• Montelukast is an oral leukotriene receptor antagonist. It has had a UK licence since 1998 as addon therapy for the treatment of patients, 6 years or older, with mild to moderate asthma inadequately controlled on ‘as required’ short-acting β-agonists and inhaled corticosteroids. It is also licensed for prophylaxis of asthma in which the predominant component is exercise-induced bronchoconstri...