Sodium Deoxycholate 1% (10ml)

Deoxycholic acid is a component of human bile acid, which plays a vital role in emulsification and digestion of fat in the intestine. Rotunda and colleagues demonstrated that externally developed deoxycholic acid physically disrupts the cell membrane of adipocytes causing cell death and that relatively protein-poor tissue such as fat is more sensitive to the cytolytic effects of deoxycholic acid than relatively protein-rich tissues such as skin and muscle. Clinical efficacy and safety of deoxycholic acid have been established by multiple studies.

Deoxycholic acid injection was approved in 2015 as a first-in-class injectable drug for improving the appearance of double chin associated with submental fat.

Concentration of Substances

On reviewing literature, one realizes that multiple variable combinations of both deoxycholic acid and phosphatidylcholine have been tried. Some standard combinations are as follows.

Lipostabil contains phosphatidylcholine (50mg/mL) together with deoxycholic acid, sodium hydroxide, sodium chloride, α-tocopherol, benzyl alcohol, and ethanol.

Mechanism of Action

Following injection of lipolytic solution, the adipocyte cell wall is destroyed, resulting in the cascade of inflammatory necrosis of cell and reduction in the size of adipocytes. Inflammatory cascade also results in fibroblast migration and stimulation, resulting in buildup of more collagen

Persistent submental fat: Clinically manifests as moderate-to-severe convexity or fullness inferior to jawline, also termed as a double chin appearance. Till date, the use of injection lipolysis is approved by the USFDA only in the reduction of persistent submental fat.

Other face and neck fat pads: Facial fats like cheek, chin and jaw fat pads are injected by few physicians as off-label indications. The results of these indications are variable and techniques are not standardized as that of submental fat injection.

A few cases of injection of fat busters in lipoma and male breasts are also reported.

As the most published data exist on double chin fat reduction, we have explained the detailed technique for it in the following sections.

Contraindications: No Absolute Contraindications exist for procedure. It can be avoided if there is infection at the site of injection entry. It should not be done in patients not willing to accept the downtime of the procedure and having unrealistic expectations.

Deoxycholic acid is injected into the submental fat with the help of a 1-mL tuberculin syringe and thin needle (usually 30 G and 13mm).

The following steps are carried out:

• After consent and accurate photography, the injection area is marked as explained previously.
• Complete aseptic precautions are followed while injecting. In our opinion, topical anaesthesia does not play any role in reducing the discomfort of injection as fat is placed deep; however, for sensitive patients, it may be used.
• Typically, 3–5mL of deoxycholic acid is injected per session divided in multiple pricks, and dose per injection prick is close to 0.2–0.3mL.
• It is wise to pinch the submental fat with a nondominant hand so as to ensure the correct plane of injection. The depth of the prick has to be between 6 and 10mm as the fat is deep seated.
• Typically, three to five sessions are required with an interval of 4 weeks between two sessions. In our experience, the duration between two sessions can be increased to 8 weeks so as to reduce the number of sessions.
• Topical antibiotics are applied after injections.
• Patients shall experience some discomfort and pain after injection, lasting from 2 days to 2 weeks followed by reduction of fat.

Patients can experience mild swelling, discomfort, and pain as an indicator of inflammation for the duration varying from 2 days to 2 weeks post injection.

Patients can be aligned for the same. Cold compresses can be effectively used to alleviate discomfort. Oral anti-inflammatory medicines are rarely used.

Patients are instructed not to massage the treated area for the next 48h.

Usually, the patients can be followed up after 4 weeks to assess the results and also to plan further sessions as per their requirement..

Discomfort, pain, and swelling: These are most common and shall subside with time. Swelling and pain after only deoxycholic acid injection may last up to 10–14 days, whereas the discomfort after injection of the combination of deoxycholic acid and phosphatidylcholine usually lasts for up to less than a week.

Bruise/ecchymosis: These are due to injury to local blood vessels, are very localized, and disappear in a few days.

Marginal mandibular nerve injury: This is due to injecting a lot of deoxycholic acid close to the nerve. Clinically, it may result in asymmetrical smile. It can be avoided with correct injection technique in most of the individuals.

Skin ulceration: Superficial injection may result in ulceration, hence should be avoided.

Rarely dysphagia can occur.

Summary

Deoxycholic acid is a first-in-class injectable drug for the reduction of submental fat and represents a minimally invasive, customizable alternative to liposuction and surgery for the patients with moderate-to-severe submental fullness.

Phosphatidylcholine combination probably helps in the transportation of free fatty acids after breakdown. Injection lipolysis is extremely effective and safe in the treatment of submental fat, and usually without the need for adjunctive treatments to address skin laxity.