Moderate
Bisoprolol × Theophylline
Selective beta-adrenergic blockers×Methylxanthine
Mechanism
Bisoprolol is cardioselective, but at high doses (above 10 mg/day) partially blocks β2-receptors and may weaken theophylline's bronchodilator effect in asthma or COPD.
Symptoms
Return of dyspnoea, wheezing, night cough. In severe asthma, bronchospasm is possible.
Management
In mild asthma or COPD, bisoprolol up to 10 mg is acceptable with pulmonary function monitoring. In severe airway obstruction, replace bisoprolol with a non-β2 cardiovascular alternative (amlodipine, ivabradine in heart failure with tachycardia).