A. H. Robins Company, Incorporated

Thomas W Gero

Albert D Cale, Jr

Novel compounds of the formula: ##STR1## wherein R and R.sup.1 are C.sub.1 -C.sub.6 alkyl or cycloalkyl and R.sup.2 and R.sup.3 are independently selected from C.sub.1 -C.sub.6 alkyl or aryl or --NR.sup.2 R.sup.3 forms a heterocyclic group which may be further substituted are disclosed. These compounds were found to possess muscle relaxant properties.

2-(2-substituted

A method of treating cardiac arrhythmias and muscle tension and spasticity with N-(1-methyl-3-pyrrolidinyl)-1-(phenylmethyl)-1H-benzimidazol-2-amine and analogs and the pharmaceutical compositions are herein disclosed. Illustratively, the compound having the structure: ##STR1## corrects an induced arrhythmia in 7 out of 8 dogs at 7 mg/kg IV and has an ED.sub.50 of 21 mg/kg in the mouse Straub-tail test.

N-(1-methyl-3-pyrrolidinyl)-1-(phenylmethyl)-1H-benzimidazol-2-amine and

Novel compounds of the formula: ##STR1## Where R.sup.1 is loweralkyl and R.sup.2 and R.sup.3 are independently H, loweralkyl, aryl, or--NR.sup.2 R.sup.3 forms a heterocyclic group such as imidazole, morpholine, piperidine, or piperazine were found to exhibit cardiac arrhythmia correcting properties.

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Richmond, VA, United States of America

Thomas W Gero