Safety and Efficacy of Deoxycholic Acid for Reduction of Upper Inner Thigh Fat

January 2022 | Volume 21 | Issue 1 | 66 | Copyright © January 2022


Published online December 21, 2021

Joyce T. Yuan MD, Faiza Shafiq MBBS, Arisa E. Ortiz MD

University of California San Diego, San Diego, CA

Abstract
Background: Deoxycholic acid is an FDA-approved injectable for treatment of excess submental fat.
Objective: Study purpose was to evaluate the safety and efficacy of deoxycholic acid for reduction of upper inner thigh fat.
Methods and Materials: Fifteen subjects received 2–4 treatment sessions of deoxycholic acid 10 mg/mL injected into upper inner thigh fat. Subjects were followed to 12 weeks after last treatment. Adverse events were monitored. Efficacy measures were changes in thigh circumference, upper inner thigh skin fold thickness, and “thigh gap;” and percent accuracy by two independent blinded physicians in identifying post-treatment photographs. Patient satisfaction was assessed with questionnaires.
Results: There were no serious adverse events. All patients experienced expected side effects. At 12-week follow-up, decreases in thigh circumference (average change -2.2 cm) and upper inner thigh skin fold thickness (average change -8.8 mm) were observed. Average increase in “thigh gap” was 1.6 cm. Two blinded investigators correctly identified the post-treatment photograph for 83% of patients. On Subject Self-Rating Scale (6-point scale), there was average +3.0 improvement; 86% of patients were satisfied with treatment.
Conclusion: Deoxycholic acid injection was safe and effective for reduction of upper inner thigh fat in this Phase I study.

J Drugs Dermatol. 2022;21(1):66-70. doi:10.36849/JDD.5919

INTRODUCTION

Unwanted upper inner thigh fat is a common aesthetic complaint. Current treatment options include liposuction, cryolipolysis (CoolSculpting, Allergan, Irvine, CA), and non-invasive energy-based devices for fat reduction; these are associated with respective safety and efficacy profiles. Liposuction is an invasive procedure, with rare but serious risks including nerve damage, bleeding, fat embolization, and complications from anesthesia.1 Cryolipolysis is non-invasive, with adverse effects including up to two weeks of pain and aching; temporary redness, swelling, or bruising; and very rarely, paradoxical adipose hyperplasia.2

Deoxycholic acid (Kybella, Allergan, Irvine, CA) is an FDA-approved injectable for treatment of submental fat. It is not currently FDA-approved for upper inner thigh fat treatment. Phosphatidylcholine, a fat-emulsifying soybean lecithin, was initially developed as an injectable drug for adipocytolysis; deoxycholic acid, a secondary bile acid, was added to increase solubility.3 Later studies suggested deoxycholic acid, rather than phosphatidylcholine, as the major active compound.3-5 Deoxycholic acid is thought to cause direct adipocyte cell membrane damage by inducing an inflammatory reaction.3,4,6-8

Deoxycholic acid for reduction of submental fat has been extensively studied; several double-blind, multi-center, randomized clinical trials, enrolling around 1800 patients, demonstrated safety and efficacy.3,9-12 In phase 3 trials, both 1 mg/cm2 and 2 mg/cm2 doses were safe and well-tolerated, and more effective than placebo in reducing submental fat.9 Subjects were treated with a maximum of four treatment sessions, spaced approximately 28 days apart, with follow-up at 12 weeks after the last treatment. Efficacy measures included caliper measurements, a subject self-rating scale (0 to 6), a clinician-reported submental fat rating scale, and patient-reported submental fat rating scale.9 At 12-week follow-up, patient satisfaction with appearance was 65.4% with deoxycholic acid 2 mg/cm2, compared with 60.8% with deoxycholic acid 1 mg/cm2, and 29.0% with placebo.9 Common side effects were mild-to-moderate pain, swelling, ecchymosis, numbness, bleeding, and induration including fibrosis.3,9-12 Temporary marginal mandibular nerve injury, resulting in asymmetric smile, occurred in 2.1% of patients treated with deoxycholic acid.9 There were no clinically significant changes in laboratory values or vital signs. No treatment-associated deaths were reported.3,9-12

Phosphatidylcholine with deoxycholic acid (PC/DC) has been studied as an agent for injection lipolysis.6-8 A PC/DC formulation, Lipostabil, has been advertised abroad for several decades.13 However, high-quality clinical trials are lacking,