Does desloratadine alter the serum levels of montelukast when administered in a fixed-dose combination?

OBJECTIVES/HYPOTHESIS The aim of this study was to investigate the serum levels of montelukast when administered alone or in combination with desloratadine. STUDY DESIGN A prospective crossover study. METHODS Twenty-three healthy volunteers were investigated in two sessions. Volunteers were given 10 mg of montelukast orally with 250 mL water in the first session. The same subjects were given 10 mg of montelukast in fixed combination with 5 mg desloratadine 10 days after first session. Blood samples were collected 2, 3, and 4 hours after drug administration, and kept at -80°C after both applications. Plasma samples were analyzed for montelukast concentration. RESULTS Mean concentration values of both groups were not statistically different (P > .05), but the differences were statistically significant according to time (P < .05). Statistically significant difference was not found between the groups according to the area under curve on the basis of both marginal and cumulative values for all different time intervals (P > .05). CONCLUSIONS The absorption rate of montelukast was not altered when administered with desloratadine. This study suggested that desloratadine does not influence the bioavailability of montelukast, and their combination therapy can be used safely.