Effects of intramural administration of Botulinum Toxin A on gastric emptyng and eating capacity in obese patients

Background: Intraparietal gastric administration of Botulinum Toxin A has been studied in open trials to induce satiety and increase weight loss of obese patients with contradictory results. In previous studies only the antrum was the target for Botulinum Toxin A, whereas the fundus, which exerts important activity on gastric accommodation, was excluded. In this study we report the effects of injection into both gastric regions on solid gastric capacity and emptying of the stomach. Materials and methods: In this study we extended our previous investigations to include 30 obese patients who received Botulinum Toxin A (120 U into the antrum and 80 U into the fundus) or saline by intraparietal endoscopic injection. The two groups were homogeneous for age, gender, body weight and body mass index. Body weight and body mass index, solid gastric emptying (T(1/2) and T(lag) at the octanoic acid breath test) and maximal gastric capacity for solids (kcal) were determined before injection and 2 months later. The results were expressed as mean values (S.E.M.). t-Test or Wilcoxon test was used for statistical analysis, p<0.05 being considered significant. Results: Both treatments induced a significant reduction of body weight and body mass index but Botulinum Toxin A exerted a significantly greater effect (body weight -11.8+/-0.9 kg vs. -5.5+/-1.1 kg, p<0.0002; body mass index -4.1+/-0.2 vs. -2.2+/-0.4, p<0.001). The maximal gastric capacity for solids was also reduced by both Botulinum Toxin A and placebo, the former being significantly more effective (679+/-114 kcal vs. 237+/-94 kcal, p<0.008). Botulinum Toxin A also significantly increased T(1/2) from 83.4+/-3.9 to 101.6+/-9.9 min, p<0.03) but T(lag) was unchanged. Placebo had no effect on either of these parameters. Conclusions: Our results demonstrated that Botulinum Toxin A makes weight loss easier in obese patients. It acts by increasing the solid gastric emptying time and reducing the solid eating capacity of the stomach.