Preparation of aminoglycoside-loaded chitosan nanoparticles using dextran sulphate as a counterion

Authors: Lu, Enxian1; Franzblau, Scott2; Onyuksel, Hayat1; Popescu, Carmen3

Source: Journal of Microencapsulation, Volume 26, Number 4, June 2009 , pp. 346-354(9)

Publisher: Informa Healthcare

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Abstract:

Purpose. To prepare aminoglycoside (AG) (streptomycin, gentamicin and tobramycin) loaded chitosan nanoparticles with high drug incorporation efficiency and test the in vivo oral efficacy of streptomycin (SM) loaded chitosan nanoparticles in a Mycobacterium tuberculosis (TB) chronic infection mouse model. Method. Dextran sulphate (a polyanion) was used to shield the positive charge of AG and increase the drug incorporation in the chitosan nanoparticle. By varying the concentration of each component, the formulation of SM-loaded chitosan nanoparticle was optimized by monitoring the drug incorporation efficacy and particle size. The mechanism of the nanoparticle formation was suggested and the preparation method was applied to two other aminoglycosides (AG): gentamicin (GM) and tobramycin (TM). The resulting nanoparticles were characterized by particle diameter, drug incorporation efficacy, drug loading efficacy and zeta potential. The in vitro drug release from these nanoparticles was carried out in pH 1.2 and pH 7.4 buffer. Preliminary in vivo oral efficacy studies of SM-loaded chitosan nanoparticles was performed in a Mycobacterium tuberculosis (TB) chronic infection mouse model. Results. The optimal concentration of streptomycin (SM)/dextran sulphate/chitosan/tripolyphosphate (TPP) for SM nanoparticles preparation was 2/1.2/2/0.8 mg mL-1. Through calculation, the optimal concentrations of dextran sulphate are 2.5 mg mL-1 and 2.4 mg mL-1 for 2 mg mL-1 gentamicin and tobramycin, respectively (Table 1). The resulting AG chitosan nanoparticles had a high drug incorporation efficacy with particle sizes in the nanometre range. The in vitro drug release studies showed that more than 60% drug is retained inside the nanoparticles in pH 1.2 buffer after 6 h. The preliminary in vivo results indicated that oral SM chitosan nanoparticles induced one log 10 reduction (p < 0.01) in growth of the bacilli and were as effective as subcutaneously injected aqueous SM solution at the same concentration (100 mg kg-1). Table 1. The optimal amount of dextran sulphate for AG (2 mg) chitosan nanoparticles based upon charge-neutralization calculation. Aminoglycoside (AG) Streptomycin Gentamicin Tobramycin Formula C21H39N7O12 C19H39N5O7 C18H37N5O9 Number of associated H2SO4 3/2 1 1 Total MW 728 547 565.5 Number of positive charges 3 5 5 Calculated dextran amount (mg) 1.2 2.5 2.4 Conclusion. Dextran sulphate can significantly increase AG incorporation into the chitosan nanoparticles. The concentration of each component was critical in preparing AG-loaded chitosan nanoparticles. The chitosan nanoparticles designed in this study may provide a promising oral drug delivery formulation for AG which usually, in tuberculosis treatment, is administrated as an injectible preparation.

Keywords: Aminoglycoside; oral delivery; chitosan; nanoparticle; streptomycin; gentamicin; tobramycin

Document Type: Research article

DOI: http://dx.doi.org/10.1080/02652040802365182

Affiliations: 1: Department of Biopharmaceutical Science, 2: Institute for Tuberculosis Research, University of Illinois at Chicago, IL, USA 3: Department of Biopharmaceutical Science,Institute for Tuberculosis Research, University of Illinois at Chicago, IL, USA,deCode Genetics, Woodrige, IL, USA

Publication date: 2009-06-01

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