PHOENIX Consider keeping hyaluronidase for injection on hand for repairing problems caused by hyaluronic acid fillers and not relying on compounded forms of hyaluronidase, Dr. Alastair Carruthers advised at a clinical dermatology conference sponsored by Medicis.
"Vitrase [hyaluro-nidase for injection] is a pure form of hyaluronidase, and it is of consistent efficacy," said Dr. Carruthers, clinical professor of dermatology at the University of British Columbia in Vancouver.
Compounded products might contain ingredients that cause reactions, he warned. They also are inconsistent in their activity.
"You can have up to a 10-fold difference in the activity, and clearly that is important," he said. "If you are using 10 units to get rid of a lump or 100 unitsthat is a big difference."
A naturally occurring protein enzyme, hyaluronidase makes connective tissue more permeable through hydrolysis of hyaluronic acid. "It eats hyaluronic acid," Dr. Carruthers said. Ista Pharmaceuticals in Irvine, Calif., manufactures Vitrase from the purified testicular hyaluronidase of sheep.
The Food and Drug Administration approved Vitrase for use in increasing the absorption and dispersion of other injectable drugs in 2004. The FDA reported the rate of adverse events, including allergic reactions, to be less than 1%. Because the drug could spread infection or inflammation, the FDA advised that it not be used in areas that are swollen by bites, stings, infection, or inflammation.
Using too much hyaluronidase for injection to correct a bump or other problem is not a concern, Dr. Carruthers said.
Hyaluronidase comprises only about 3% of human skin and it turns over in about 24 hours. "You can put in as much as you feel like, but typically maybe 20 units is enough to get rid of almost everything," he said.
Having hyaluronidase for injection on hand in the dermatology office "prevents problems," said Dr. Carruthers. He noted that vascular occlusion has been reported in rare cases with hyaluronic acid fillers.
Though cause and effect was not proven, he said occlusions have cleared after injection of large doses of hyaluronidase. "That is one of the reasons I have hyaluronidase in my office."
'You can putin as much [hyaluronidase] as you feel like, but typically maybe 20 units is enough.' DR. CARRUTHERS