Lorcainide is a new antiarrhythmic agent which effectively suppresses ventricular premature contractions. Its electrophysiological actions were studied in 15 cardiac patients with and without cardiac conduction abnormalities. In a dose of 2 mg/kg body weight, lorcainide decreased the sinus cycle length (SCL) and increased the corrected sinus node recovery time. The intra-atrial, atrioventricular (AV), and intraventricular conduction times were prolonged. A third-degree AV block developed in 2 patients with pre-existing conduction abnormalities. QRS widening showed that intramyocardial conduction was also affected. The effective refractory period of the atrioventricular node (ERP-AVN) was shortened, whereas the effect on the functional refractory period of the AVN was variable. The decrease in SCL and ERP-AVN may be due to a possible anticholinergic effect of the drug. The accessory pathway was blocked in 3 patients with a Wolff-Parkinson-White syndrome. The ERP of the ventricle was slightly prolonged. The electrophysiological profile of the drug, i.e., slowing of conduction velocity throughout the heart combined with shortening of SCL and ERP-AVN, differs from other antiarrhythmic agents.

Acetanilides↗

PubMedDate not supplied

Clinical electrophysiological properties of N-allyl-clonidine (ST 567) in man.

The electrophysiological properties of N-allyl-clonidine (ST 567) were studied in 18 patients. Four of these patients were pretreated with intravenous propranolol, 0.2 mg/kg, and atropine, 0.04 mg/kg, to induce autonomic blockade. ST 567 produces a sustained bradycardiac effect at a dose of 40 mg, i.v., in patients without (group I) and with (group II) autonomic blockade. The mean increase in Group I was 23% and in group II, 42%. The sinus node recovery time increased in both groups, from 1,151 +/- 73 to 1,310 +/- 81 msec in group I, and from 995 +/- 145 to 1,599 +/- 248 msec (means +/- SEM) in group II. The corrected sinus node recovery time was unaffected by ST 567 in Group I and increased from 165 +/- 50 to 427 +/- 117 msec in group II. The sinoatrial conduction time was unaffected by ST 567 in group I. The effective refractory period of the right atrium, the atrioventricular node and the right ventricle, as well as the functional refractory period of the atrioventricular node, were unaffected by ST 567 in patients without autonomic blockade. Intra-atrial, atrioventricular, and intraventricular conduction were also not altered by this drug. Thus, the electrophysiological profile of ST 567 differs from other bradycardia-inducing agents such as beta-blockers or calcium antagonists.

Adult↗

PubMedDate not supplied

[Pharmacokinetics and pharmacodynamics of the beta-receptor blocker sotalol].

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Adult↗