Hyaluronidase is an enzyme which degrades hyaluronan (HA) and has diverse clinical applications resulting from its ability to facilitate the dispersion and/or absorption of an array of medications and fluids. It provides rapid penetrance of anesthetic agents, particularly to locations difficult to access. In ophthalmology, hyaluronidase is used most often as an adjunct to local anesthesia for retrobulbar, peribulbar, or sub-Tenon’s blocks. The use of hyaluronidase in ophthalmology began as early as 1949, when Atkinson added it to retrobulbar and lid blocks.
Hyaluronidase has been used to facilitate the dispersion and/or absorption of fluids or medications for more than 70 years. It rapidly hydrolyzes HA, which is a glycosaminoglycan found in the extracellular matrix of most types of connective tissue (eg, skin, joint, cartilage). Connective tissue consists of many macromolecules, which serve as a barrier to bulk fluid flow through the interstitial matrix. HA is a mega-dalton molecule with a half-life of 15 to 20 hours in the skin. Interestingly, the half-life of HA in the circulation ranges between 2 and 5 minutes. When HA is broken down by hyaluronidase, it causes a transient increase in the permeability of the connective tissue. This increased permeability lasts for approximately 24 to 48 hours when a single subcutaneous (SC) 150-U dose of rHuPH20 is administered, after which there is no histologic change in collagen or sign of inflammation in animal models after 28 days.
WA-006 Rev 01/2018