The recent approval of Kybella for the treatment of under the chin fat (submental) fat appears like it is a new treatment. And as an FDA-approved drug it is. But the concept of a fat dissolving injectable drug is really now new and has a predicate history in the world of mesotherapy and the now defunct term of Lipodissolve. The active ingredient in many compounding pharmacy (and non-FDA approved) mesotherapy solutions is deoxycholic acid…the same one that is in FDA-approved Kybella.
Kybella is a synthetic version of a naturally occurring bile salt which resides in the gallbladder, known as dexocycholic acid. Known also as deoxycholate and chemically as 3?,12?-dihydroxy-5?-cholan-24-oic acid, it is a secondary bile acid created as a metabolic by product of the intestinal bacteria. The two primary bile acids secreted by the liver are cholic acid and chenodexoycholic acid which bacteria eventually break down eventually into secondary bile acids. Deoxycholic acid is the metabolite from cholic acid.
The role that deoxycholic acid performs in the body is the breakdown (emulsification) of dietary fat so it can be absorbed in the intestine. It has a detergent-like effect on fat to break down the cell walls through solubilization of its membrane components. It is no surprise then that it is not a far leap to envision how it might work on reducing small subcutaneous fat deposits.Thus the FDA approval after numerous clinical studies for the use of Kybella for a small fat area like that under the chin. (submental fat)
The key to successful use of Kybella is patient selection. It simply is not going to be effective for large fat collections. While patients with larger and fuller necks may be drawn to an injectable therapy for an injectable treatment as opposed to surgery, they will likely be disappointed with the treatment process and the final result. Patients must also understand that this is a series of treatments that works slowly and will take several months to see the final result. It is important to compare this injectable treatment process to what can be achieved just as effectively (and perhaps better0 with a 30 minute surgical liposuction procedure.
Injection treatments take about 15 minutes to complete and are done using a marked grid pattern in the treatment area, spacing them about 1 cm apart. (the solution will diffuse from the injection site about 1 cm in all directions. Based on the treatment area size the number of injections can range from 35 to 50 and takes about 4 ml of the Kybella solution using .1cc volume per injection site. Almost always it takes more than one treatment to see the best result and could be as many as six treatments to see the maximal effect. Injection sessions should be done no closer than four to six weeks to let the maximal fat clearance effect take place.
One immediate and postoperative issue that patients need to be aware of is that significant post-injection inflammation and swelling will occur. Within minutes after the injections the treated area will feel hot and have a burning sensation. Within 48 hours the neck will have a swollen wattle that will go away in one week or less. Some injected areas that will feel numb for a few days. This is the result of how the solution works…an active breakdown and inflammatory process of the treated fat cells. Patients can use NSAIDS and topical ice for pain relief during the first day of treatment. The point is that there is a recovery phase just like surgery. It is not like Botox where they are few noticeable after injection sequelae.
Because there is some important anatomy that runs through the submental area, there are some other associated risks with Kybella injection therapy. This directly refers to the marginal mandibular nerve, the lower branch of the facial nerve that supplies movement to the depressor anguli oris muscle of the lower lip. Such injuries to the nerve have been reported although they all have resolved within several months after the injections. The best way to avoid this disturbing problem is to keep the upper border of the injection level about 1.5 cm below the inferior border of the mandible and to not inject into the jowl areas.
The cost of Kybella injections will vary by physician but a single injection session can run anywhere from $850 to $1,000. Treatment packages of four can run anywhere from $3,500 to $4,000. So patient have to consider carefully the cost of Kybella and treatment times compared to a single surgical submental liposuction procedure.
Dr. Barry Eppley
Indianapolis, Indiana