Psychoactive Drugs on Registry to Date

Fourteen psychoactive medications are listed on the registry of drugs that are either known to cause, or suspected of increasing a patient’s risk of, a potentially fatal cardiac arrhythmia called torsades de pointes.

The list of drugs for which cases of suspected drug-induced torsades de pointes are documented in the literature includes the antidepressants amitriptyline, desipramine, doxepin, and imipramine. Cases are also documented for the antipsychotics chlorpromazine and pimozide, both of which pose a higher risk of inducing arrhythmias in women than men.

Those drugs on the registry’s list shown to prolong the QT interval, and therefore increase theoretical risk for developing torsades de pointes, include the antidepressants fluoxetine and sertraline, although the association is not clear. A clearer link exists for the antidepressant venlafaxine and the antipsychotics haloperidol, mesoridazine, quetiapine, risperidone, and thioridazine.

The link between these drugs and the potential to cause harmful arrhythmias is thought to be due to the medications’ ability to alter electrolyte balances within the heart muscle cells. The result is a delay in the heart’s “resetting” of its electrolytes in anticipation of the next heartbeat. If the next heartbeat occurs without the electrolytes fully reset, the heartbeat may not conduct normally.

Psychiatric patients at highest risk of developing a drug-induced prolongation of the QT interval commonly have comorbid cardiovascular disease. In addition, risk increases with kidney or liver disorders and with age. Women are also at somewhat higher risk, simply because they generally have a longer QT interval than men. The most significant risk factor is the presence of multiple medications.