Breathing via the gut – 6 week non-clinical in-vivo study to assess safety and efficacy of an enteral CO2 absorber for the treatment of hypercapnia

Introduction : We have designed a concept to use the gut as gas exchange membrane for CO 2 elimination. For this purpose, we developed a suspension containing CO 2 absorbing microparticles. In this study, we evaluated safety and efficacy in a large animal model for a period of 6 weeks. Material & Methods : Enteral CO 2 absorber-particles in the form of microspherules, consisting of calcium hydroxide and polyethylene were prepared. These microspherules were suspended in 1.4 wt% guar gum solution. Domestic pigs received either the microspherule solution or tap water with their chow three times per day for a period of 6 weeks. Animals were checked for clinical findings (behavior, respiratory rate, feces frequency and consistency, signs of abdominal discomfort) daily. Hematology, clinical chemistry and body weight were assessed and feces collected for analysis of CO 2 uptake by the microspherules weekly. After 6 weeks, a complete necropsy was performed, and samples were taken for histology. Results : Animals did not exhibit clinical findings during the experiment. Feces frequency and consistency did not differ between the intervention and control groups. Hematology and clinical chemistry remained within species specific ranges. Body weight increases did not differ between groups. Necropsies did not reveal any test-item related finding. Microspherules eliminated 8.2 L±0.2 L CO 2 per 100 g. CO 2 uptake remained constant during the experiment’s duration.