What drugs can cause Torsades de Pointes?

Hello, I'm a healthcare professional with expertise in pharmacology. Torsades de Pointes is a type of ventricular tachycardia that can be life-threatening, and it's often associated with a specific type of abnormal heart rhythm known as a long QT syndrome. Several drugs have been identified to potentially cause Torsades de Pointes, particularly those that prolong the QT interval on an electrocardiogram (ECG). Here's a list of some classes of drugs and specific medications that are known to carry this risk: 1. Antiarrhythmic drugs: Class IA (e.g., quinidine, disopyramide) and Class III (e.g., sotalol, dofetilide, amiodarone). 2. Antimicrobials: Macrolides (e.g., erythromycin, azithromycin), fluoroquinolones (e.g., moxifloxacin, levofloxacin), and antifungals (e.g., ketoconazole). 3. Psychotropic drugs: Antipsychotics (e.g., haloperidol, thioridazine), tricyclic antidepressants (e.g., amitriptyline), and some selective serotonin reuptake inhibitors (SSRIs) like citalopram and sertraline. 4. Gastrointestinal drugs: Some prokinetics (e.g., cisapride, which is no longer available in many countries due to this risk). 5. Antihistamines: First-generation antihistamines (e.g., diphenhydramine) can prolong the QT interval. 6. Others: Some antiemetics (e.g., ondansetron), anesthetics (e.g., droperidol), and drugs used for Parkinson's disease (e.g., methadone). It's important to note that not all patients taking these medications will experience Torsades de Pointes, and the risk can be influenced by other factors such as dosage, duration of treatment, underlying heart conditions, and the presence of electrolyte imbalances, particularly hypokalemia and hypomagnesemia.

It has also been shown as a side effect of certain anti-arrhythmic medications, such as sotalol, procainamide, and quinidine. The gastrokinetic drug cisapride (Propulsid) was withdrawn from the US market in 2000 after it was linked to deaths caused by long QT syndrome-induced torsades de pointes.