We evaluated the effects of chronic dosing with fexofenadine (FEX) and montelukast (ML) at clinically recommended doses in inhaled corticosteroid (ICS) treated asthmatics using adenosine monophosphate (AMP) bronchial challenge as the primary outcome variable.

18 atopic asthmatic patients receiving mean ICS of 631μg daily which remained unchanged throughout the study, were randomized in double-blind, cross-over fashion to receive for 1 week either FEX 180mg, ML 10mg or placebo (PL). There was a 1-week washout period prior to each randomized treatment. AMP PC₂₀ measurements were made after each washout and randomized treatment period.

Washout values for AMP PC₂₀ (mg/ml) prior to each randomized treatment were not significantly different: 74 vs. 73 vs. 71 for FEX, ML and PL respectively. There were significant improvements (p<0.05) in AMP PC₂₀ vs. PL (78); with FEX (127), and ML (121). Spontaneous recovery after AMP challenge as area under the curve (%.min) was significantly enhanced (p<0.05) with ML (352) vs. FEX (758), and vs. PL (683). Both FEX and ML significantly suppressed (p<0.05) levels of exhaled nitric oxide while only ML significantly reduced (p<0.05) the peripheral blood eosinophil count vs. PL. Morning and evening peak expiratory flow were significantly higher (p<0.05) and albuterol rescue were significantly reduced (p<0.05) with FEX and ML, vs. PL.

Chronic dosing with FEX and ML as add-on therapy improved AMP PC₂₀ and other surrogate inflammatory markers along with asthma diary outcomes in ICS treated atopic asthmatics. Further studies are indicated to evaluate long-term add-on effects of FEX on exacerbations.