage can be performed. Management is primarily supportive, focusing on maintaining adequate respiratory and circulatory function. Convulsions should be treated with diazepam or another appropriate anticonvulsant.

Sedating Anti-histamine

• Protect from light and store in a safe place.
• Do not use after the expiration date.
• Keep all medicines out of reach of children.
• Use only with a prescription from a registered physician.