Antidysrhythmics amiodarone

The antidysrhythmic amiodarone (Cordarone) to the client in ventricular bigeminy on the telemetry monitor. 

In the Spanish Study of Sudden Death (SSD) amiodarone reduced all-cause mortality from 15.4 to 3.5% compared with metoprolol however, the mortality in those receiving no antidysrhythmic drugs at all was only 7.7%, and in those the effect of amiodarone was not significant (39). 

The incidence of cardiac dysrhythmias with amiodarone is under 3% (42), lower than with many other antidysrhythmic drugs, and several randomized controlled trials have failed to show any prodysrhythmic effect (43). 

The safety of antidysrhythmic drugs in children has not been thoroughly studied. However, the risk of prolongation of the QT interval seems to be considerably less than that in adults (226), although it has been reported with quinidine, disopyramide, amiodarone, sotalol, and diphemanil. 

Antidysrhythmic dmgs can themselves cause cardiac dysrhythmias, their major adverse effect. The risk of antidysrhythmic-induced cardiac dysrhythmias (prodys-rhythmic effects) has been estimated at about 11-13% in non-invasive studies (18,19) and at up to 20% in invasive electrophysiological studies. However, the risk varies from dmg to drug and is particularly low with class III drugs. In one study the quoted risks of dysrhythmias were flecainide 30%, quinidine 18%, propafenone 7%, sotalol 6%, and amiodar-one 0% (20). However, amiodarone does cause dysrhythmias, especially when the QT interval is over 600 ms. 

Because it prolongs the QT interval, bepridil can potentiate the effects of other drugs with the same effect (for example other Class I antidysrhythmic drugs and amiodarone). 

In conclusion, based on the results of an adequate series of clinical trials, dronedarone may be a useful alternative to amiodarone, with similar or slightly less antidysrhythmic efficacy, but significantly better tolerability. It is noteworthy that it seems to have no prodys-rhythmic effects and has definitely no thyrotoxic effect. Among its non-cardiac adverse effects, only a raised serum creatinine seems to be clinically relevant and deserves careful monitoring, particularly in patients with impaired renal function. 

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