Oral Gentamicin Preparation Using Solidified Lipid Particulate Delivery System

Abstract

Objective: Despite the broad pharmacological activity of gentamicin against a number of bacteria, it's very inadequate oral bioavailability due to poor intestinal membrane permeability has limited its formulation into oral dosage delivery system. This work was thus aimed at formulation and evaluation of gentamicin-loaded microemulsions based on preparation of lipid matrix for sustained release delivery. Methods:Oral gentamicin suspensions were prepared by emulsification method using Tween 80 as a mobile surfactant in the lipid matrix dispersion. The resultant oral suspensions were evaluated for mean particle size and morphology using a photomicrograph, encapsulation efficiency/entrapment, EE (%), dispersibility, pH and absolute drug content. Release study as a function of inhibition zone diameter (IZD) and in vitro release study was also carried out. The in vitro release study was performed in both simulated gastric fluid (pH 1.2) and simulated intestinal fluid (pH 7.2) respectively. The release data were analyzed mathematically according to zero order, first order and Higuchi equations. Results:The prepared suspensions were cream-white in colour, easily dispersed and well homogenized. Batch D, which had least amount of excipients incorporated into the lipid matrix showed clumped irregular-shaped and less free-flowing particles. The particle size was significantly influenced by lipid matrix combination ratio in the presence of a surfactant (p<0.05). The mean particle size diameters of the samples were 15.44 mm, 10.64 mm, 4.12 mm, and 2.70 mm for batches A, B, C and D respectively. The values of EE obtained varied between 47% and 59% with Batch B exhibiting the highest value. The Higuchi model gave the best release kinetics result followed by zero order kinetics. Conclusion:Oral gentamicin prepared exhibited antibacterial properties against Klebsiella spp., Escherchia coli, Bacillus subtilis, Staphylococcus aureus, and Pseudomonas aeruginosa. The results suggest that a lipid matrix system could be useful as a sustained release oral delivery system of a poorly absorbable drug such as gentamicin.