all the reagents used are of laboratory reagent grade and solvents were of analytical grade . ibuprofen and naproxen were provided by macleods pharmaceutical pvt . ltd . as gift samples . high performance liquid chromatography ( hplc ) method has been developed for the determination of purity and stability study of synthesized derivatives . naproxen ( 8) and ibuprofen ( 9 ) were coupled with tropinol ( 3 ) using ethyl dimethylamino propyl carbodimide ( edc ) and dimethylaminopyridine ( dmap ) to obtain the esters ( 4 - 5 ) as oily products . the esters ( 4 - 5 ) were quaternized with methyl iodide to obtain the desired quaternary derivatives ( 6 - 7 ) as shown in scheme 1 . hplc method has been developed for the determination of purity and stability study of the synthesized derivatives in phosphate buffer ph 7.4 and in human plasma . all synthesized derivatives shows good stability in phosphate buffer at ph 7.4 ( half life of disappearance 30 - 45 h ) but get hydrolysed fast in human plasma ( half life 8 - 12 h ) . in order to check the site specific concentration of these quaternary derivatives ( 6 - 7 ) radiolabelling was done using radioactive tc , radiolabeling of the compounds with tc was carried out by direct labeling method to form complex and study their site specific localization tendency in the inflamed tissue . the in vitro stability of radiolabeled complexes was determined in sodium chloride ( 0.9% ) and in human serum . once the complexed derivatives ( tc  qa ) were found to be stable then imaging study was performed in sprague - dawley rats using a single photon emission computerized tomography gamma camera and both derivatives shows higher affinity towards cartilage than parent nsaid . naproxen ( 8) and ibuprofen ( 9 ) were coupled with tropinol ( 3 ) using ethyl dimethylamino propyl carbodimide ( edc ) and dimethylaminopyridine ( dmap ) to obtain the esters ( 4 - 5 ) as oily products . the esters ( 4 - 5 ) were quaternized with methyl iodide to obtain the desired quaternary derivatives ( 6 - 7 ) as shown in scheme 1 . hplc method has been developed for the determination of purity and stability study of the synthesized derivatives in phosphate buffer ph 7.4 and in human plasma . all synthesized derivatives shows good stability in phosphate buffer at ph 7.4 ( half life of disappearance 30 - 45 h ) but get hydrolysed fast in human plasma ( half life 8 - 12 h ) . in order to check the site specific concentration of these quaternary derivatives ( 6 - 7 ) radiolabelling was done using radioactive tc , radiolabeling of the compounds with tc was carried out by direct labeling method to form complex and study their site specific localization tendency in the inflamed tissue . the in vitro stability of radiolabeled complexes was determined in sodium chloride ( 0.9% ) and in human serum . once the complexed derivatives ( tc  qa ) were found to be stable then imaging study was performed in sprague - dawley rats using a single photon emission computerized tomography gamma camera and both derivatives shows higher affinity towards cartilage than parent nsaid . cartilage targeting strategy for the conventional nsaids has been explored for reducing their local and systemic side effects the nsaids . selective concentration of these ester derivatives into the tissue in demand could also allow reduction in their doses . it could be concluded that site specific delivery of these quaternary ester derivatives could prove to be an effective strategy for long term therapy of inflammatory conditions like arthritis .