As with other antipsychotics, caution is advised when prescribing risperidone with medicinal products known to prolong the QT interval, e. g., class Ia antiarrhythmics (e. g., quinidine, dysopiramide, procainamide), class III antiarrhythmics (e. g., amiodarone, sotalol), tricyclic antidepressants (i. e., amitriptyline), tetracyclic antidepressant (i. e., maprotiline), some antihistaminics, other antipsychotics, some antimalarials (i. e., chinice and mefloquine), and with medicines causing electrolyte imbalance (hypokalaemia, hypomagnesiaemia), bradycardia, or those which inhibit the hepatic metabolism of risperidone.