Diclofenac Sodium Stability in Simulated Gastrointestinal Fluids and the Use of MCM-41 Silica Carrier with Surface Modification to Achieve Innovative Delayed Release

Objectives: Porous silicon materials were first reported to be biocompatible in 1995. This project employed the evaluation of whether diclofenac sodium is acid labile or acid insoluble. Second, literature only reported 15% of alendronate entrapment in unmodified Mobil Composition of Matter No. 41 (MCM-41). Will functionalization of carry surface enhance drug entrapment? This project also assessed storage stability. Methods: Diclofenac sodium was subject to 0.1 N hydrochloric acid for 2 h, then in phosphate buffer pH 6.8 to determine the acid lability versus poor aqueous solubility. Entrapment parameters for unmodified MCM-41 were determined among stock concentration, driving medium, equilibration method, rate and duration. MCM-41 was then surface functionalized by tetraethylenepentamine/2-amino-2-methyl-1-propanol/ anhydrous alcohol and air dried into powder. Functionalized batch followed the same entrapment protocol as the unmodified MCM-41. Liquid chromatography and Fourier Transform Infrared were done at time zero and 3 months later. Results: Under the described conditions, the entrapment efficiency of diclofenac loaded amino-functionalized MCM-41 prepared by the immersion method was significant (p < 0.05) at 44.76% ± 3.88%, n = 3. The FT-IR spectra showed the loss of primary and protonated amino groups vibration in the 3-month-old unloaded-amino-modified MCM-41 group after being stored in room temperature. However, in the diclofenac loaded amino- modified-MCM-41 group, most amino group vibrations were still present. Conclusion: Diclofenac sodium is poorly aqueous soluble in simulating gastric fluid. Although diclofenac sodium is a cyclooxygenase-2 inhibitor, for the prolonged use in pain treatment, amino-surface-functionalization of MCM-41 may be performed to enhance drug entrapment and delay drug release due to electrostatic attraction and repulsion.