35891-93-1

Tonocard(AstraZeneca).

Tocainide hydrochloride,2-amino-2＇ ,6 ＇-propionoxyxylidide hydrochloride (Tonocard)(pKa 7.7), is an analog of lidocaine. It is orally active and haselectrophysiological properties like those of lidocaine. Totalbody clearance of tocainide hydrochloride is only166 mL/min, suggesting that hepatic clearance is not large.Because of low hepatic clearance, the hepatic extraction ratiomust be small; therefore, tocainide hydrochloride is unlikelyto be subject to a substantial first-pass effect. The drug differsfrom lidocaine, in that it lacks two ethyl groups, which providestocainide hydrochloride some protection from first-passhepatic elimination after oral ingestion. Tocainide hydrochlorideis hydrolyzed in a manner similar to that of lidocaine.None of its metabolites is active.

Tocainide hydrochloride is classed as a IB antiarrhythmicagent and used orally to prevent or treat ventricular ectopyand tachycardia. The drug is given in 400- to 600-mgdoses every 8 hours.

Veterinary experience with tocainide is limited. At this time, dogs are the only veterinary species where enough clinical experience has been garnered to recommend its use. It is indicated for the oral therapy of ventricular arrhythmias, principally ventricular tachycardia and ventricular premature complexes. In humans, response to lidocaine can usually predict whether tocainide might be effective.