LG 6-101 (1-[3-(2-methoxy-3-(2-methylpropylamino)-propoxy)-4-methyl- 2-thienyl]-3-phenyl-1-propanone, hydrochloride) and
LG 6-102 (2-(2-methoxy-3-propylamino-propoxy)-3-phenyl-propiophenone, hydrochloride) are two new
antiarrhythmic drugs. They are structurally related to
propafenone which is a widely used class 1
antiarrhythmic drug with relatively low bioavailability. Both substances were characterized in four animal models of
arrhythmia and compared to
propafenone. In isolated guinea pigs left auricles
LG 6-101 and LG6-102 were about twice as effective as
propafenone regarding the prolongation of the functional refractory period but did not decrease contractility more than
propafenone.
LG 6-101 was significantly more effective (p less than or equal to 0.002) than
propafenone or
LG 6-102 in delaying the onset of ventricular
premature beats in
ouabain induced arrhythmias in guinea pigs. In
aconitine induced arrhythmias in rats,
LG 6-101 and
LG 6-102 did not differ in their antiarrhythmic effects from
propafenone, whereas the protection against
cardiac arrest was significantly (p less than or equal to 0.003) better for
LG 6-101 than for
propafenone or
LG 6-102. In arrhythmias induced by occlusion of the left descending coronary artery in rats the drugs tested showed as good antiarrhythmic effects as
propafenone. In this model the size of the ischemic area was also measured and
LG 6-101 was the most effective
drug in that respect. These results suggest that both
LG 6-101 and
LG 6-102 are potent antiarrhythmic substances which in some models were more effective than
propafenone.