Five cardiology centers conducted open-label prospective trials of
meobentine sulfate, an intravenously and orally available analog of
bethanidine, to assess its potential for treatment of recurrent,
drug refractory
ventricular tachycardia (VT) or fibrillation (VF), and complex ventricular arrhythmias. The study population comprised 26 patients (mean age, 61 years); 18 were men.
Coronary artery disease was present in 15,
cardiomyopathy in six, and
valvular heart disease in three. Patients presented with both VT and VF (seven), sustained VT alone (12), or frequent ventricular ectopy (PVCs) and nonsustained VT (seven). Of the 26 patients, 5 were enrolled in antiarrhythmic studies (chronic
PVC suppression) and 21 were enrolled in programmed electrical stimulation (PES) studies. Two of five in the chronic
PVC study showed greater than 75%
arrhythmia suppression. Among 21 patients in PES studies, there were eight intravenous (16 mg/kg) and 19 oral trials (400 to 1000 mg every 6 hours, 3 days/dose interval). Five of 22 patients showed efficacy at repeat PES study (neither VT nor VF), one showed partial efficacy, and four were not restudied because of clinical
arrhythmia (three) and/or adverse effects (two). Overall, three patients (12%) were continued on the
drug for an extended period of time. Adverse experience included
hypotension in 50% and gastrointestinal effects (
nausea,
vomiting, or
diarrhea) in 56% (oral trials only). Adverse reactions led to
drug discontinuation in six and dosage reduction in eight patients. Thus,
meobentine may prevent induction of VT or VF or reduce frequency of complex PVCs in selected patients refractory to other antiarrhythmic agents, but the response rate is relatively low. Symptomatic
hypotension or gastrointestinal adverse effects are common and may limit utility of
meobentine as a chronic oral antiarrhythmic agent.