nanoparticles with incorporated antibiotics are prepared by double emulsion technique or by nanoprecipitation at different drug - to - polymer ratios and water soluble coadjuvants are added to the water phase in various concentrations . after the elimination of organic solvents , a suspension of the formed nanoparticles is concentrated and filtered through a microporous filter membrane . the particle size is measured by photon correlation spectroscopy ( malvern zetasizer “ nano - s ”). for evaluation of drug loading in np , free drug is separated by ultrafiltration ( separation membrane with molecular cutoff 30 , 000 or 300 , 000 nmwl ) and its concentration is measured by hplc . 50 - 500 mg of antibiotic ( streptomycin sulfate usp ) was dissolved in 0 . 5 - 1 . 0 ml of purified water and emulsified in 5 - 10 ml of organic solvent ( ethyl acetate , saturated with water , dry chlorophorm or pure methylene chloride ), containing dissolved d , l - lactide - glycolide copolymer ( e . g ., resomer ® 502 , 503 or 503h , boehringer ingelheim , germany ), with the help of short sonication ( 30 sec ) at 20 khz using titanium indenter or a high shear rotor - stator mixer ( ultra - turrax ® t10 , ika , germany ). the formed emulsion was added to a continuous water phase , containing surfactants and may contain other water soluble adjutants , and further homogenized ( 30 sec sonication , 3 - 5 cycles of high pressure homogenization ( avestin emulsiflex ® c5 or similar machine ). the fine emulsion thus obtained was evaporated under decreased pressure ( 2 - 100 mm hg ) to eliminate organic solvents and concentrate the product to a final volume of 10 ml . the final suspension of nanoparticles was centrifugated ( 10 minutes , 1000 g ) to remove aggregates , and filtrated through 0 . 45 mcm microporous membrane . the particle size and size distribution was measured by photon correlation spectroscopy ( malvern zetasizer ® nano - s ) in water . for evaluation of the drug associating with np , a clear drug solution molecular cutoff 30 , 000 or 300 , 000 nmwl ) and antibiotic concentration was determined by hplc . vancomycin loaded polymeric nanoparticles were obtained by a method similar to that described earlier in ex . 1 - 10 . ethyl acetate was used as an organic solvent , d , l -( poly ( lactic )- poly ( glycolic ) block copolymer resomer ® rg from boehringer ingelheim was used as a matrix material of nanoparticles . drug binding estimation was carried out by transmembrane uitracentrifugation or by sedimentation of the nanoparticles by high speed centrifugation . the final volume of the product — 10 ml , results are shown polymixin b loaded polymeric nanoparticles were obtained by a method similar to that described earlier in ex . 1 - 10 . ethyl acetate was used as organic solvent , d , l -( poly ( lactic )- poly ( glycolic ) block copolymer resomer ® rg from boehringer ingelheim was used as a matrix material of nanoparticles . various counter - ions were used to improve drug incorporation into nanoparticles . drug binding estimation was carried on by transmembrane uitracentrifugation or by sedimentation of the nanoparticles by high speed centrifugation . the final volume of the product — 10 ml , results are shown in table 3 . colistin loaded polymeric nanoparticles were obtained by a method similar to that described earlier in ex . 1 - 10 . ethylacetate was used as organic solvent , d , l -( poly ( lactic )- poly ( glycolic ) block copolymer resomer ® rg from boehringer ingelheim was used as a matrix material of nanoparticles . various counter - ions were used for improvement of drug incorporation into nanoparticles . drug binding estimation was carried out by transmembrane uitracentrifugation . the final volume of the product — 10 ml , results are shown in table 4 . 154 - 167 mg of antibiotic ( amikacin sulfate usp , equal to 100 mg amikacin base ) was dissolved in 0 . 3 - 0 . 5 ml of purified water and emulsified in 5 - 10 ml of organic solvent ( water saturated ethyl acetate ), containing dissolved d , l - lactide - glycolide copolymer ( resomer ®, boehringer ingelheim , germany ) with help of short sonication . the formed emulsion was added to a continuous water phase , containing surfactants and may contain other water soluble adjutants and further homogenized ( 30 sec . sonication , 5 cycles of high pressure homogenization ( avestin emulsiflex ® c5 at 12 , 000 - 18 , 000 psi ). the obtained fine emulsion was evaporated under decreased pressure ( 2 - 100 mm hg ) to eliminate organic solvents and concentrate the product to a final volume of 10 ml . the final suspension of nanoparticles was centrifuged ( 10 minutes , 1000 g ) to remove aggregates , and filtered through a 0 . 45 mcm microporous membrane . the particle size and size distribution was measured by photon correlation spectroscopy ( malvern zetasizer ® nano - s ) in water . for evaluation of the drug associating with np , a clear drug solution was separated by transmembrane ultracentrifugation ( separation membrane with molecular cutoff 300 , 000 nmwl ) and antibiotic concentration was determined by hplc . the final volume of the product — 10 ml , results are shown in table 5 . an investigation of the antituberculosis efficacy of nanoparticulate forms of streptomycin for parenteral administration was carried out in comparison with conventional streptomycin sulfate for injections . mycobacterium tuberculosis strain h 37 rv ( atcc 27294 ) bacteria were grown to mid log phase in difco ™ broth , supplemented with albumin - dextrose - catalase and 0 . 05 % polysorbate 80 . cultures are incubated at 37 ° c . with 5 % co2 and continuous shaking . bacteria are harvested by centrifugation at 5 , 000 g , washed with sterile pyrogen - free saline , concentrated to 3 × 10 8 cfu / ml , aliquoted and stored at − 70 ° c . until use . aliquots are thawed before inoculation . specific - pathogen - free ( spf ) balb / c female mice , weighing 18 - 22 g ., not more then six per cage , were housed in an air - conditioned biohazard room designed for infectious animals model , with temperature 21 ± 2 ° c ., humidity 55 ± 15 % and a 12 - hour light / 12 - hour dark cycle . they have access to food and filtered tap water ad libitum . mice were acclimatized in the animal facilities for 1 week prior to the commencement of the experiment . for inoculation , the frozen stock is thawed , diluted to concentration of 10 8 cfu / ml with sterile pyrogen free 0 . 9 % solution of sodium chloride for injection containing 0 . 01 % polysorbate 80 ( sterile filtered in aseptic conditions ) and sonicated for 2 minutes to disperse clumps . each mouse is inoculated intravenously ( lateral tail vein ) with 10 7 mycobacteria in a volume of 0 . 1 ml . the amount of bacteria used as the inoculation dose was verified retrospectively by serial dilution on middlebrook 7h10 agar , supplemented with oleic acid - albumin - dextrose - catalase . at day 0 ( d0 ) all mice are inoculated intravenously with 10 7 m tuberculosis per mouse . the next day ( d1 ) after bacterial inoculation , 6 infected animals ( baseline control 1 ) were sacrificed to provide baseline values of body , spleen and lung weight , lung lesions , and the number of cfu in the spleen and lungs ( bacterial count ). the remaining mice were divided randomly into experimental groups ( 18 animals in each group ). each experimental group was subdivided into two subgroups of 6 and 12 animals . the first animal subgroup was sacrificed at d28 and the second subgroup was monitored for mortality daily as to lethality for a period of 8 weeks . all surviving animals were euthanized at d56 to perform terminal procedures . treatment with antibiotic is started the day after bacterial inoculation at day 1 ( d1 ) and carried out for 4 weeks ( 28 days ), followed by an additional 28 days of observation . animals from positive control and comparison control groups were treated with streptomycin sulfate for injection ( conventional form ). the route of administration for all experimental groups is intraperitoneal injection , in a dose corresponding to 200 mg / kg of streptomycin base . the positive control group received intraperitoneal injections of streptomycin sulfate in a dosage equal to 200 mg / kg of streptomycin base , 5 times a week for 4 weeks , to a total cumulative dose of 4000 mg / kg . the comparative control group received intraperitoneal injections of streptomycin sulfate in a dosage equal to 100 mg / kg of streptomycin base twice a week for 4 weeks , to a total cumulative dose of 800 mg / kg . nanoparticulate formulations were administrated in a dosage equal to 100 mg / kg of streptomycin base , twice weekly for 4 weeks . experimental results are presented in tables 6 and 7 and graph 1 . animals : male cd - 1 ( charles river laboratory ) mice weighing 24 ± 2 g provided are used . space allocation for animals is 45 × 23 × 21 cm for 10 mice . the animals are housed in animal cages and are maintained in a hygienic environment under controlled temperature ( 22 °- 23 ° c .) and humidity ( 50 % - 60 %) with 12 hours light / dark cycles for at least one week in the laboratory prior to initiation of the study . free access to standard lab food and water supply is allowed . pneumonia model : mice were inoculated intratracheally ( it ) with a ld90 - 100 of staphylococcus pneumoniae ( atcc 6301 ) ( 9 . 7 × 10 6 cpu / mouse ) in 40 μl pbs . in 16 hours , all mice developed pronounced pneumonia , confirmed by histological observation . test formulations and vehicle were diluted with 5 % sterile dextrose and administered intravenously to animals 20 hours after bacterial inoculation . mortality was recorded once daily for 10 days . results for the comparative treatment of severe lung infections with either aminoglycoside antibiotic ( streptomycin ) or glycopeptide antibiotic ( vancomycin ) in nanoparticle colloidal formulations , along with conventional formulations , shows that there is a significant increase in antibacterial activity in the colloidal formulations . a streptomycin formulation according to example # 3 of the invention is at least 5 times more effective than tree streptomycin ; nanoparticulate compositions of vancomycin ( examples # 9 and # 10 ) are approximately 10 times more effective than standard solutions of vancomycin sulfate usp for injection . similar increases in antibacterial efficiency are observed for other antibiotics incorporated in nanoparticulate colloidal delivery systems made of biodegradable polymers ( e . g ., amikacin , kanamycin , gentamicin , colistin , polymixin b , bacitracin , fluoroquinolones ).
colloidal compositions , loaded with non - covalently bonded antibiotics , can be efficiently used for the treatment of severe bacterial pneumonia and other serious lung infections such as tuberculosis . such formulations , comprised of biodegradable nanoparticles or nanocapsules with incorporated antibiotics , show a significant increase in antibacterial activity , extended and sustained drug release and a decrease in frequency of the drug administration . antibiotics of various types , such as aminoglycosides , glycopeptides and others can be successfully incorporated into a nanoparticulate colloidal delivery system .