WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT• Ivabradine is a new heart rate-lowering agent that acts specifically on the sinoatrial node via the If pacemaker channels.• Ivabradine has demonstrated similar efficacy to b-blockers.• As b-blockers are contraindicated in patients with obstructive airway disease, this study was conducted to assess the safety of ivabradine in patients with asthma. WHAT THIS STUDY ADDS• This study demonstrates that ivabradine has no effect on the pulmonary functions in patients with asthma and can be safely used a heart rate-lowering agent in patients with angina and coexistent airflow obstruction. AIMb-Blockers are commonly prescribed for stable angina and are recommended as initial therapy. However, b-blockers are contraindicated in patients with obstructive airway disease because of a risk of bronchoconstriction. Ivabradine is a specific heart rate-lowering agent that acts via If pacemaker channels in the sinoatrial node with no b-adrenoreceptor activity. Ivabradine has been recently approved for the treatment of stable angina. This study assessed the effects of repeated administration of ivabradine on lung function in patients with asthma. METHODSIn this double-blind, placebo-controlled, crossover study, 20 subjects with asthma received either oral ivabradine 10 mg b.i.d. or placebo for 4.5 days. Forced expiratory volume in 1 s (FEV1) and peak expiratory flow rate (PEFR) were designated as the main outcome variable. Diary cards were used to monitor asthma symptoms on a five-point scale, rescue medication usage, and adverse events. RESULTSThere were no significant differences in mean variation of FEV1 (ivabradine P = 0.664; placebo P = 0.652) or PEFR (ivabradine P = 0.153; placebo P = 0.356) from baseline following administration of ivabradine. There was also no significant difference in maximum percent variation in FEV1 or PEF between treatment groups (P = 0.994; FEV1 and P = 0.704; PEF). On a similar note, there was no significant difference in asthma symptoms or rescue medication usage reported between the two groups. Adverse events were generally mild-to-moderate in intensity and no cardiovascular or serious adverse events were recorded. CONCLUSIONSThis study confirms that ivabradine does not affect respiratory function or symptoms in patients with asthma and therefore represents a valuable therapeutic alternative to b-blockers for treating patients with stable angina and asthma.