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[Paradoxic response to disopyramide and quinidine (author's transl)]
Zeitschrift Fur Kardiologie
|August 1, 1980
Summary
Disopyramide can cause severe ventricular arrhythmias even at normal doses, challenging previous beliefs. Patients with long QT intervals require careful monitoring when using this antiarrhythmic drug.
Area of Science:
- Cardiology
- Clinical Pharmacology
Background:
- Disopyramide is an antiarrhythmic medication.
- Previously, severe paradoxical reactions were thought to occur only at very high doses.
Observation:
- A case report details a 62-year-old female experiencing syncope due to ventricular tachycardia and flutter on a standard disopyramide regimen.
- The patient had a pre-existing long QT interval and was treated for intermittent atrial fibrillation.
- Similar adverse events occurred when the patient was later treated with quinidine sulfate.
Findings:
- This case, along with recent literature, indicates that severe paradoxical responses to disopyramide can occur at normal therapeutic doses.
- A review identified 20 patients with suspected or confirmed paradoxical reactions to disopyramide.
- Preexisting QT prolongation and hypokalemia are potential risk factors, though not universally present in reported cases.
Implications:
- Disopyramide should be prescribed with caution and under close monitoring, particularly in patients with risk factors like long QT intervals.
- The incidence of these severe side effects may be underestimated.
- Further research is needed to fully elucidate the mechanisms and risk factors for disopyramide-induced paradoxical arrhythmias.