Zeoliti naturali in formulazioni farmaceutiche per uso orale: preparazione, valutazione e possibile impiego di un materiale a base di Clinoptilolite

This work investigates the possible use of clinoptilolite in formulations to be used against Helicobacter pylori, a bacterium recognized responsible for up to 70% of gastric ulcers. To survive in gastric environment the bacterium hydrolyses the urea present in the gastric juices generating ammonia which increases the pH in the stomach as, due to H+ presence, NH3 is converted to NH4+. Starting form a zeolite-rich rock, a reproducible material that maximizes clinoptilolite properties and minimizes any kind of interference was prepared. Chemical and mineralogical composition, technological properties and microbiological quality of materials were determined. Tests were performed to evaluate the resistance and the oral bioaccessibility of contaminants in simulated gastrointestinal fluids. The recommendations and procedures of European Pharmacopoeia were taken as benchmark to the largest extent possible. The material obtained was then prepared in different cation forms, and tested in-vitro against different strains (also clinical) of H. pylori, to evaluate if the clinoptilolites, due to the exchange capacity and selectivity toward ammonium, show antagonistic activity against H. pylori growth and infection. A set of antibiotics currently used in the eradication therapy of H. pylori were also considered. MIC and MBC of the antibiotics, of the forms of clinoptilolite prepared, and of combinations antibiotics+clinoptilolite were measured by using different methods.