Oral Gentamicin Sulphate Nanoemulsion for Systemic Indication: Formulation and Evaluation

Aim: To achieve systemic availability of an oral dosage form of gentamicin sulfate (GS), typically impermeable via the gastrointestinal tract.

Study Design: Formulation and physical characterization of GS nanoemulsion. Stability studies and ex vivo bioavailability evaluation of the emulsion.

Place and Duration of Study: Department of Pharmaceutics and Pharmaceutical Technology, Faculty of Pharmaceutical Sciences, Nnamdi Azikiwe University Awka, Anambra State, Nigeria; between January 2021 and May 2023.

Methodology: Pre-formulation experiments were conducted with adjuvants for use for the formulation. Using a homogenizer, an aquaphilic GS nanoemulsion was prepared with the adjuvants, including polysorbate 80 and span 80, as permeation enhancers. The emulsion was evaluated for its globule size and polydispersity index, and real-time physical stability parameters using pH and relative viscosity. The bioavailability of gentamicin sulphate was assessed as ex vivo anti-E. coli activity after oral administration of the emulsion to Wister rats and a confirmatory test was done using gas chromatograph-flame ionization detection (GC-FID) analysis.

Results: The emulsion had an average globule size of 66.55 nm, and is monodispersed with a polydispersity index of 0.45. The pH and viscosity values measured for 60 days ranged from 6.60±0.00 to 6.80±0.00 and .03±0.00 to .03±0.01 respectively (P = .05). The ex vivo antibacterial activity of the GS emulsion was significant at 3.00±0.00 mm 1 –hr post-administration to the Wistar rats, indicating systemic availability of the antibiotic. The GC-FID analysis confirmed the presence of the drug in the serum.

Conclusion: The bioavailability of oral GS is achievable through simple specialized formulations containing adjuvants which contributes to an improved gastrointestinal permeability of the drug.