Loctril 10 mg Tablet, manufactured by OSL Pharma Limited, is primarily used for the prophylaxis and chronic treatment of asthma in patients aged 12 months and older. It is also indicated for the acute prevention of exercise-induced bronchoconstriction in patients aged 6 years and older, and for the relief of symptoms of allergic rhinitis, including seasonal and perennial types. The active ingredient, Montelukast Sodium, selectively inhibits the cysteinyl leukotriene receptor (CysLT1), thereby preventing the effects of leukotrienes that contribute to inflammation and bronchoconstriction. This medication is typically taken once daily, in the evening, with or without food. Common side effects may include headache, abdominal pain, and fatigue. It's important to note that Loctril is not intended for the relief of acute asthma attacks and should be used as part of a comprehensive asthma management plan under the guidance of a healthcare professional.