8-Chloro-6-[(1-isopropyl-3-imidazolin-2-yl)-methyl]-1,6-benzoperhydrothiazocin-hydrochloride (
dazolicin, ucb B 192) is a new
antiarrhythmic drug with direct membrane action which was applied both orally and parenterally. The immediate antiarrhythmic effect of a single i.v. injection of 150 mg of
dazolicin on the average was investigated in 28 patients with various types of
arrhythmia. After i.v. injection the
drug proved to have very strong antiarrhythmic potency and rather a low incidence of side effects. Ectopic beats and
paroxysmal tachycardias of both ventricular and supraventricular origin were successfully treated with
dazolicin. The
antiarrhythmic drug significantly increased the duration of both the QRS- and QT-interval after correction for frequency but it had no detectable effects on the atrioventricular conduction time. After i.v. administration the antiarrhythmic effects of the
drug lasted for several hours. The elimination half-life of
dazolicin was 7 h. Oral treatment with
dazolicin was attempted in 10 patients suffering from stable extrasystolic
arrhythmia with daily doses ranging from 3 x 25 mg to 3
x 50 mg. In only 4 patients ectopic beats could sufficiently be eliminated. According to the low dosage the maximum serum concentrations after oral application were significantly lower than after i.v. injection. In two patients serious side effects were observed, such as
paroxysmal ventricular fibrillation and an increase in frequency and polymorphism of
ventricular ectopic beats. In both instances the patients were suffering from
congestive heart failure and they had TU abnormalities in the ECG.