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Surgery and Cosmetics

James M. Spencer, MD, MS

Deoxycholate Injections for Submental Fat Melting

James M. Spencer, MD, MS

Saturday, August 01, 2015

Background

Localized fat deposits remain a common cosmetic complaint. One area where localized fat deposits are commonly seen is the submental area. Previously, liposuction was the treatment of choice for such localized deposits. Tissue-tightening radiofrequency devices can tighten the skin, but do not address the accumulation of fat. More recently, cryolipolysis has become available for localized fat deposits on the torso (coolsculpting) but there is no handpiece for this device that fits under the chin. An injectable fat melting technique is a desirable alternative as it avoids invasive surgery.

Mesotherapy is a large treatment area utilizing a wide variety of compounds injected into the skin for cosmetic enhancement. Among the many substances injected over the years, phosphatidylcholine gained popularity for a supposed ability to melt fat. The phosphatidylcholine was mixed with deoxycholate, a naturally occurring bile acid to solulabize and thus make injection possible. Recently it has become clear the fat-melting effect seen was due to the deoxycholate, not the phosphatidylcholine. This has led to a deoxycholate injectable solution obtaining FDA approval for submental fat melting.

Deoxycholate is a bile acid produced by bacteria in the gut, which helps emulsify fat and aid in digestion. When injected into the fat under the chin, it disrupts fat-cell membranes and ultimately cause cell lysis; this is therefore permanent fat removal. However, the product may also cause mild inflammation and mild fibrosis.

Procedure

The ideal concentration of deoxycholate has been found to be 10 mg/mL, administered in a series of 0.2 mL injections with a 30 g needle. The product comes with a rub-on grid that may be applied over the area to be injected in order to define the injection points - this is a series of dots, 1 cm apart, which allows for the desired amount of diffusion with a 0.2 mL injection. The important structures of the neck are marked and danger zones such as the course of the marginal mandibular nerve or the thyroid gland can be avoided. The marginal mandibular nerve can be above or below the mandible posterior to the facial artery, but once it crosses anterior to the artery, the nerve is always above the mandible. Thus, one should not inject too laterally on the neck nor too close to the mandible medially.

The area can be pre-injected with lidocaine with epinephrine to provide pain relief. Some injectors encourage the patient to wear a light compression dressing to minimize bleeding and swelling, but this is not required. The product comes in 2 mL vials and two vials are typically required to treat the submental area. The treatment is repeated in 1 month for up to six injection sessions, with most patients requiring four but some as little as two. Figures 1 and 2 demonstrate the effect of treatment with deoxycholate.

 

Deoxycholate 1

Figure 1. Front view of a patient both before and after treatment with deoxycholate in the submental region.

 

Deoxycholate 2

Figure 2. Side profile of a patient both before and after treatment with deoxycholate in the submental region.

 

Efficacy and safety in clinical trials

Four large Phase III trials are now complete showing both safety and efficacy. Results from these studies indicated that 68.2% of subjects responded to therapy versus 20.5% of placebo patients. Additionally, 79% of treated patients were satisfied with the procedure. The most commonly reported adverse events from the trials were edema/swelling, hematoma/bruising, pain, numbness, erythema, and induration. Of note, 4% developed transient paresis of the marginal mandibular nerve, as manifest with an asymmetric smile, though all cases resolved. Dysphagia may also occur in up to 2% of subjects. Careful patient selection remains the most important factor in obtaining a favorable outcome. Other causes of under-the-chin fullness, such as lymphadenopathy or platysmal banding should be identified and excluded. The ideal patient will have minimal skin laxity so that the skin will not 'hang' once the fat is dissolved. 

Future implications

The issue of off-label injection of other sites will certainly be of interest to injectors. Currently, the product is FDA approved for submental injection only, and the manufacturer has no information on off-label injection at other sites. This issue must await future studies to ascertain safety and effectiveness at off-label sites.

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