It's not life-threatening, but as many as 7 in 10 Americans say they're bedeviled by double chin, a condition for which the
Kybella is the first treatment the agency has approved for "moderate-to-severe fat below the chin," which is known in medical parlance as submental fat.
FOR THE RECORD
An earlier version of this post incorrectly identified deoxycholic acid as a protein. It is a metabolyte of cholesterol.
The maker of Kybella -- the Westlake Village company Kythera Biopharmaceuticals -- called submental fat "a common yet undertreated aesthetic condition" that can "result in a person feeling older and heavier."
The newly approved product is expected to become available in late summer through dermatologists, plastic surgeons and facial plastic surgeons who have been trained in the proper administration of the injectable. Kythera Biopahrmaceuticals says it will not announce the price of Kybella treatments until June when the marketing launch and the training of physicians are set to begin.
Kybella is a synthetic version of deoxycholic acid, a cholesterol by-product that is naturally produced in the body that helps with the absorption of fat. When injected into tissue, it destroys the cell membrane. When injected into subcutaneous fat such as that which accumulates under the chin, Kybella causes fat cells to dissolve.
But the FDA cautioned that Kybella was not approved for use outside of the area under the chin, where "pre-platismal fat" accumulates in pockets that are just under the skin. Its use on deeper and more concentrated pockets of fat that accumulate elsewhere, such as in the belly and buttocks, has not been found safe.
Under local anesthetic, patients would receive up to 50 injections -- placed about one centimeter apart -- in a single treatment. As many as six single treatments, administered no less than one month apart, may be necessary to achieve the desired results. But most patients were able to complete their treatment with three or four sessions, said Dr. Derek Jones, the lead investigator of the clinical trial of Kybella assessed by the FDA in its deliberations.
Unlike injectable cosmetic fillers, the effect appears to be enduring. Once the treatment has been completed, re-treatment is not expected to be necessary, the company said.
Jones, the founder of Skin Care and Laser Physicians of Beverly Hills, called deoxycholic acid "an extremely well-studied medicine" whose safety has been established in at least 20 studies. Temporary swelling and tenderness are common around the site of injections, with occasional bruising and numbness, he said. In rare instances, patients sustained temporary nerve damage that created some asymmetry when they smiled.
"We know now how to prevent that," he said, noting that the nerve disturbance resolved itself in all cases.
The FDA noted that "areas of hardness in the treatment area" were also common. The agency said that caution should also be used in patients who have had previous surgical or aesthetic treatment of the submental area.
Jones said that in the clinical trial he ran, 79% of those who received Kybella reported satisfaction with their appearance, and that "some of the results are really quite spectacular."
"We're aiming for progress, not perfection," he cautioned.
Submental fat can be the result of genetics, aging and weight gain. But the clinical trial that prompted the FDA's decision excluded people with obesity. Jones said that although Kybella has not been assessed or approved as tightener of skin, researchers were surprised to observe that "most patients had some degree of tightening, which in some cases was quite significant."
Although Kythera has not announced what it will charge for Kybella, Jones said he had been told its price would be "in line with other injectable procedures — several hundred dollars as opposed to several thousand dollars per treatment."