Ketotifen – Uses

Background

Ketotifen is a benzocycloheptathiophene derivative with potent antihistaminic and mast cell stabilizing properties. It has a similar structure to some other first-generation antihistamines such as cyproheptadine and azatadine.

Ketotifen was first developed in Switzerland in 1970 by Sandoz Pharmaceuticals and was initially marketed for the treatment of anaphylaxis. In the US, it is now used in an over-the-counter ophthalmic formulation for the treatment of itchy eyes associated with allergies, and in Canada a prescription-only oral formulation is available and indicated as an add-on therapy for children with atopic asthma. In addition, oral ketotifen is used in Mexico and across Europe for the treatment of various allergic symptoms and disorders, including urticaria, mastocytosis, and food allergy.

Properties and Characteristics of Ketotifen

Drug class	Antihistamines
Brand Names	Zaditor, Alaway, Claritin Eye, Eye Itch Relief
Synonyms	Ketotifen, Ketotifene, Ketotifeno, Ketotifenum
Molecular Formula	C₁₉H₁₉NOS
Molecular Weight	309.4 g/mol
IUPAC Names	2-(1-methylpiperidin-4-ylidene)-6-thiatricyclo[8.4.0.0^{3,7}]tetradeca-1(14),3(7),4,10,12-pentaen-8-one
Structural formula of main components
Pure active ingredient	Ketotifen
Appearance	Crystals
Melting point	304 to 307 °F
Solubility	Readily soluble in water, 15.3 mg/L at 25 °C
Excretion	Urinary excretion
Available forms	Solution, Tablet, Syrup
Storage	Should store this material in a refrigerator
Prescription	Doctor prescription is required

Ketotifen Uses

This drug is used to prevent and treat allergic/seasonal conjunctivitis, which causes scratching in the eyes. Ketotifen is an antihistamine for the eyes that works by blocking a natural product that causes allergic symptoms (histamine). It’s also a mast cell stabilizer, which helps to avoid allergic reactions by reducing the release of natural compounds that cause them. Also, the drug works by preventing the release of certain chemical messengers that can cause inflammation, airway spasms, and other asthma and allergy symptoms.

Ketotifen is a long-term medication for children with asthma to avoid or reduce wheezing and troubled breathing. It is commonly used in conjunction with other asthma drugs (including corticosteroids such as prednisone, inhaled beta-agonists such as salbutamol).

What are the side effects of Ketotifen?

Some of the common side effects of Ketotifen are:

Headaches.
Runny nose.
Eye pain.
Burning in the eyes.
Itching.
Blurriness in vision.
Rashes.
Increased sensitivity to light.
Pain in the stomach.
Dizziness.
Drowsiness.
Irritation.

The medication may include inactive chemicals that cause severe allergic reactions or other issues. Therefore, do not hesitate to consult the medical experts.

Mechanism of action

The precise mechanism(s) through which ketotifen exerts its therapeutic effects are unclear. Ketotifen 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.

Interactions with medicines

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

Amifampridine
Bupropion
Donepezil
Pitolisant

Interactions with Food/Tobacco/Alcohol

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.

Dosing

The dose of this medicine will be different for different patients. Follow your doctor’s orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

For oral dosage form (tablets and syrup)

For asthma:

Adults and children 3 years of age and older—The usual dose is 1 milligram (mg) (1 tablet or 5 milliliters [mL] of syrup) twice daily, once in the morning and once in the evening.
Infants and children from 6 months to 3 years of age—Dose is based on body weight and must be determined by the doctor. It is usually 0.25 mL (50 mcg or 0.05 mg) of syrup per kilogram (kg) (110 micrograms [mcg] or 0.110 mg per pound) of body weight twice daily, once in the morning and once in the evening.

For itchy eyes:

If you are using ketotifen eye drop then follow your doctor’s advice. Apply 1 drop to the affected eye(s) twice a day (every 8 to 12 hours) or as instructed by your doctor or follow the package instructions. Dosage is determined by your medical condition and treatment reaction. Before applying eye drops, make sure your hands are clean. Do not touch the dropper tip or allow it to come into contact with your eye or any other surface to prevent contamination. Remove your contact lenses before using the eye drop. Apply 1 drop in the lower eyelid and look downward. Gently close your eyes for 1 to 2 minutes.

Overdose

Overdose of an eye drop can lead to severe side effects like headache, eye irritation and dry eyes. Talk with your doctor immediately if you think you have used too much of this medicine.

Symptoms of overdose

Get emergency help immediately if any of the following symptoms of overdose occur:

Blurred vision
Confusion
Convulsions
Disorientation
Dizziness
Drowsiness (severe)
Faintness or lightheadedness when getting up from a lying or sitting position
Fast, pounding, or irregular heartbeat or pulse
Hyperexcitability
Loss of consciousness
Palpitations
Sweating
Unusual tiredness or weakness

What special precautions should I follow?

Before using ketotifen eye drops,

Tell your doctor and pharmacist if you are allergic to ketotifen or any other medications.
Tell your doctor and pharmacist what prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking.
You should know that you should not wear contact lenses if your eye(s) is/are red. If your eyes are not red and you wear contact lenses, you should know that ketotifen solution contains benzalkonium chloride, which can be absorbed by soft contact lenses. Remove your contact lenses before instilling ketotifen and put them back in 10 minutes later.

Pregnancy & Breastfeeding

During pregnancy, if you are using this drug then talk with your doctor immediately. The drug should be used if the benefits outweigh the risks. Ketotifen eye drop doesn’t have any side effects while breastfeeding. But before using any medication talk with your doctor immediately.

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