Permanent Soft-Tissue Filler Hydrogel is Safe and Effective
By Nancy A. Melville
Medscape Medical News
October 6, 2009 (Phoenix, Arizona) — Hydrogel (Aquamid, Contura), a permanent soft-tissue filler, demonstrates a 12-month safety and efficacy profile in the treatment of nasolabial folds that is similar to the popular hyaluronic acid filler Restylane (Allergan), according to a study presented here at the American Society for Dermatologic Surgery 2009 Annual Meeting.
Hydrogel is an injectable filler composed of 97.5% sterile water and 2.5% polyacrylamide, and since being introduced in 2001, the filler has been approved for use in 40 countries. It remains an investigational agent in the United States.
The product is homogenous and nonbiodegradable, according to Rhoda Narins, MD, lead author of the study and clinical professor at New York University Medical Center in New York City.
"It is hydrophilic and allows for a continuous exchange between the hydrogel and surrounding tissue," she said. "It becomes fully integrated in the tissue in a fine fibrous network and does not migrate from the injection site."
In the randomized multicenter study involving 315 patients, 210 subjects were treated with hydrogel injections and 105 were treated with Restylane. Two touch-up treatments were allowed, for a total of 3 treatments maximum, and primary effectiveness was judged by the change from baseline to 6 months, according to the Wrinkle Assessment Scale (WAS).
The researchers also evaluated the safety of hydrogel at 12 months after treatment. At 6-month follow-up, hydrogel was shown to be as effective as Restylane, offering a mean improvement in WAS score of 1.8, which is more than 3 times the maximum predefined clinically irrelevant difference of 0.5 WAS points.
The correction with hydrogel continued through 12 months without appearing to subside, Dr. Narins noted.
"The interesting thing was that at the end of the 12 months, a lot of the substance was still left and the results were in fact still as good as they were at the optimal treatment," she said. "It's clear that patients maintain this [benefit] for long periods of time."
Adverse events through 12 months were reported to be mild and similar to those that are common with Restylane, Dr. Narins said. "The most common events were injection-related and included bruising, swelling, redness, and the kinds of events you would see with most other fillers."
One patient receiving hydrogel treatments developed an infection believed to be related to the treatment; however, the infection resolved in 24 days. As with other injectable fillers, infections could be related to biofilms or other problems, Dr. Narins said. "Physicians need to use a sterile injection technique and make sure that patients adhere to post-treatment instructions," she added.
About 25% of patients in the hydrogel group had darker skin, and Dr. Narins reported that the same efficacy and safety profile was seen in both dark- and lighter-skinned patients, with no pigmentation changes.
To accumulate longer-term data, a 24-month trial is continuing, and the most recent findings will support Contura's PMA application for hydrogel with the US Food and Drug Administration.
Dr. Narins said that one of the biggest hurdles hydrogel faces in the American approval process is a stigma related to permanent fillers in general. "The biggest barrier to entry in the [American] market is that people are simply afraid of permanent fillers."
Vivek Iyengar, MD, comoderator for the session and associate director of dermasurgery at the University of Chicago in Illinois, agreed that as a permanent filler, hydrogel faces greater concerns that only longer-term studies will adequately address.
"This study was just a year, and while it did show [hydrogel] to be comparable in efficacy to a filler like Restylane, the more important proof will be its long-term safety," he said.
The researchers received funding for the study from Contura. Dr. Narins is a consultant and investigator for Contura. Dr. Iyengar disclosed no relevant financial relationships.
American Society for Dermatologic Surgery (ASDS) 2009 Annual Meeting: Abstract CS255. Presented October 2, 2009.
