In Vitro Resistance to Degradation of Hyaluronic Acid Dermal Fillers by Ovine Testicular Hyaluronidase

BACKGROUND Although adverse events are uncommon with hyaluronic acid (HA) fillers, the use of hyaluronidase permits the reversal of treatment complications or overcorrection. OBJECTIVE This study sought to determine an in vitro dose-response relationship between ovine testicular hyaluronidase (OTH) and three HA dermal fillers (24-mg/mL smooth gel, 20-mg/mL particulate gel, and 5.5-mg/mL particulate gel with 0.3% lidocaine). METHODS AND MATERIALS The dose response of each was measured after incubation for 30 minutes in concentrations ranging between 5 and 40 U of OTH. Timed responses for the 24-mg/mL and 20-mg/mL HA fillers were obtained after incubation with 20 U of OTH for 15 to 120 minutes. RESULTS After all dose responses and timed-interval tests, the 24-mg/mL HA smooth gel filler exhibited more resistance against in vitro enzymatic degradation to OTH than the 20- and 5.5-mg/mL HA particulate gels. CONCLUSION This resistance to degradation in vitro may be attributed to the higher HA content of the 24-mg/mL HA smooth gel, the degree of crosslinking, and the cohesive property of the gel filler. This study was funded by a grant from Allergan, Inc., Santa Barbara, CA. Derek Jones, MD, is a consultant, investigator, advisory board member, and speaker for Allergan, Inc. He received no compensation for this study. Drs. Tezel and Borrell are employed by Allergan, Inc., Santa Barbara, CA. Editorial assistance was provided by Health Learning Systems, a part of CommonHealth, Parsippany, NJ.