Pore size effect on adsorption and release of metoprolol tartrate in mesoporous silica: Experimental and molecular simulation studies.

Mesoporous silica nanoparticles (MSNs) have been widely studied as drug carriers to get sustained release behaviors, however, their application in sustained release of metoprolol tartrate (MPT) is limited. The possible reason is due to MPT molecule being bulky, while normal type MSNs like MCM-41 and SBA-15 have pore sizes of only 3-6 nm. In this study, two MCF-26 type MSNs were prepared with pore size of 11 or 15 nm, and used to conduct MPT release in comparison with MCM-41 and SBA-15. Both molecular simulation and MPT release experiments were performed to identify the pore size effect on adsorption and diffusion (release) of MPT in these MSNs. Finally, a kind of pH-sensitive MPT drug delivery system was obtained by coating the chosen MCF-26@MPT with an enteric polymer, which might find promising application in treating morning hypertension attack by orally administrating the drug delivery system before bedtime.