Ketotifen is an antihistamine drug that is used for the treatment of general allergy symptoms, certain allergic conditions (including conjunctivitis), and the management of asthma. When used for asthma, the drug is not regarded as effective for treating an immediate attack (it is not a rapid bronchodilator). Instead, over time its use is associated with a reduction in the frequency, duration, and severity of attacks. It is usually prescribed as a way to increase the efficacy of other asthma medications. Likewise, ketotifen fumarate will usually supplement an existing asthma medication program, and not replace the prescribing of immediate rescue devices such as an asthma inhaler or nebuliser.
Ketotifen fumarate alleviates allergy symptoms by blocking histamine H1 receptors, a property that is common to drugs of the antihistamine class. Its second and very unique mode of action, however, makes it useful in the treatment asthma. Ketotifen fumarate increases the concentration of beta-adrenergic receptors in the body (especially beta-2 receptors). Drugs that stimulate beta-2 receptors are commonly prescribed as bronchodilators, used to increase airflow to the lungs and counter the constriction caused by asthma. While potentially efficacious alone, one key therapeutic effect of ketotifen fumarate is to increase the sensitivity of the body to drugs of the beta agonist class.
The beta-2 receptor upregulating properties of ketotifen fumarate make this drug of interest to the bodybuilding and athletic communities. This is due to the strong role of the beta-2 receptor in supporting fat loss. Although not a strong fat loss compound by itself, when taken with a beta-2 agonist thermogenic like clenbuterol, ketotifen fumarate may increase thermogenic potency and noticeably extend the window of active lipolysis. Clenbuterol and other beta-2 agonists normally have a limited duration of usefulness here because beta-2-adrenergic receptors decrease in number with regular stimulation. Within several weeks of initiating therapy with such a drug, it usually begins to diminish in effectiveness. Ketotifen may extend this time period considerably.