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.
Highlights
Gentamicin sulphate is an aminoglycoside antibiotic commonly used topically in the control of severe Gram positive and Gram negative microbial infections especially in burns and wounds as well as for treating bone and soft tissue infections [1]
Microsphere-gentamicin formulated by some workers was found to be effective as potential drug carrier which could be employed for treatment of E. coli K88 infection [23]
Microsphere formulations of gentamicin using bovine serum albumin (BSA) and glutaraldehyde as a polymer matrix and cross-linker respectively were prepared by Haswani et al The products exhibited a significant increase in bioavailability which would permit a reduction in the frequency of gentamicin administration and would effectively reduce the drug’s dose related side effects [4]
Summary
Gentamicin sulphate is an aminoglycoside antibiotic commonly used topically in the control of severe Gram positive and Gram negative microbial infections especially in burns and wounds as well as for treating bone and soft tissue infections [1] It is a polarized watersoluble compound having very poor intestinal membrane permeability resulting in low oral bioavailability [2]. Efforts had been made to determine the drug’s optimal therapeutic regimens in order to increase its overall efficacy while minimizing drug toxicity These include; use of labrasol [1], liposomes [15], solidified reverse micellar drug delivery systems [16,17,18], and hydrogels [19, 20]. Microsphere formulations of gentamicin using bovine serum albumin (BSA) and glutaraldehyde as a polymer matrix and cross-linker respectively were prepared by Haswani et al The products exhibited a significant increase in bioavailability which would permit a reduction in the frequency of gentamicin administration and would effectively reduce the drug’s dose related side effects [4]
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