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HOLLYWOOD, FL. – Pick the right patient, set realistic expectations, and use a cautious technique for the best result with deoxycholic acid, advised Joe Niamtu, DMD, a cosmetic facial surgeon in private practice in Midlothian, Va.
Speaking at the annual meeting of the American Academy of Cosmetic Surgery, Dr. Niamtu shared tips and techniques for best results using deoxycholic acid (Kybella) injection for reduction of submental fat, based on several months of real world use since it was approved in 2015.
Dr. Joe Niamtu
Deoxycholic acid, a bile acid, causes breakdown of adipocytes when injected into fatty tissue. Since the resulting dissolution of fat cells is permanent, once the desired aesthetic effect is achieved, retreatment should not be needed, he said.
Currently, deoxycholic acid injection is only approved for the treatment of submental fat. Dr. Niamtu reviewed results of the pivotal phase III clinical trials for this indication, which characterized 68.2% of those receiving deoxycholic acid as treatment responders, compared with 20.5% of patients receiving placebo injections. Response was assessed by validated physician and patient assessment measures.
In clinical trials, the most common side effects were edema, hematoma, and pain, as well as numbness, erythema, and induration.
Whether it makes sense for an individual practice to offer deoxycholic acid injections “depends on the flavor of your practice,” Dr. Niamtu said. “I have a surgical practice, and my patients expect a big bang,” so only a limited number of his patients would be attracted to this procedure. By contrast, in a minimally invasive practice, this procedure might be more popular.
Overall, deoxycholic acid is an attractive option for patients who wish to avoid surgical procedures but still are seeking modest improvement in submental fat, he said. “It all depends what kind of practice you have, what kind of patients you attract, what their expectations are.”
The components of a youthful and fit-appearing neckline include a distinct mandibular border and subhyoid depression, a visible thyroid cartilage bulge, a visible anterior sternocleidomastoid line, and the cervicomental angle.
“There’s one thing about youth, and it’s that nice, defined cervicomental angle,” said Dr. Niamtu. “It’s important to understand what a youthful neck is, because that’s your endpoint.” When a double chin” appears, that angle droops and a crisp profile is lost.
Appropriate candidates for deoxycholic injection are “young people that have isolated fat deposits without skin excess,” said Dr. Niamtu. “If you inject Kybella into somebody who has a lot of extra skin, and they get a bad result, this stuff can come back to haunt you,” he said, recommending not to “sugar-coat predicted results and recovery.”
“When you are dealing with fat…there are some things you have to monitor,” he pointed out. He recommended taking very careful before and after pictures, and also weighing patients and calculating body mass index at each session. He also recommended taking pictures while the patient is smiling and puckering, to identify any preexisting paresis or asymmetry.
When injecting deoxycholic acid, the target is the preplatysmal fat of the submental triangle. “You’ve got to know where to put this stuff. The marginal mandibular nerve is vulnerable,” Dr. Niamtu observed. It can be tempting to treat the jowl, he said, but it’s important to give the nerve a wide margin, especially at a point about 2 cm lateral to the oral commissure, because that’s where the marginal mandibular nerve’s course becomes quite superficial.
“When you’re anterior to the mandibular notch, that nerve runs close to the mandibular border,” he said, noting that a number of mandibular nerve palsies were caused during the trials of deoxycholic acid. The resulting paresis gives an asymmetric smile, with less depression of the lower lip on the affected side since the depressor anguli oris and depressor labii are affected. In clinical trials, all episodes of paresis resolved spontaneously after a mean of 44 days.
To identify the targeted fat tissue, the operator can pinch the submental fat, or have the patient clench his or her teeth or tense the platysma. Though some apply topical anesthesia before deoxycholic acid injection, Dr. Niamtu, who uses a 32 gauge needle, does not. He prefers to use 2% lidocaine with epinephrine once the deoxycholic acid is going in and starts to burn, in order to avoid obscuring the fat target while planning the injection, and also to minimize any possibility of diluting the deoxycholic acid.
The product comes a wettable template that transfers a temporary tattoo of injection sites to the submental triangle, with 1 cm spacing between the dots to indicate where to inject. Each site receives 0.2 mL of deoxycholic acid. The mandibular border is marked, and another line is drawn about a finger breadth below the mandibular border. This second line forms the outer bound of the injection area. “That’s our no-fly zone. We don’t want to inject there. That’s where the marginal mandibular nerve lives,” said Dr. Niamtu.