International standard for hyaluronidase.

The International Standard for Hyaluronidase is derived from a blend of four batches of bovine testicular hyaluronidase which had been purified so as to contain approximately 400 units per milligram. The material was mixed with beta-lactose, and lyophilized. Tablets were made from the dried mixture, and were examined extensively in the USA in order to establish their homogeneity and to relate their potency to the current USA "turbidity reducing unit" (TRU). On the basis of this examination, the International Unit for hyaluronidase is defined as the activity of 0.1 mg of the International Standard Preparation, and is very nearly equal to one TRU. It is recommended that the Standard be employed only for assaying testicular hyaluronidase, and that certain precautions be taken in its use.