Bioequivalence of 2 formulations of montelukast (5 mg chewable tablet) in the fasting state: an open-label randomized, single-dose, 2-period, crossover study

Introduction: Montelukast, a selective and active leukotriene receptor antagonist, is one of the most common agents in asthma treatment for both adults and children. Objective: To assess whether the pharmacokinetic profiles of two formulations of montelukast were similar after a single 5 mg dose (chewable tablets), administered orally under fasting conditions, sampling blood before and 36 hours after administration. Methods: This was a randomized, 2-sequence, 2-period, crossover study of 2 chewable tablet formulations of the drug: Singulair Merck Sharp and Dohme Farmacêutica Ltda. (reference), and generic montelukast, manufactured by Eurofarma Laboratórios S.A. (test). Plasma samples obtained from 35 participants were analyzed for montelukast through high-performance liquid chromatography coupled to tandem mass spectrometry, with montelukast-d6 as the internal standard. Peak montelukast concentrations were 299.313 (SD, 11.039) ng/mL for the reference formulation and 279.803 (SD, 10.085) ng/mL for test formulation. Results: Statistical analysis showed no significant differences between AUC0-36h, AUC0-inf, or Cmax between formulations, with the following test/reference ratios: 102.458 for AUC0-36h, 102.522 for AUC0-inf, and 93.490 for Cmax. No serious adverse events were reported during the trial. Our results demonstrated the bioequivalence of Singulair and Eurofarma’s generic montelukast. Conclusions: Our results revealed that the new generic tablets are clinically safe and can be used interchangeably with the brand name product. Eurofarma’s montelukast offers a safe, effective, and cheaper treatment option for people with asthma or allergic rhinitis.