PHENERGAN

What it is

Phenergan contains promethazine hydrochloride and is available as a tablet and elixir formulation. The elixir contains promethazine hydrochloride 5 mg per 5 mL, while tablets contain either 10 mg or 25 mg of promethazine hydrochloride. Promethazine is a phenothiazine derivative that 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 acts as an antiemetic, hypnotic, tranquilliser, and a potentiator of anaesthetics, hypnotics, sedatives and analgesics.

Approved indications

— Treatment of allergic conditions including some allergic reactions to drugs, urticaria and allergic contact dermatitis, and allergic reactions to insect bites and stings. — Relief of excessive secretion in the upper respiratory tract as a result of hayfever and allergic rhinitis. — 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, not for more than 7 to 10 consecutive days. — Symptomatic management of measles and chicken pox. — Preanaesthetic medication for the prevention and control of postoperative vomiting.

Dosing overview

Phenergan must not be used in children under 6 years of age. This product is not suitable for children aged 6–12 years unless on pharmacist or medical advice. For tablets in allergic disorder, adults take 25 to 75 mg as a single dose at night, or 10 to 20 mg two to three times daily; children aged 6–12 years take 10 to 25 mg as a single dose at night, or 10 mg two to three times daily. For sedation, adults take 25 to 75 mg as a single dose at night and children aged 6–12 years take 10 to 25 mg as a single dose at night. For travel sickness, adults take 25 mg and children aged 6–12 years take 10 mg, to be taken the night before travel and repeated after 6 to 8 hours on the following day if required. For nausea and vomiting, adults take 25 mg every 4 to 6 hours to a maximum daily dose of 100 mg; children aged 6–12 years take 10 mg every 4 to 6 hours to a maximum daily dose of 25 mg. For the elixir in allergic disorder, children aged 6–12 years take 10 to 25 mL as a single dose at night, or 10 mL two to three times daily. For sedation with elixir, children aged 6–12 years take 10 to 25 mL as a single dose at night. For travel sickness with elixir, children aged 6–12 years take 10 mL to be taken the night before travel and repeated after 6–8 hours on the following day if required. For nausea and vomiting with elixir, children aged 6–12 years take 10 mL every 4 to 6 hours to a maximum daily dose of 25 mL.

Key safety warnings

Promethazine is contraindicated in children under 6 years of age because of the potential for fatal respiratory depression and psychiatric and central nervous system events; post-marketing cases of respiratory depression, including fatalities, have been reported with promethazine in paediatric patients less than 6 years of age. Caution should be exercised when administering promethazine to children 6 years of age or older because of the potential for fatal respiratory depression, including central and obstructive apnoea and reduced arousal; respiratory depression and apnoea, sometimes fatal, are associated with promethazine even if individualised weight-based dosing is used. QT interval prolongation has been reported with phenothiazines, and phenothiazine derivatives may potentiate QT interval prolongation which increases the risk of onset of serious ventricular arrhythmias of the torsade de pointes type, which is potentially fatal. Caution must be exercised when using promethazine due to the risk of sedation, and combined use with other sedative medicinal products is not recommended. Hypersensitivity reactions including anaphylaxis, urticaria and angioedema have been reported with promethazine use. Neuroleptic Malignant Syndrome, characterised by hyperthermia, extrapyramidal disorders, muscle rigidity, altered mental status, autonomic nervous instability and elevated CPK, may occur and is potentially fatal; promethazine must be discontinued immediately and intensive clinical monitoring and symptomatic treatment should be initiated. Solar dermatitis has been reported following oral doses of Phenergan in patients with eczema or a tendency to rheumatism; due to the risk of photosensitivity, exposure to the sun or ultraviolet light should be avoided during or shortly after treatment. Promethazine considerably affects the ability to drive a vehicle and operate machines; it may cause drowsiness, dizziness and blurred vision, drowsiness may continue the following day, and those affected should not drive or operate machinery.

Contraindications

Promethazine is contraindicated in patients with a history of hypersensitivity to the drug substance, substances of similar chemical structure, other phenothiazines or hypersensitivity to the other ingredients in the formulation. Phenergan sugar-free elixir should not be given to patients with allergies to sodium metabisulfite, sodium sulfite or sodium benzoate. Promethazine is contraindicated in children under 6 years of age because of the potential for fatal respiratory depression, psychiatric and central nervous system events. Promethazine is contraindicated in lactating women, patients taking monoamine oxidase inhibitors up to 14 days previously, patients with jaundice induced by other phenothiazine derivatives, and patients in coma or suffering from central nervous system depression of any cause or who have received high doses of other central nervous system depressants.

Regulatory history

Phenergan Elixir was first listed on the ARTG on 24 October 1997. The 10 mg and 25 mg tablet formulations were subsequently listed on 17 September 2001.