Dronedarone hydrochloride (SR33589) is an amiodarone analog which has an effective and promising treatment for Atrial fibrillation.

Dronedarone reduces the incidence of early and delayed after depolarizations evoked by 1 mM Dofetilide and 0.2 mM Strophantidine in Purkinje fibres. Dronedarone (10 mM) markedly reduces the L-type calcium current (76.5%) and the rapid component of the delayed rectifier potassium current (97%) in ventricular myocytes. [1] Dronedarone inhibits the activity of I(K(ACh)) channels recorded from cell-attached patches by reducing the channel open probability (from 0.56 to 0.11) without modification of the single-channel conductance in single cells isolated from sinoatrial node (SAN) tissue of rabbit hearts. [2] Dronedarone exhibits a state-dependent inhibition of the fast Na(+) channel current with an IC50 of 0.7 μM in guinea pig ventricular myocytes, when the holding potential (V (hold)) is -80 mV. Dronedarone blocks Ca(2+) currents elicited by rectangular pulses at V (hold) = -40 mV with IC50 value of 0.4 μM, whereas at V (hold) = -80 mV, Dronedarone (10 μM) blocks only 20 % of the current. [3]

Dronedarone increases action potential duration in normal hearts of rats. Dronedarone reduces the late sustained K(+) current, I(K) (or Isus) by 69%. Dronedarone induces only a tonic block of I(K). Dronedarone induces a weak increase in the fast transient outward current, I(to), in rats after myocardial infarction. [4]