Bis(trimethoxysilylpropyl)amine and tetraethoxysilane derived gels as effective controlled release carriers for water-soluble drugs of small molecules

The controlled release of sodium salicylate (SS) from the gels derived from bis(trimethoxysilylpropyl)amine (TSPA) or the mixture of TSPA with tetraethoxysilane (TEOS) was investigated. The experimental results suggest that the release of SS can be easily controlled by adjusting the ratio between TSPA and TEOS. Increasing the ratio between TSPA and TEOS lowers the surface area and pore volume of the gels, while enhances the interactions between the drug and the gel matrix. Therefore, reduces the release rate of the drug effectively. The overall release process is found to be diffusion controlled, and the release behavior can be well explained by considering the effects of the textual properties of the gels and the interactions between the drug and the gel matrix. TSPA is found to be a very convenient and effective precursor for the preparation of gels for controlled release of both hydrophilic and hydrophobic drugs, especially water-soluble drugs of small molecules.