K Fen

Uses

K Fen is used for the prophylactic treatment of bronchial asthma, symptomatic treatment of allergic conditions including rhinitis and conjunctivitis.

K Fen 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. K Fen possesses marked anti-anaphylactic properties and is effective in preventing asthmatic attack. K Fen exerts sustained inhibitory effect on histamine reactions, which can be clearly dissociated from its antianaphylactic properties. Experimental investigations in asthmatic subjects have shown that K Fen is as effective orally as administered by inhalation as a selective mast cell stabiliser. Antihistamines were ineffective in those tests. The effectiveness of K Fen 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 K Fen may take several weeks to become fully established. K Fen will not abort established attacks of asthma.

K Fen eye drop is used for the treatment of signs & symptoms (itchy, watery, red & swollen eyes and eyelids) of allergic conjunctivitis including vernal kerato-conjunctivitis, vernal-keratitis, blepharitis, blepharo-conjunctivitis, and giant papillary conjunctivitis.

K Fen is also used to associated treatment for these conditions: Allergic Rhinitis (AR), Asthma, Allergic, Eye pruritus, Seasonal Allergic Conjunctivitis

How K Fen works

The precise mechanism(s) through which ketotifen exerts its therapeutic effects are unclear. K Fen is a potent and non-competitive antagonist of H1 histamine receptors, which is likely to be a significant contributor to its anti-allergic activity. In addition, ketotifen stabilizes mast cells and has demonstrated in vitro the ability to inhibit the release of allergic and inflammatory mediators such as histamine, leukotrienes C₄ and D₄ (i.e. SRS-A), and platelet-activating factor (PAF).

Other in vivo observations thought to contribute to ketotifen's efficacy in asthma include the inhibition of various PAF-mediated processes (e.g. airway hyperreactivity, eosinophil and platelet accumulation in the airways), prevention of leukotriene-induced bronchoconstriction, and suppression of eosinophil priming.

Dosage

K Fen 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.

Adults and children 3 years and older: 1 drop in the affected eye(s) twice daily, every 8-12 hours, not more than twice per day.

Children under 3 years of age: Consult with a doctor.

Side Effects

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.

Common side effects are burning, stinging, punctate corneal epithelial erosion, Blurring of vision upon drug instillation, dry eyes, eyelid disorder, conjunctivitis, eye pain, photophobia, subconjunctival haemorrhage.

Toxicity

Oral ingestion of up to 60x the recommended dose has been reported, although no fatal overdoses of ketotifen have been described. Symptoms of ketotifen overdosage may include significant sedation, confusion, disorientation, tachycardia, hypotension, convulsions, hyperexcitability (particularly in children), and/or reversible coma. If ingestion is recent, consider the use of gastric lavage or activated charcoal. Other treatments should be supportive and administered as necessary based on symptoms.

Physostigmine may be useful to mitigate anticholinergic effects, and short-acting barbiturates or benzodiazepines may be used if the patient presents with excitation or convulsions.

Precaution

It is important to continue the previous treatment for a minimum of two weeks after starting K Fen 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, K Fen treatment must be supplemented by specific antimicrobial therapy. During the first day of treatment with K Fen, reactions may be impaired and patients should be warned not to take charge of vehicle or machinery until the effect of K Fen treatment on the individual is known. Patient should be advised to avoid alcoholic drinks. K Fen may potentiate the effects of sedatives, hypnotic, antihistamines and alcohol.

The formulation of K Fen 0.025% eye drops contains benzalkonium chloride as a preservative, which may be deposited in soft contact lenses; therefore this eye drops should not be instilled while the patient is wearing lenses. The lenses should be removed before application of the drops and not reinserted earlier than 15 minutes after use.

Interaction

A reversible fall in the platelet count has been observed in a few patients receiving K Fen concomitantly with oral antidiabetics and it has been suggested that this combination should therefore be avoided. Since K Fen has the properties of the antihistamines, it may potentiate the effects of other CNS depressant drugs such as alcohol, antihistamines, hypnotics and sedatives.

If K Fen eye drops is used concomitantly with other eye medications there must be an interval of at least 5 minutes between the two medications.

Food Interaction

• Take with or without food. The co-administration of food does not significantly affect ketotifen disposition.

Elimination Route

Following oral administration, absorption is relatively quick (with a T_max of ~3 hours) and nearly complete as judged by plasma concentrations and urinary excretion levels - despite this, oral bioavailability is only ~50% due to a significant first-pass effect in the liver.

Half Life

K Fen clearance is biphasic - the half-life of the distribution phase is approximately 3-5 hours and the half-life of the elimination phase is 22 hours.

Elimination Route

More than 60% of an administered dose is excreted in the urine, primarily as metabolites - of this material, 5

Pregnancy & Breastfeeding use

Although there is no evidence of any teratogenic effect, K Fen in pregnancy and lactation is not recommended.

Contraindication

A reversible fall in the platelet count has been observed in a few patients receiving K Fen concomitantly with oral antidiabetic agent and it has been suggested that this combination should therefore be avoided.

Hypersensitivity to K Fen or any of the components

Acute Overdose

Symptoms: Drowsiness, confusion, dyspnoea, bradycardia or tachycardia, disorientation, convulsions, severe hypotension, reversible coma.

Management: Supportive and symptomatic.

No case of overdose has been reported. Oral ingestion of the contents of a 5 ml bottle would be equivalent to 1.25 mg of K Fen which is 60% of a recommended oral daily dose for a 3 years old child. Clinical results have shown no serious signs or symptoms after oral ingestion of up to 20 mg of K Fen.

Storage Condition

Store at 25° C.

Innovators Monograph

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