Endoscopic Ultrasound-Guided Gastric Botulinum Toxin Injections in Obese Subjects: A Pilot Study

Background Gastric injections of botulinum toxin A (BTA) may induce changes in gastric emptying and body weight, but results vary. BTA dose and depth of injection may affect efficacy. This study assessed changes in gastric emptying, satiation, symptoms, and body weight after endoscopic ultrasound (EUS)-guided injection of 100 or 300 U BTA into gastric antral muscularis propria of obese subjects. Methods Open label study of ten healthy, obese adults (age = 29–49 years, body mass index = 31–54 kg/m²) who received 100 U (n = 4) or 300 U (n = 6) BTA and were followed for 16 weeks. Measures included gastric emptying of solids (by scintigraphy), satiation (by maximum tolerated volume [MTV] during nutrient drink test), gastrointestinal symptoms (by the Gastrointestinal Symptom Rating Scale), caloric intake (by food frequency questionnaire), and body weight. Results For the entire cohort, MTV decreased from 1,380 cc (range: 474–2,014) at baseline to 620 cc (range: 256–1,180) 2 weeks after BTA injection; decreases were statistically significant in the subjects receiving 300 U BTA (p = 0.03). Average body weight loss was 4.9 (±6.3) kg after 16 weeks. Gastric emptying T_1/2 was prolonged in the 300 U BTA group, but not significantly different from baseline (p = 0.17). BTA injections were well tolerated without significant adverse effects. Conclusion EUS-guided injection of BTA into gastric muscularis propria can be performed safely with minimal adverse effects. A dose of 300 U BTA significantly enhances satiation, is associated with weight loss, and may slow gastric emptying. Further study of higher dose BTA in obese subjects is warranted.