Giardiasis is a parasitism produced by the protozoa Giardia intestinalis that lives as trophozoite in the small intestine (mainly in the duodenum) attached to the intestinal villus by means of billed discs. The first line treatment is metronidazole, a drug with high bioavailability, which is why to obtain therapeutic concentrations in duodenum, it is necessary to administer high doses of drug to patients with the consequent occurrence of side effects. It is necessary to developed new therapeutical approaches to achieve a local delivery of the drug. In this sense, we have developed gated mesoporous silica microparticles loaded with metronidazole and with a molecular gate pH dependent. In vitro assays demonstrated that the metronidazole release is practically insignificant at acidic pHs, but in duodenum conditions, the metronidazole delivery from the microparticles is effective enough to produce an important parasite destruction. In vivo assays indicate that this microparticulate system allows to increase the concentration of the drug in duodenum and reduce the concentration in plasma avoiding systemic effects. This system could be useful for other intestinal local treatments in order to reduce doses and increase drug availability in target tissues.

中文翻译：

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pH依赖的分子门介孔微粒的肠道贾第鞭毛虫的生物控制。

贾第鞭毛虫病是由原虫贾第鞭毛虫肠道产生的寄生虫它通过有价盘在小肠（主要在十二指肠）中以滋养体的形式附着在小肠绒毛上。一线治疗是甲硝唑，它是一种具有高生物利用度的药物，这就是为什么要在十二指肠中获得治疗浓度的原因，有必要向患者服用高剂量的药物，从而导致副作用。有必要开发新的治疗方法以实现药物的局部递送。从这个意义上讲，我们已经开发出装有甲硝唑且具有门pH依赖性分子的门控介孔二氧化硅微粒。体外试验表明，甲硝唑在酸性pH下的释放实际上微不足道，但在十二指肠条件下，从微粒中递送甲硝唑足以产生重要的寄生虫破坏。体内测定表明，该微粒系统允许增加十二指肠中药物的浓度并降低血浆中的浓度，从而避免了全身性作用。该系统可用于其他肠道局部治疗，以减少剂量并增加靶组织中的药物利用率。