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BackgroundPhosphodiesterase 4 (PDE4) inhibitors increase intracellular cyclic adenosine monophosphate (cAMP), leading to regulation of inflammatory cell functions. Roflumilast is a potent and targeted PDE4 inhibitor. The objective of this study was to evaluate the effects of roflumilast on bronchoconstriction, airway hyperresponsiveness (AHR), and airway inflammation in mild asthmatic patients undergoing allergen inhalation challenge.Methods25 subjects with mild allergic asthma were randomized to oral roflumilast 500 mcg or placebo, once daily for 14 days in a double-blind, placebo-controlled, crossover study. Allergen challenge was performed on Day 14, and FEV1 was measured until 7 h post challenge. Methacholine challenge was performed on Days 1 (pre-dose), 13 (24 h pre-allergen), and 15 (24 h post-allergen), and sputum induction was performed on Days 1, 13, 14 (7 h post-allergen), and 15.ResultsRoflumilast inhibited the allergen-induced late phase response compared to placebo; maximum % fall in FEV1 (p = 0.02) and the area under the curve (p = 0.01). Roflumilast had a more impressive effect inhibiting allergen-induced sputum eosinophils, neutrophils, and eosinophil cationic protein (ECP) at 7 h post-allergen (all p = 0.02), and sputum neutrophils (p = 0.04), ECP (p = 0.02), neutrophil elastase (p = 0.0001) and AHR (p = 0.004) at 24 h post-allergen.ConclusionsThis study demonstrates a protective effect of roflumilast on allergen-induced airway inflammation. The observed attenuation of sputum eosinophils and neutrophils demonstrates the anti-inflammatory properties of PDE4 inhibition and supports the roles of both cell types in the development of late phase bronchoconstriction and AHR.Trial RegistrationClinicalTrials.gov: NCT01365533

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Background: Roflumilast, an oral, once-daily phosphodiesterase 4 inhibitor, is currently in clinical development for the treatment of asthma. Objectives: This pilot study examined the effect of roflumilast on allergen-induced airway hyperresponsiveness (AHR) to histamine challenge and asthmatic response to allergen challenge. Methods: In a randomized, double-blind, 2-period, crossover trial, 13 patients with mild allergic asthma [mean forced expiratory volume in 1 s (FEV₁) % predicted = 86%] received a single dose of oral roflumilast 1,000 µg or placebo. Patients were administered roflumilast 60 min before allergen challenge, and asthmatic responses were assessed via change in FEV₁ ≤9 h after allergen challenge. AHR to histamine provocation was measured before and repeated 24 h after allergen provocation. Patients inhaled histamine in doubling concentrations until attaining a decrease in FEV₁ of ≤20% (PC₂₀FEV₁). Results: Roflumilast had no detectable bronchodilator activity 60 min after administration. Roflumilast significantly attenuated AHR compared with placebo, with a mean change in pre- to postallergen challenge PC₂₀FEV₁ ratio of 1.23 ± 2.75 and 2.51 ± 2.95 for roflumilast and placebo, respectively (p = 0.002). During the late asthmatic response, roflumilast reduced the mean maximum decrease in FEV₁ from 2 to 9 h after allergen challenge compared with placebo (p = 0.005). Additionally, FEV₁ at 9 h after challenge was significantly higher in patients treated with roflumilast (p = 0.03). Early asthmatic responses to allergen challenge were not significantly reduced by the single dose of roflumilast. Conclusions: Roflumilast attenuated allergen-induced AHR in patients with mild asthma. These results support further investigation of roflumilast as an anti-inflammatory treatment of asthma.

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