Porous Silica as Drug Carrier for Controlled Delivery of Sulfasalazine: The Effect of Alginate-N, O-Carboxymethyl Chitosan Gel Coating and Amine Functionalization.

The necessity of colon-specific drug delivery systems has been well recognized. Porous silica (PSi) coated with a pH-sensitive, biocompatible, and biodegradable polymer can be useful in colon delivery. In this study, porous silica was synthesized and sulfasalazine was loaded into it to investigate the release rate in a simulated intestinal media. The media was kept at 37 °C and pH 6.8 and 7.4, and subjected to continuous ultrasonic waves to simulate body fluid flow. Aqueous alginate and N, O-Carboxymethyl chitosan (NOCC) solutions, with a distinct composition (3% W/V) in different ratios, were prepared and coated on pressed porous silica disks. Porous silica (PSi) was also functionalized by aminopropyltrimethoxysilane grafting and was studied as a potential carrier for the controlled drug release of sulfasalazine. The release was studied in simulated gastric and intestinal media and results show that no burst release occurred in both coated and functionalized samples and the swelling degree of coats at basic and neutral media decreased by the presence of alginate in the network. It is concluded that the coat with a 50:50 ratio can release the colon drugs in 24 h at a suitable rate. It is also envisioned that functionalization was a factor boosting drug uptake, however, the release rate was lower in the functionalized samples. This study opens the gates to new ideas for the potential safe and localized delivery of sulfasalazine.