Description
Ketotifen has antiallergic properties and has been used similarly, to Sodium Chromoglycate in the prophylactic treatment of asthma. It also has the properties of an antihistamine. Ketotifen possesses marked anti-anaphylactic properties and is effective in preventing asthmatic attack. Ketotifen exerts sustained inhibitory effect on histamine reactions, which can be clearly dissociated from its antianaphylactic properties. Experimental investigations in asthmatic subjects have shown that Ketotifen is as effective orally as administered by inhalation as a selective mast cell stabiliser. Antihistamines were ineffective in those tests. The effectiveness of Ketotifen has been studied in long term clinical trials. Asthma attacks were reduced in number, severity and duration and in some cases, the patients were completely freed from attacks. Progressive reduction of corticosteroids and/or bronchodilators was also possible. The prophylactic activity of Ketotifen may take several weeks to become fully established. Ketotifen will not abort established attacks of asthma.
Indication
Ketotifen is indicated in the prophylactic treatment of bronchial asthma, symptomatic treatment of allergic conditions including rhinitis and conjunctivitis.
Pharmacology
Ketotifen is a potent anti-allergic substance possessing a powerful and sustained non-competitive histamine (H1) receptor blocking property. Ketotifen inhibits the release of mediators (e.g histamine, leukotrienes and prostaglandins) from cells responsible for type-(I) allergic reactions. Ketotifen also stabilizes mast cells, decreases chemotaxis, activation of degranulation of eosinophils.?ÿ?ÿAlso, it stabilizes mast cells & basophils and inhibits PAF (platelet activating factor) and is effective in preventing asthmatic attacks.
Dosage
Adults: 1 mg twice daily with food. If necessary the dose may be increased to 2 mg twice daily in severe cases. Children above 2 years: 1 mg twice daily with food. Patient??s known to be easily sedated should begin treatment with 0.5 to 1 mg at night for the first few days or as directed by the physician. Use in elderly: Same as adult dose or as advised by the physician.
Interaction
A reversible fall in the platelet count has been observed in a few patients receiving Ketotifen concomitantly with oral antidiabetics and it has been suggested that this combination should therefore be avoided. Since Ketotifen has the properties of the antihistamines, it may potentiate the effects of other CNS depressant drugs such as alcohol, antihistamines, hypnotics and sedatives.
Contradiction
A reversible fall in the platelet count has been observed in a few patients receiving Ketotifen concomitantly with oral antidiabetic agent and it has been suggested that this combination should therefore be avoided.
Side Effect
Drowsiness and in isolated cases, dry mouth and slight dizziness may occur at the beginning of treatment, but usually disappear spontaneously after a few days.
Pregnancy
Although there is no evidence of any teratogenic effect, Ketotifen in pregnancy and lactation is not recommended.
Precaution
It is important to continue the previous treatment for a minimum of two weeks after starting Ketotifen to avoid the possibility of exacerbation of asthma. This applies specially to systemic corticosteroids and ACTH because of the possible existence of adrenocortical insufficiency in steroid dependent patient. If intercurrent infection occurs, Ketotifen treatment must be supplemented by specific antimicrobial therapy. During the first day of treatment with Ketotifen, reactions may be impaired and patients should be warned not to take charge of vehicle or machinery until the effect of Ketotifen treatment on the individual is known. Patient should be advised to avoid alcoholic drinks. Ketotifen may potentiate the effects of sedatives, hypnotic, antihistamines and alcohol.
Overdose
Symptoms: Drowsiness, confusion, dyspnoea, bradycardia or tachycardia, disorientation, convulsions, severe hypotension, reversible coma.Management: Supportive and symptomatic.
Storage
Keep below 30?øC temperature, away from light & moisture. Keep out of the reach of children.