- chlorphenamine maleate
This information is intended for use by health professionals
Piriton Allergy Tablets
Piriton Original Allergy Tablets
Round, biconvex, circular yellow tablets engraved with a P to one side of the breakline, with a breakline only on the reverse face. Each tablet contains 4 milligrams of chlorphenamine maleate.
Tablet. The tablet can be divided into equal doses.
The 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.
Oral Administration only
Do not exceed the stated dose or frequency of dosing
Adults and children over 12 years: 1 tablet 4 to 6 hourly. Maximum daily dose: 6 tablets (24mg) in any 24 hours.
Elderly: The elderly are more likely to experience neurological anticholinergic effects. Consideration should be given to using a lower daily dose (e.g. a maximum of 12mg in any 24 hours).
Children aged 6 - 12 years: ½ tablet 4 to 6 hourly. Maximum daily dose: 3 tablets (12mg) in any 24 hours.
Not recommended for children under the age of 6 years.
The 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). The tablets are therefore contra-indicated in patients who have been treated with MAOIs within the last fourteen days.
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 or asthma; hepatic impairment; renal impairment. Children and the elderly are more likely to experience the neurological anticho linergic effects and paradoxical excitation (eg. Increased energy, restlessness, nervousness).
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.
The effects of alcohol may be increased and therefore concurrent use should be avoided. Should not be used with other antihistamine containing products, including antihistamine containing cough and cold medicines.
Patients with rare hereditary problems of galactose intolerance, Lapp lactase deficiency or glucose-galactose malabsorption should not take this medicine.
Keep out of sight and reach of children.
Concurrent use of chlorphenamine and hypnotics or anxiolytics may cause an increase in sedative effects, therefore medical advice should be sought before taking chlorphenamine concurrently with these medicines.
Chlorphenamine inhibits phenytoin metabolism and can lead to phenytoin toxicity.
The anticholinergic effects of chlorphenamine are intensified by MAOIs (see Contra- indications).
There are no adequate data from the use of chlorphenamine maleate in pregnant women. The potential risk for humans is unknown. Use during the third trimester may result in reactions in the newborn or premature neonates. Not to be used during pregnancy unless considered essentially by a physician.
Chlorphenamine maleate and other antihistamine may inhibit lactation and may be secreted in breast milk. Not to be used during lactation unless considered essential by a physician.
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.
Specific estimation of the frequency of adverse events for OTC products is inherently difficult (particularly numerator data). Adverse reactions which have been observed in clinical trails and which are considered to be common (occurring in ≥1% to <10% of subjects) or very common (occurring in ≥10% of subjects) are listed below by MedDRA System Organ Class. The frequency of other adverse reactions identified during post- marketing use is unknown.
Blood and lymphatic system disorders
Unknown: haemolytic anaemia, blood dyscrasias
Immune system disorders:
Unknown: allergic reaction, angioedema, anaphylactic reactions
Metabolism and nutritional disorders:
Unknown: confusion*, excitation*, irritabilit y*, nightmares*, depression
Nervous system disorders*:
Very common: sedation, somnolence
Common: disturbance in attention, abnormal coordination, dizziness headache
Common: blurred vision
Ear and labyrinth disorders:
Unknown: palpitations, tachycardia, arrythmias
Respiratory, thoracic and mediastinal disorders:
Unknown: thickening of bronchial secretions
Common: nausea, dry mouth
Unknown: vomit ing, abdominal pain, diarrhoea, dyspepsia
Unknown: hepatitis, jaundice
Skin and subcutaneous disorders:
Unknown: exfo liative dermatit is, rash, urticaria, photosensitivity
Musculoskeletal and connective tissue disorders:
Unknown: muscle twitching, muscle weakness
Renal and urinary disorders:
Unknown: urinary retention
General disorders and administration site conditions:
Unknown: chest tightness
*Children and the elderly are more likely to experience the neurological anticho linergic effects and paradoxical excitation (eg. increased energy, restlessness, nervousness).
Reporting suspected adverse reactions after authorisation of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product. Healthcare professio nals are asked to report any suspected adverse react ions via the Yellow Card Scheme at:www.mhra.gov.uk/yellowcard.
Symptoms and signs
The estimated lethal dose of chlorphenamine is 25 to 50mg/kg body weight. Symptoms and signs include sedation, paradoxical excitation of the CNS, toxic psychosis, convulsions, apnoea, 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. If overdosage is by the oral route, treatment with activated charcoal should be considered provided there are no contraindications for use and the overdose has been taken recently (treatment is most effective if given within an hour of ingestion). Treat hypotension and arrhythmias vigorously. CNS convulsions may be treated with i.v. diazepam. Haemoperfusion may be used in severe cases.
ATC Code R06AB02
Chlorphenamine is a potent antihistamine (H1-antagonist).
Ant ihistamines diminish or abolish the actions of histamine in the body by co mpet it ive reversible blockade of histamine H1-receptor sites on tissues. Chlorphenamine also has ant icho linergic activit y.
Ant ihistamines act to prevent the release of histamine, prostaglandins and leukotrienes and have been shown to prevent the migration of inflammatory mediators. The actions of chlorphenamine include inhibit ion of histamine on smooth muscle, capillary permeabilit y and hence reduct ion of oedema and wheal in hypersensit ivit y react ions such as allergy and anaphylaxis.
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.
Yellow Iron Oxide (E172)
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.
GlaxoSmit hKline Consumer Healthcare (UK) Trading Limited,
980 Great West Road
14 February 1997 / 07 December 2005
980 Great West Road, Brentford, Middlesex, TW8 9GS
0800 783 8881
0800 783 8881