Piriton Allergy Tablets are used to help relieve the symptoms of some allergies and itchy skin rashes
Therapeutic indications
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.
Posology and method of administration
Adults:
1 tablet 4 to 6 hourly (daily max: 24 mg).
Children aged 6 - 12 years:
½ tablet 4 to 6 hourly (daily max: 12 mg).
Elderly:
As in adults but such patients are prone to confusional psychosis and other neurological anticholinergic effects.
Contraindications
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.
Special warnings and precautions for use
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.
Interaction with other medicinal products and other forms of interaction
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
Pregnancy and lactation
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.
Effects on ability to drive and use machines
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.
Undesirable effects
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
