THE POTENCY OF A NEW EXTRACT OF CONVALLARIA MAJALIS LEAVES

III. ASSAYS BY THE PAPILLARY MUSCLE PROCEDURE AND THE U.S.P. XII CAT METHOD

¹ From the Department of Physiology and Pharmacology, College of Pharmacy, University of Nebraska, Lincoln, Nebraska

1. A simplified modification of the apparatus devised by Gold and Cattell for testing the potency of cardiac drugs by their action on the isolated papillary muscle of the cat is presented.

2. The potency of a concentrated, purified, aqueous extract of the leaves of Convallaria majalis (Convara) was found equivalent to 6.1 ± 0.8 U.S.P. XI digitalis units per 0.1 gram by its activity on the isolated papillary muscle.

3. The potency of the same extract was found equivalent to 8.6 ± 0.6 U.S.P. XI (1936) digitalis units and 11.8 ± 0.6 U.S.P. XII (1942) digitalis units, respectively. per 0.1 gram by the U.S.P. cat method.

4. The U.S.P XII digitalis unit was about 79% the strength of the U.S.P. XI digitalis unit when tested by the cat method.