Data Sheet

Phenergan^®

Promethazine hydrochloride tablets and elixir

Name of Medicine

Phenergan Tablets

Phenergan Elixir

Non-proprietary Name

Promethazine hydrochloride

Chemical Structure

Promethazine hydrochloride has the following structural formula:

Structural Formula of Phenergan

CAS Number

58-33-3

Description

Promethazine hydrochloride is a white or faintly yellow, practically odourless, crystalline powder. It is very soluble in water, freely soluble in alcohol and in chloroform, and practically insoluble in ether.

Phenergan Elixir contains promethazine hydrochloride 5 mg/5 mL. Phenergan Elixir also contains maltitol solution, acesulfame potassium, sodium benzoate, sodium citrate, citric acid, sodium sulfite, sodium metabisulfite, ascorbic acid, caramel and orange juice flavour.

Phenergan tablets contain 10 mg or 25 mg of promethazine hydrochloride. Phenergan Tablets also contain lactose, starch maize, povidone, magnesium stearate, hypromellose, macrogol 200 and blue opaspray.

Pharmacology

Promethazine, a phenothiazine derivative, is a long acting antihistamine with mild atropine-like anticholinergic effects and some antiserotonin effects, and because of its marked effect on the central nervous system (CNS), it acts as an antiemetic, hypnotic, tranquilliser, and a potentiator of anaesthetics, hypnotics, sedatives and analgesics.

Pharmacokinetics

Promethazine is well absorbed after oral administration. Peak plasma concentrations are reached 2 to 3 hours after administration by this route, although there is low systemic bioavailability after oral administration, due to high first-pass metabolism in the liver. Promethazine crosses the blood-brain barrier and the placenta, and is distributed into breast milk. It is highly bound to plasma proteins (76-93%). Promethazine undergoes extensive metabolism, predominantly to promethazine sulfoxide, and also to N-desmethylpromethazine. It is excreted slowly via the urine and bile, mainly as metabolites. Elimination half-lives of 5 to 14 hours have been reported. The antihistamine action has been reported to be between 4 and 12 hours.

Indications

Allergies: Treatment of allergic conditions including some allergic reactions to drugs, urticaria and allergic contact dermatitis, and allergic reactions to insect bites and stings.

Upper respiratory tract: Relief of excessive secretion in the upper respiratory tract as a result of hayfever and allergic rhinitis.

Nausea and vomiting: Antiemetic for vomiting from various causes, including postoperative vomiting, irradiation sickness, drug induced nausea and motion sickness.

Sedation: For short term use under the advice of a doctor or pharmacist. Do not use for more than 7 to 10 consecutive days.

Other: Promethazine has sedative effects and can be used in the symptomatic management of measles and chicken pox. Promethazine can be used as a preanaesthetic medication for the prevention and control of post operative vomiting.

Contraindications

Promethazine is contraindicated for use in patients with a history of hypersensitivity to the drug substance, substances of similar chemical structure or hypersensitivity to the other ingredients. Phenergan Elixir should not be given to patients with allergies to sodium metabisulfite, sodium sulfite or sodium benzoate.

Promethazine is contraindicated for use in:

newborns or premature infants
children under 2 years of age (see Precautions)
lactating women
patients taking monoamine oxidase inhibitors (MAOIs) (see Interactions with Other Medicines)
jaundice induced by other phenothiazine derivatives
patients who have received high doses of other CNS depressants and/or are comatose.

Refer to 'Interactions with Other Medicines' for additional information.

Precautions

Caution is advised in patients with:

cardiovascular disease
impaired hepatic function
renal failure or impairment
acute or chronic respiratory impairment
epilepsy
hypertensive crisis
narrow-angle glaucoma
stenosing peptic ulcer
symptomatic prostatic hypertrophy
bladder neck obstruction
pyloroduodenal obstruction

Promethazine may cause drowsiness and may increase the effects of alcohol. Drowsiness may continue the following day. Those affected should not drive or operate machinery; alcohol should be avoided.

QT interval prolongation has been reported with phenothiazines. Refer to 'Interactions with Other Medicines' for additional information.

Use in Pregnancy (Category C)

Promethazine, owing to its pharmacological effects, has caused or may be suspected of causing, harmful effects on the human foetus or neonate without causing malformations. These effects may be reversible. When promethazine has been given in high doses during late pregnancy, promethazine has caused prolonged neurological disturbances in the infant. Promethazine should be used in pregnancy only if the potential benefits to the patient are weighed against the possible risk to the foetus.

Use in Lactation

Promethazine is excreted in breast milk. Therefore it should not be used for breastfeeding women.

Paediatric Use

Children may experience paradoxical excitation with promethazine.

The use of promethazine should be avoided in children and adolescents with signs and symptoms suggestive of Reye's Syndrome.

This product should not be used in children under 2 years of age, due to the potential for fatal respiratory depression.

Caution should be exercised when administering promethazine to children as there is potential for central and obstructive apnoea and reduced arousal. Excessive dosages of antihistamines in children may cause hallucinations, convulsions and sudden death.

Use in the Elderly

The elderly may experience paradoxical excitation with promethazine. The elderly are more likely to have CNS depressive side effects, including confusion and are more susceptible to the antimuscarinic effects of antihistamines, including hypotension (see Contraindications).

Interactions with Other Medicines

Promethazine may cause drowsiness and may enhance the sedative effects of CNS depressants (including alcohol, barbiturates, hypnotics, opioid analgesics, anxiolytic sedatives and neuroleptics), and have additive antimuscarinic actions with other antimuscarinic drugs (atropine, tricyclic antidepressants). Interactions between promethazine and monoamine oxidase inhibitors and tricyclic antidepressants (TCAs) may prolong and intensify the anticholinergic and CNS depressive effects

Warnings

Hypertensive crisis: Promethazine should be used with caution, if at all, in these patients.

Solar dermatitis has been reported following oral doses of Phenergan in patients with eczema or a tendency to rheumatism.

Epilepsy: Epileptic patients may experience increased severity of convulsions.

Effects on Ability to Drive and Use Machinery

Ambulant patients receiving Phenergan for the first time should not be in control of vehicles or machinery for the first few days until it is established that they are not hypersensitive to the central nervous effects of the medicine and do not suffer from disorientation, confusion or dizziness.

Adverse Effects

CNS Effects

CNS depressive effects of promethazine include sedation and impaired performance (impaired driving performance, poor work performance, incoordination, reduced motor skills, and impaired information processing). Performance may be impaired in the absence of sedation and may persist the morning after a night-time dose.

The CNS stimulatory effects of promethazine may include anxiety, hallucinations, appetite stimulation, muscle dyskinesias and activation of epileptogenic foci.

High doses of promethazine may cause nervousness, tremor, insomnia, agitation, and irritability.

Anticholinergic Effects

Side effects of promethazine associated with cholinergic blockage include dryness of the eyes, mouth and nose, blurred vision, urinary hesitancy and retention, constipation and tachycardia.

More common reactions

Gastrointestinal: Dry mouth, epigastric distress, loss of appetite, nausea, vomiting, constipation, diarrhoea

Nervous system: Sedation, restlessness, dizziness, lassitude, incoordination, fatigue

Ocular: Blurred vision

Less common reactions

Cardiovascular: Tachycardia, bradycardia, faintness

Dermatological: Contact dermatitis (topical), photosensitization, urticaria, angioneurotic oedema, pruritus

Haematological: Leucopenia, agranulocytosis, aplastic anaemia, thrombocytopenic purpura.

Hepatic: Jaundice

Musculoskeletal: Extrapyramidal symptoms

Nervous-system: Tinnitus, euphoria, nervousness, insomnia, convulsive seizures, oculogyric crises, excitation, catatonic-like states, hysteria, extrapyramidal symptoms, tardive dyskinesia

Respiratory: Marked irregular respiration

Severe or life-threatening reactions

Agranulocytosis, anaphylaxis.

The preservatives used in Phenergan Elixir have been reported to cause hypersensitivity reactions (sodium metabisulphite, sodium sulphite, or sodium benzoate).

Dosage and Administration

This product should not be used in children under 2 years of age (see Precautions).

Dosage varies according to the condition being treated and the individual's response.

Allergic disorders

Children: 2 - 5 years: 5 to 15 mg (5 to 15 mL) as a single dose at night, or 5 mg two to three times daily.

Children: 6 - 12 years: 10 to 25 mg (10 to 25 mL) as a single dose at night, or 10 mg two to three times daily.

Adults: 25 to 75 mg as a single dose at night, or 10 to 20 mg two to three times daily.

Sedation

Children: 2 - 5 years: 5 to 15 mg (5 to 15 mL).

Children: 6 - 12 years: 10 to 25 mg (10 to 25 mL).

Adults: 25 to 75 mg as a single dose at night.

Given as a single dose at night.

Travel sickness

Children 2 - 5 years: 5 mg (5 mL).

Children: 6 - 12 years: 10 mg (10 mL).

Adults: 25 mg.

To be taken the night before travel and repeated after 6 to 8 hours on the following day if required.

Nausea and vomiting

Children: 2 - 5 years: 5 mg (or 5 mL) every 4 to 6 hours to a maximum daily dose of 15 mg (or 15 mL).

Children: 6 - 12 years: 10 mg (or 10 mL) every 4 to 6 hours to a maximum daily dose of 25 mg (or 25 mL).

Adults: 25 mg every 4 to 6 hours to a maximum daily dose of 100 mg.

Overdosage

The chief sign of acute poisoning from ingestion of an overdose of Phenergan is unconsciousness, which is commonly delayed. In addition, convulsions, hallucinations, delirium, acute anxiety, psychotic reactions, extreme hyperaesthesia and hyperalgesia with extensor plantar responses may occur. Anticholinergic action may cause tachycardia, flushed skin, dry mouth and sometimes mydriasis and urinary retention.

In adults, CNS depression is more common, with drowsiness, coma, convulsions, progressing to respiratory failure or cardiovascular collapse.

In infants and children, CNS stimulation predominates over CNS depression causing ataxia, excitement, tremors, psychoses, hallucinations, convulsions and possibly hyperpyrexia, which may be followed by deepening coma and cardiorespiratory collapse.

Treatment

Similar to that of other phenothiazines. Symptomatic supportive therapy is indicated and maintenance of adequate ventilation should be instituted if necessary.

In case of overdose, contact the Poisons Information Centre.

Presentation and Storage Conditions

Elixir

5 mg/5 mL. Sugar free, alcohol free, orange flavoured, 100 mL. Store below 25°C. Protect from light.

Tablets

10 mg: Circular, film-coated biconvex tablets with bevelled edges, pale blue in colour, one face impressed 'PN' above '10', the reverse face plain. Available in packs of 25 and 50.

Store below 30°C.

25 mg: Circular, film-coated biconvex tablets with bevelled edges, pale blue in colour, one face impressed 'PN' above '25', the reverse face plain. Available in packs of 25 and 50.