Bisoprolol × Dronedarone

Dronedarone has properties of all four Vaughan-Williams antiarrhythmic classes, including antiadrenergic activity (dronedarone SmPC). In healthy volunteers it lengthened the PR interval, meaning slower conduction from the atria to the ventricles, by about 12 ms at 400 mg twice daily (dronedarone label of the US Food and Drug Administration, FDA). Bisoprolol, as a beta-blocker, also slows the heart rate and conduction. In clinical studies bradycardia was seen more often when dronedarone was combined with beta-blockers (dronedarone SmPC).

Slow pulse, weakness, dizziness, fainting. On the electrocardiogram (ECG): bradycardia, PR prolongation, atrioventricular block.

The dronedarone SmPC says beta-blockers should be used with caution with dronedarone: start at a low dose and increase it only after an electrocardiogram (ECG) check. In patients already on a beta-blocker, record an ECG when dronedarone is started and adjust the beta-blocker dose if needed (dronedarone SmPC). The US Food and Drug Administration (FDA) gives the same rule: a low starting dose of the beta-blocker, increased only after the ECG confirms good tolerability (dronedarone FDA label). Dronedarone is contraindicated with a heart rate below 50 beats per minute and with second- or third-degree atrioventricular block without a pacemaker (dronedarone SmPC); bisoprolol is contraindicated with second- or third-degree atrioventricular block without a pacemaker and with symptomatic bradycardia (bisoprolol SmPC). During dronedarone treatment, record an ECG regularly, at least every 6 months (dronedarone SmPC).