Modified diatom-based ocular suspension for sustained diclofenac sodium delivery: a novel drug carrier approach

Ophthalmic drugs typically last only around 15 minutes due to rapid elimination from tear flow, with only about 2% absorption, while the rest may enter the nasal mucosa, potentially causing systemic side effects. Diatoms, with properties like unique structure, abundance, low cost, heat resistance, non-toxicity, and easy access, present a promising solution for sustained drug delivery. This study aimed to prepare and evaluate an ocular suspension of diclofenac sodium loaded onto modified diatoms.

Diatoms were modified with aluminum sulfate solution, followed by loading of diclofenac sodium. Characteristics of diatoms before and after modification-particle size, surface charge, and drug loading-were analyzed using electron microscopy, FTIR (Fourier Transform Infrared Spectroscopy), XRD (X-ray Diffraction), and elemental mapping. BET (Brunauer-Emmett-Teller (Surface Area Analysis) testing provided adsorption data, while DSC (Differential Scanning Calorimetry) assessed thermal properties. An in vitro release study using a dialysis bag in artificial tear fluid examined drug release over 8 hours. Drug content was determined by spectrophotometry, and cytotoxicity on MDA-MB-231 and HEP-G2 cell lines was evaluated at different diatom concentrations.

SEM (Scanning Electron Microscopy) imaging showed no topographic changes post-modification. BET and XRD analyses confirmed drug loading and structural stability, while FTIR indicated involvement of carboxylate groups. TGA and DSC showed stable thermal properties. Elemental mapping confirmed increased surface elements and high drug loading. Modified diatoms showed sustained drug release and no significant cytotoxicity differences.

Modified diatoms demonstrated higher drug loading and sustained release, indicating their potential for safe and effective ocular drug delivery. Further studies are recommended to confirm these findings.