Injection lipolysis
The earliest version of non-invasive fat dissolution was ‘mesotherapy’, which is a general term that describes percutaneous injection of a medication or other agent into the mesoderm. A variety of applications have been described, the most popular of which has been reduction of subcutaneous fat by dissolution.72 The concept dates back to 1952 and involves injection of phosphatidylcholine, deoxycholate, and/or other agents that are purported to dissolve fat. Widespread marketing and patient desire to avoid anesthesia have allowed mesotherapy and its variants to gain popularity because of their “non-invasive” nature. However, large-scale studies are not available for evaluation. Parket al.73 showed no discernible difference in the treatment in lower extremities with mesotherapy by measurement or CT scan evaluation.
“Lipodissolve” is considered by some, but not all, practitioners to be a variant of mesotherapy. It is the injection of a standardized solution into the subcutaneous fat, rather than the mesoderm. The use of these products in the United States is controversial and not supported by the US Food and Drug Administration (FDA). Warnings from the FDA caution providers against its unproven use and false marketing claim.74 Several studies on safety and efficacy are available for review. Common side effects reported include hyperpigmentation and persistent pain, and 12% of patients had cosmetic outcomes that were less favorable than expected.75 Due to lack of scientific data and adequate studies and outcome results, the use of mesotherapy or its variants is not currently recommended, unless performed in conjunction with a clinical trial.
The most promising of injectable lipolytic agents is Kybella (Allergan Inc., Irvine, CA) or deoxycholic acid, which is a cytolytic agent that physically destroys the adipocyte cell membrane when injected. Kybella has gained FDA approval for improvement of moderate to severe convexity or fullness associated with submental fat in adults. Safety and efficacy of use of Kybella outside of the submental region has not been established and is not recommended. The cytolytic effect of deoxycholic acid is powerful, and injection should only be performed by experienced physicians with proper training in injection technique. Knowledge of submental anatomy is essential to avoid injury to neuromuscular, vascular, lymphatic, and salivary structures. Adequate preplatysmal fat is assessed by skin pinch while the patient contracts the platysma muscle, and injection is administered in a grid pattern with 1-cm intervals between sites. Injection should be administered midway into the preplatysmal fat layer, at least 1–1.5 cm below the inferior border of the mandible; special attention should be paid to anatomical distortion due to prior surgical or aesthetic procedures. Large randomized placebo-controlled clinical trials have supported the safety and efficacy of Kybella in submental contouring by means of clinical observation and magnetic resonance imaging (MRI) evaluation.76,77 Common adverse events include injection site reactions, such as pain, swelling, induration, bruising, numbness, and erythema. Less commonly seen adverse events are marginal mandibular neuropraxia, skin ulceration, and dysphagia. Complications are related to injecting in proximity to vulnerable anatomic structures, so injection technique is of utmost importance.