In vitro and in vivo Evaluation of Succinic Acid-Substituted Mesoporous Silica for Ammonia Adsorption: Potential Application in the Management of Hepatic Encephalopathy.

PURPOSE

Hepatic encephalopathy (HE) is a critical situation in which liver failure affects brain function. HE could result in a state of coma and death. The liver is the main organ for ammonium ion (NH ) metabolism. Hence, acute and/or chronic liver failure could lead to hyperammonemia. NH is the most suspected neurotoxic agent in HE. Thus, finding new therapeutic options to decrease plasma and brain NH levels has a significant clinical value. Mesoporous silica (MS) particles have revolutionized many aspects of pharmaceutical sciences, including drug delivery systems. Moreover, recently, MS has been applied as agents for the detoxification of chemicals (eg, drugs and poisons).

METHODS

First, MS particles containing amine groups (MS-NH) were synthesized in co-condensation processes. Then, the structure was modified by succinic anhydride to have MS-SA. The MS-SA was characterized (FT-IR, XRD, X-ray photoelectron spectroscopy (XPS), DLS-Zeta FESEM-EDX, and HRTEM). Then, the potential of MS-NH and MS-SA particles in adsorption of NH was investigated in vitro and in vivo. MS-NH and MS-SA were incubated with increasing concentrations (0.1-10 mM) of NH , and the scavenging capacity of the investigated particles was evaluated. On the other hand, different doses (1 and 5 mg/kg per day) of nanoparticles were administered to a hyperammonemia animal model.

RESULTS

It was figured out that both MS-NH and MS-SA significantly scavenged NH in the in vitro model. However, the NH scavenging capability of MS-SA was more significant. Administration of MS-NH and MS-SA also considerably decreased the level of ammonium in plasma and brain and improved cognitive and locomotor activity in hyperammonemic animals. The effects of MS-SA were more significant than MS-NH in the HE animal model.

CONCLUSION

Collectively, our data suggest that MS particles, especially succinic acid-functionalized MS, could act as special ancillary treatment in HE as a critical clinical complication.