Cardiotoxic effects resulting from the interaction between risperidone and thiazide diuretics

We reported a case of a 48 years old man with history of persecutory delusion after being threatened at work, treated with risperidone and paroxetine. Since there was no improvement, the doses were increased and the patient showed QTc-interval prolongation, with a T-wave amplitude decrease and an increase on the U-wave, in addition to hypokalemia. Besides, the patient was hypertensive and was using hydrochlorothiazide. Risperidone has the potential to block the fast component of the cardiac potassium channel and it extends the repolarization process of the ventricles, which can lead to torsade de pointes, sudden cardiac death and arrhythmias. Also hydrochlorothiazide can cause hypokalemia, with disturbances on the myocardium depolarization and repolarization. There was a serious drug interaction with two potentially arrhythmogenic drugs, which led to the alterations on the electrocardiogram and generated hurtful symptoms to the patient. The shift of the atypical antipsychotic to one typical and of the hydrochlorothiazide to a diuretic that does not cause hypokalemia brought improvements to the patient.
Source: Jornal Brasileiro de Psiquiatria - Category: Psychiatry Source Type: research