Endoscopic Ultrasound Guided Gastric Botulinum Toxin Injections Versus Glucagon Like Peptide 1 Receptor Agonist in Weight Loss

Introduction

Obesity is an important public health concern. Although most pharmacologic therapies have targeted the central nervous system, surgical treatments induce satiation by decreasing the size of the gastric reservoir and inducing maldigestion or malabsorption.

Surgery is effective but invasive and expensive, and some obese persons are not good surgical candidates. Promising pharmacologic and endoscopic approaches to obesity include treatments that affect gastric volume, gastric emptying, gastric compliance, and satiation.

In rats, botulinum toxin A (BTA) injected subserosally into the antrum resulted insignificant decreases in caloric intake and body weight when compared to control and injected rats. Subsequent open-label human studies and three small randomized trials have reported conflicting results, with some studies finding little or no body weight loss after gastric BTA injection and one randomized controlled trial showing statistically significant decreases in gastric emptying and body weight . These trials differed in BTA dose (100 to 300 U in Botox formulation equivalents) and location of injections (antrum alone vs. antrum, body, and cardia). Depth of injection in the gastric wall was largely unknown in these studies, as endoscopic ultrasound (EUS) was not used to guide injection into the muscularis propria or subserosal layers.

In a study by Topazian. (2008), mean body weight reduction was similar in subjects receiving 100 or 300 U BTA (5.0 vs. 4.8 kg). There was a no significant trend toward loss of more body weight in the three subjects who developed decreased gastric emptying after receiving 300 U BTA. Also EUS guidance would help to assure injection of BTA in the gastric muscularis propria and subserosal layers of the gastric wall.