International standard for tetracycline.

The International Standard for Tetracycline is a highly purified preparation of tetracycline hydrochloride. It was compared in a collaborative assay by 8 laboratories in 7 countries, with the working standard of the Food and Drug Administration of the US Department of Health, Education, and Welfare. On the basis of the results the International Unit for Tetracycline is defined as the activity contained in 0.00101 mg of the International Standard for Tetracycline, and is as nearly as possible equivalent to the activity of 1mug of pure tetracycline hydrochloride.