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GlaxoSmithKline Consumer Healthcare (Ireland) Ltd

12 Riverwalk, Citywest Business Campus, Dublin 24, Ireland
E-mail: customer.relations@gsk.com
Medical Information Direct Line: 1800 441 442

Summary of Product Characteristics last updated on medicines.ie: 7/10/2015
SPC Piriton Tablets

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Piriton 4mg Tablets

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Each tablet contains 4mg Chlorphenamine maleate.

Excipients: contains lactose monohydrate 94.5mg

For a full list of excipients, see section 6.1.

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Yellow, circular, biconvex tablets with a breakline on both sides. They are engraved with a “P” to one side of the breakline, on one face.

The tablet can be divided into equal halves.

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4.1 Therapeutic indications

In the treatment of acute allergic reactions.

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4.2 Posology and method of administration

Oral use.

Do not exceed the stated dose or frequency of dosing.

Adults and children 12 years and over:

The usual dose is 1 tablet every 4 - 6 hours (maximum of 6 tablets in 24 hours).

In the elderly:

The usual dose is 1 tablet every 4 - 6 hours (maximum of 3 tablets in 24 hours).

Dosage should be as low as possible in view of greater susceptibility to anticholinergic central nervous system effects with a maximum of 12mg (3 tablets) in 24 hours.

Children 6 - 12 years:

The usual dose is 0.1mg/kg or ½ a tablet every 4 - 6 hours (maximum of 6 half tablets in 24 hours).

Children under 6 years:

Not recommended for children under the age of 6 years.

Renal impairment population

Medical advice should be sought for those with severe renal impairment.

Hepatic impairment population

Medical advice should be sought for those with severe hepatic impairment.

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4.3 Contraindications

1. Use in patients hypersensitive to the active ingredient or any other constituents.

2. Pre-coma states.

3. Use in patients who have been on recent MAO inhibitor therapy.

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4.4 Special warnings and precautions for use

This product may act as a cerebral stimulant in children and occasionally in adults, giving rise to insomnia, nervousness, hyperpyrexia, tremors and epileptiform convulsions.

Children and the elderly are more likely to experience the neurological anticholinergic effects and paradoxical excitation (e.g. increased energy, restlessness, nervousness).

The effects of alcohol may be increased.

Chlorphenamine, in common with other drugs having anticholinergic effects, should be used with caution in epilepsy, severe hypertension and cardiovascular disease, raised intra-ocular pressure including glaucoma; prostatic hypertrophy, severe hepatic impairment, severe renal impairment, bronchitis, thyrotoxicosis, bronchiectasis and bronchial asthma.

Chlorphenamine may increase the effects of alcohol and therefore concurrent use should be avoided.

Concurrent use with drugs which cause sedation such as anxiolytics and hypnotics may cause an increase in sedative effects, therefore medical advice should be sought before taking chlorphenamine concurrently with these medicines.

Should not be used with other anti-histamine containing products, including anti-histamine containing cough and cold preparations.

This medicinal product contains lactose. Patients with rare hereditary problems of galactose intolerance, the Lapp lactase deficiency or glucose-galactose malabsorption should not take this medicine.

Keep out of the reach and sight of children.

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4.5 Interaction with other medicinal products and other forms of interaction

Chlorphenamine may have an additive effect when used concurrently with hypnotics and anxiolytics causing potentiation of drowsiness. A similar additive effect will result from concurrent usage of alcohol with chlorphenamine.

The effects of anti-cholinergics e.g. some psychotropic drugs and atropine, may be potentiated by this product giving rise to tachycardia, mouth dryness, gastrointestinal disturbances e.g. dyskinesia, colic, urinary retention and headache.

As monoamine oxidase inhibitor therapy intensifies the anticholinergic effects of chlorphenamine, concurrent therapy is contra-indicated.

Chlorphenamine inhibits phenytoin metabolism and can lead to phenytoin toxicity.

4.6 Fertility, pregnancy and lactation

This product should not be used during pregnancy or lactation unless considered essential by the physician. Animal studies have not been conducted nor are there specific studies in human beings. Use during the third trimester may result in reactions in the newborn or premature neonates.

Small amounts of anti-histamines are excreted in breast milk.

Use by nursing mothers is not recommended because of the risks of adverse effects in the infant. Antihistamines may inhibit lactation.

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4.7 Effects on ability to drive and use machines

This product may cause drowsiness and patients receiving it should not drive or operate machinery unless it has been shown that their physical and mental capacity remains unaffected.

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4.8 Undesirable effects

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 trials 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:

Very rare: haemolytic anaemia, thrombocytopenic purpura. Other blood dyscrasias including agranulocytosis, anaemia, aplastic anaemia, eosinophilia, leucopenia and thrombocytopenia

Hepatobiliary disorders

Very rare: hepatitis including jaundice

Immune system disorders:

Unknown: allergic reactions, angioedema, anaphylactic reactions

Metabolism and nutritional disorders:

Unknown: anorexia

Psychiatric disorders:

Unknown: confusion*, excitation*, irritability*, nightmares*

Nervous system disorders*:

Very common: sedation, somnolence

Common: disturbance in attention, abnormal coordination, dizziness, headache

Eye disorders

Common: blurred vision

Vascular disorders:

Unknown: Hypotension

Respiratory, thoracic and mediastinal disorders:

Unknown: thickening of bronchial secretions

Gastrointestinal disorders:

Common: nausea, dry mouth

Unknown: vomiting, abdominal pain, diarrhoea, dyspepsia

Skin and subcutaneous disorders:

Unknown: exfoliative dermatitis, 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:

Common: fatigue

Unknown: chest tightness

*Children and the elderly are more susceptible to neurological anticholinergic effects and paradoxical excitation (e.g. increased energy, restlessness, nervousness).

Reporting of suspected adverse reactions

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 professional are asked to report any suspected adverse reactions via HPRA Pharmacovigilance, Earlsfort Terrace, IRL – Dublin 2; Tel: +353 1 6764971; Fax: +353 1 6762517. Website: www.hpra.ie; E-mail: medsafety@hpra.ie.

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4.9 Overdose

The estimated lethal dose of Piriton is 25 to 50mg/kg body weight.

Symptoms and Signs

Overdose is likely to result in effects similar to those listed under adverse reactions. 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. If overdosage is by the oral route treatment should include gastric lavage or induced emesis.

Following these measures activated charcoal and cathartics may be administered to minimise absorption. In cases of suspected overdose, symptomatic and supportive therapy should be given as appropriate.

Convulsions and marked CNS stimulation should be treated with parenteral diazepam.

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5.1 Pharmacodynamic properties

Mode of Action:

Chlorphenamine maleate is a potent antihistamine (H1-receptor antagonist). Antihistamines diminish or abolish the actions of histamine in the body by competitive reversible blockade of histamine 1 receptor sites on tissues.

Chlorphenamine also has anticholinergic activity.

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

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5.2 Pharmacokinetic properties

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.

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5.3 Preclinical safety data

No preclinical data presented.

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6.1 List of excipient(s)

Lactose monohydrate

Maize starch

Pregelatinised maize starch

Yellow iron oxide (E172)

Magnesium stearate

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6.2 Incompatibilities

Not applicable.

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6.3 Shelf life

3 years.

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6.4 Special precautions for storage

Do not store above 30°C.

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6.5 Nature and contents of container

Piriton Tablets are supplied in polypropylene containers (securitainers) of 500, with tamper-evident snap-on polyethylene lids or cartons of 30, containing three blister packs of 10 tablets or two blister packs of 15 tablets, cartons of 45 containing 3 blister packs of 15 tablets or cartons of 60 containing 4 packs of 15 tablets. The packs comprise PVDC coated white opaque PVC blisters, sealed with hard-temper aluminium foil by means of a heat seal lacquer.

Not all pack sizes may be marketed.

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6.6 Special precautions for disposal and other handling

No special requirements.

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GlaxoSmithKline Consumer Healthcare (Ireland) Limited,

12 Riverwalk,

Citywest Business Campus,

Dublin 24,


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PA 678/80/1

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Date of first authorisation: 10 June 1985

Date of last renewal: 10 June 2010

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July 2015

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Active Ingredients

   Chlorphenamine Maleate