Tiotropium in asthma - perspectives for the primary care physician

Asthma is a heterogeneous disease characterized by airway inflammation resulting from complex interactions between multiple hosts as well as environmental factors. As a chronic respiratory condition, asthma exerts a significant impact on patients and the healthcare system. Per the Global Initiative for Asthma (GINA), inhaled corticosteroids (ICS) with/without long-acting beta(2)-agonists (LABAs) should be used as the preferred controllers for the management of asthma. Despite a range of therapeutic options, many patients with asthma remain uncontrolled, resulting in an increased risk of hospitalization and emergency room visits and a worsened quality of life. Tiotropium (Spiriva (R), Boehringer Ingelheim Pharmaceuticals, Inc; 1.25 mu g, two puffs, once daily), delivered via the Respimat (R) inhaler (Boehringer Ingelheim Pharmaceuticals, Inc.), was the first long-acting muscarinic antagonist to be approved as an add-on maintenance treatment option for patients with asthma aged >= 6 years at GINA steps 4 and 5. By binding to the muscarinic receptors M1 and M3 in the bronchial airways, tiotropium antagonizes the action of acetylcholine, leading to smooth muscle relaxation and reduced mucus secretion. The efficacy and safety of tiotropium add-on to ICS +/- LABA maintenance treatment have been evaluated in randomized controlled trials (RCTs) involving patients with a range of asthma severities (mild, moderate, and severe) and across age groups (children, adolescents, and adults). Add-on tiotropium was found to be well tolerated and efficacious in all RCTs. Moreover, the findings from real-world studies complement results from RCTs, showing beneficial effects of tiotropium in reducing exacerbations, hospitalization, emergency room visits, and asthma worsening. In this review article, we discuss the pathophysiology of asthma and the role of tiotropium in the management of asthma from the perspective of a primary care physician.