Piriton Allergy Tablets

Round, biconvex, yellow tablets engraved with a P to one side of the breakline. Each tablet contains 4 milligrams of chlorphenamine maleate.

Tablet.

Piriton Allergy Tablets are indicated for symptomatic control of all allergic conditions responsive to antihistamines, including hay fever, vasomotor rhinitis, urticaria, angioneurotic oedema, food allergy, drug and serum reactions, insect bites.

Also indicated for the symptomatic relief of itch associated with chickenpox.

Piriton Allergy Tablets are contra-indicated in patients who are hypersensitive to antihistamines or to any of the tablet ingredients.

The anticholinergic properties of chlorphenamine are intensified by monoamine oxidase inhibitors (MAOIs). Piriton Allergy Tablets is therefore contra-indicated in patients who have been treated with MAOIs within the last fourteen days.

The anticholinergic properties of chlorphenamine may cause drowsiness, dizziness, blurred vision and psychomotor impairment in some patients which may seriously affect ability to drive and use machinery.

Chlorphenamine, in common with other drugs having anticholinergic effects, should be used with caution in epilepsy; raised intra-ocular pressure including glaucoma; prostatic hypertrophy; severe hypertension or cardiovascular disease; bronchitis, bronchiectasis and asthma; hepatic disease and thyrotoxicosis. Children and the elderly are more likely to experience the neurological anticholinergic effects.

The effects of alcohol may be increased.

Concurrent use of chlorphenamine and hypnotics or anxiolytics may potentiate drowsiness. Concurrent use of alcohol may have a similar effect. Chlorphenamine inhibits phenytoin metabolism and can lead to phenytoin toxicity. The anticholinergic effects of chlorphenamine are intensified by MAOIs (see Contra-indications).

There is inadequate evidence of safety in human pregnancy. Piriton Tablets should only be used during pregnancy when clearly needed and when the potential benefits outweigh the potential unknown risks to the foetus. Use during the third trimester may result in reactions in neonates.

It is reasonable to assume that chlorphenamine maleate may inhibit lactation and may be secreted in breast milk. The use of Piriton preparations in mother's breast feeding their babies requires that the therapeutic benefits of the drug should be weighed against the potential hazards to the mother and baby.

The anticholinergic properties of chlorphenamine may cause drowsiness, dizziness, blurred vision and psychomotor impairment, which can seriously hamper the patients' ability to drive and use machinery.

Sedation varying from slight drowsiness to deep sleep. The following may also occasionally occur: inability to concentrate; lassitude; blurred vision; gastro-intestinal disturbances such as anorexia, dyspepsia, nausea, vomiting, diarrhoea and abdominal pain; hepatitis including jaundice; urinary retention; headaches; dry mouth; dizziness; palpitation; tachycardia; arrythmias; hypotension; chest tightness; thickening of bronchial secretions; haemolytic anaemia and other blood dyscrasias; allergic reactions including exfoliative dermatitis, photosensitivity and urticaria; twitching, muscular weakness and inco-ordination; tinnitus; depression, irritability and nightmares.

Children and the elderly are more likely to experience the neurological anticholinergic effects.

The estimated lethal dose of chlorphenamine is 25 to 50 mg/kg body weight. Symptoms and signs include sedation, paradoxical stimulation of CNS, toxic psychosis, seizures, apnoea, convulsions, anticholinergic effects, dystonic reactions and cardiovascular collapse including arrhythmias.

Symptomatic and supportive measures should be provided with special attention to cardiac, respiratory, renal and hepatic functions and fluid and electrolyte balance.

Treatment of overdosage should include gastric lavage or induced emesis using Syrup of lpecacuanha. Following these measures activated charcoal and cathartics may be administered to minimise absorption.

Hypotension and arrhythmias should be treated vigorously. CNS convulsions may be treated with i.v. diazepam or phenytoin. Haemoperfusion may be used in severe cases.

Chlorphenamine maleate is a potent antihistamine (H₁-antagonist).

Chlorphenamine is well absorbed from the gastro-intestinal tract, following oral administration. The effects develop within 30 minutes, are maximal within 1 to 2 hours and last 4 to 6 hours. The plasma half-life has been estimated to be 12 to 15 hours.

Chlorphenamine is metabolised to the monodesmethyl and didesmethyl derivatives. About 22% of an oral dose is excreted unchanged in the urine. Only trace amounts have been found in the faeces.

No additional data of relevance.

Lactose

Maize Starch

Yellow Iron Oxide (E172)

Magnesium Stearate

Purified Water

None reported.

3 years.

Store below 30°C.

The tablets are blister packed and supplied in cartons of 30 or 60 tablets.

For detailed instructions for use refer to the Patient Information Leaflet in every pack.

Stafford Miller Limited

980 Great West Road

Brentford

Middlesex TW8 9GS

UNITED KINGDOM

Trading as: GlaxoSmithKline Consumer Healthcare, Brentford, TW8 9GS, UK.

PL 00036/0091

14 February 1997

21 November 2007