Variations in potency of certain commercial preparations of digitalis

1. 1. Different lots of five commercial preparations of digitalis, marketed in ampules, have been biologically assayed by the cat method of Hatcher and Brody. 2. 2. Samples of all of the preparations so examined were found to be below the expected potency, as estimated in terms of a standard U. S. P. tincture. One lot of Digitan, however, was 97 per cent active. The newest preparation of Digalen, standardized by the manufacturer by the cat method, was 71 per cent stronger than its labeled biologic activity. 3. 3. In four instances, different lots of the same product showed wide variations in potency. 4. 4. Such variations in the strength of digitalis products marketed in ampules appear to indicate lack of adequate care on the part of the manufacturing drug firms in their preparation and labeling. The situation calls for prompt remedial measures. 5. 5. Two specimens of commercial digitalis tincture were found to be fully potent. One sample was 28 per cent stronger than its labeled activity. 6. 6. The one-hour frog method of digitalis assay, now official in the U. S. Pharmacopeia, has evidently not been found generally satisfactory for practical purposes, as evidenced by the continued use of cat, guinea pig and international units. It would be helpful both to the practitioners of medicine and to the drug manufacturers if a uniform standard were agreed upon and universally adopted in this country.