J. Chil. Chem. Soc., 62, Nº 1 (2017) 3345 SYNTHESIS, QUALITY CONTROL AND BIODISTRIBUTION OF TECHNEIUM-99M TRIAMCINOLONE ACETONIDE ( 99m Tc-TA) COMPLEX: AN INFLAMMATION TRACER AGENT FAHEEM ASKARI RIZVI 1 , SYED ALI RAZA NAQVI 1* , MUHAMMAD MEHDI 1 , SAMINA ROOHI 2 , AMEER FAWAD ZAHOOR 1 , ZULFIQAR ALI KHAN 1 , MUHAMMAD SOHAIB 4 AND RASHID RASHEED 1,3 1 Department of Chemistry, Government College University Faisalabad, Pakistan. 2 Isotope Production Division, Pakistan Institute of Nuclear Science and Technology, P.O. Nilore, Islamabad, Pakistan. 3 Institute of Nuclear Oncology and Radiology (INOR), Abbottabad, Pakistan. 4 Department of Medical Sciences, Pakistan Institute of Engineering and Applied Sciences, (PIEAS) Islamabad Pakistan. ABSTRACT In present study synthesis of 99m Tc-triamcinolone acetonide ( 99m Tc-TA) complex and its stability using set of quality control parameters such as ligand con- centration, reducing agent concentration, pH, temperature and reaction time was assessed. 99m Tc-TA complex was characterized in terms of percent (%) yield, stability in saline and serum using chromatographic procedures. Radiochemically the 99m Tc-TA complex was found quite stable in saline and serum. After 30 min of reaction the complex showed maximum radiochemical yield of 96.32% which decreased to 96.25 % after 4 h incubation period. In serum, the % yield of radio- chemical was remained same up to 2 h which decreased to 93.5% at 24 h time point. Normal biodistribution pattern in Sprague-Dawley rats revealed liver, stomach and kidneys as areas of high 99m Tc-TA complex uptake (8.44 ± 1.32, 8.75 ± 1.03 and 12.67 ± 1.21%, respectively) at 1 h post injection time point. Scintigraphy of 99m Tc-TA in rabbits showed similar eco as observed in biodistribution study. Based on the promising results obtained in context of in vitro and in vivo stability and biodistribution, 99m Tc-TA complex could be further studied to identify the infammation based diseases. Key words: 99m Tc-Triamcinolone, Electrophoresis, Biodistribution study, Scintigraphy of Rabbits, Serum Stability. e-mail: draliraza@gcuf.edu.pk 1. INTRODUCTION With the invention of radiopharmaceuticals to study disease status, extensive debate was reported to manage worldwide infection threat. Within few decades thousands of repots were published to address early diagnosis strategy using radiolabeled compounds. 1-3 Although very sensitive and sophisticated diagnostic modalities such as computed tomography (CT) and magnetic resonance imaging (MRI), and number of biochemical testsare in use worldwide to assess infectious and malignant diseases, the radiopharmaceuticals were developed for early diagnosis and targeted therapy. The only bottlenecks associated with CT and MRI scan are their diagnostic ability after certain morphological and entomological changes in diseased body tissues, and absence of discrimination potential between infection and infammation. 4 Various radiopharmaceuticals, such as radiolabeled white blood cells, 5,6 antibiotics, 7 synthetic organic moieties, 8 antimicrobial peptides, 3 antibodies, 9 and peptide hormone analogue 10,11 have been developed in pursuing early detection of infection and malignancies. The radiolabeled leukocytes, 12 citrate, 13 human polyclonal immunoglobulin (HIG), 14 ubiquicidin-29-41 peptide 15 and antibiotic 1,7 were studied to diagnose and discriminate infections from infammations. 16 One of the clinically most popular antibiotics, ciprofoxacin was labeled with Technetium-99m (Tc- 99m/ 99m Tc) and provided to oncological centers with trade name infecton® for specifc imaging of infections. 17 However, previous and recently reported data showed contradiction while discriminating infection from infammation. 18 Other antimicrobial agents belonging to different classes of antibiotics specifcally from fouroquinolones and cephalosporin family were also investigated to overcome non-specifcity issue but the required and potential results were not achieved 16,19 Triamcinolone acetonide (TA), a synthetic glucocorticoid i.e. fuoroquinolones used as a potential anti-infammatory agent under certain conditions such as eczema, psoriasis, arthritis, allergies also including ulcerative colitis, sympathetic ophthalmia, and ocular infammations. 20 It also appeared as an anticancer agent. The anti-infammatory properties of this compound have been demonstrated to inhibit the expression of the VEGF gene. 21,22 In present study, we describe the radiolabeling of TA with Tc-99m (Figure 1), in vitro saline and serum stability, normal biodistribution in rats and scintigraphic imaging using rabbits for potential infammationimaging agent. 2. EXPERIMENTAL 2.1. Materials and methods Triamcinolone acetonide was obtained from Sigma-Aldrich, ITLC from Agilent (Germany), Deluxe electrophoresis chamber (Gelman) system (Germany), Rats (Spragur-Dawley) from NationalInstitute of Health (NIH) Islamabad. All chemical used were on analytical grade (Sigma-Adrich). Technetium-99m was obtained from a locally situated fssion based Pakistan generator (PAKGEN) 99 Mo/ 99m Tc generator (PINSTECH, Islamabad). The animal ethics committee of the institute gave an ethical approval for the animal experiments. 2.2. Synthesis of 99m Tc-TA complex In six sterilized nitrogen flled vials, reducing agent (SnCl 2 .2H 2 O) 2-5 µg with an increment of 0.5 µg were taken. Then, ~ 370 MBq 99m TcO 4 - saline solution (0.8 mL) was added in each vial. Thereafter, 100 to 600 mg TA with an increment of 100 mg was added in each vial. The pH of each vial (reaction mixture) was adjusted 3 to 8 with 1 unit rise followed by incubation at room temperature and starts to monitor radiolabeling from 5 min to 6 h with defnite time intervals. 2.3. Quality control Radiochemical yield of 99m Tc-TA was assessed by ITLC-SG strips Whatman No. 3 paper. For this purpose 4 µL of reaction mixture was spotted at base line on Whatman No. 3 paper and developed with acetone to determine free 99m TcO - 4 using. While 2 µL reaction mixture was spotted at base line on ITLC-SG strip and developed with 0.5 M NaOH solution to determine reduced and hydrolyzed fractions After complete development the both radio- chromatograms were dried and scanned with 2π-Scanner (Berthold, Germany). The radiochemical complex stability was monitored periodicallyfor 24 h at room temperature. Each experiment was repeated thrice. 2.4. In vitro stabilityin human serum In vitro effect of blood serum on stability of the 99m Tc-TA was studied by mixingserum (1.8 mL) with 99m Tc-TA (0.2 mL) followed by incubation at 37 ºC. At pre-defned time points up to 24 h, 0.2 mL aliquots were withdrawn and spotted at ITLC to determine the percent of 99m Tc-TA, reduced hydrolyzed 99m Tc and free 99m TcO - 4. 2.5. Electrophoresis of 99m Tc-TA The qualitative net charge on 99m Tc-TA was determined with electrophoresis procedure. The process was carried out by spotting 0.2 mL 99m Tc-TA at the center of the 30 cm long strip of Whatman No. 1 chromatographic paper. Electrophoresis was run for 60 to 90 min at a voltage of 300 V usingphosphate buffer of pH 6.8. After completion of electrophoresis, the strip was scanned by using 2π scanner to know the charge on 99m Tc-TA complex. 2.6. Biodistribution study of 99m Tc-TA in normal rats Biodistribution in normal animal model was performed usingmale Sprague-Dawley rats weighing ~250 g. The distribution protocol was used as described previously. 2 Before administration of 99m Tc-TA, the rats were properly monitored atleast for one day.On the day of biodistribution study, 0.2 mL of 99m Tc-TA (~110 MBq) was injected into the tail vein. Three rats were used for one set of experiment. After a defnite time, the rats were sacrifcedby the decapitation under chloroform anesthesiaat 1, 4 and 24 h post-injection. One milliliter samples of blood were collected by cardiac puncture at the time of