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Infection / Inflammation / S. aureus / 99m Tc-Vancomycin / Biodistribution in ratsSummary. Vancomycin Hydrochloride is an antibiotic produced by the growth of certain strains of Streptomyces orientalis. As Vancomycin Hydrochloride is poorly absorbed after oral administration; it is given intravenously for therapy of systemic infections. Vancomycin was labeled with technetium-99m pertechnetate using SnCl 2 ·2H 2 O as reducing agent. The labeling efficiency depends on ligand/reductant ratio, pH, and volume of reaction mixture. Radiochemical purity and stability of 99m Tc-Vancomycin was determined by thin layer chromatography. Biodistribution studies of 99m TcVancomycin were performed in a model of bacterial infection in Sprague-Dawley rats. A significantly higher accumulation of 99m Tc-Vancomycin was seen at sites of S. aureus infected animals. Whereas uptake of 99m Tc-Vancomycin in turpentine inflamed rats were quite low.

Diagnosis of deep-seated bacterial infection remains a serious medical challenge. The situation is becoming more severe with the increasing prevalence of bacteria that are resistant to multiple antibiotic classes. Early efforts to develop imaging agents for infection, such as technetium-99m (Tc) labeled leukocytes, were encouraging, but they failed to differentiate between bacterial infection and sterile inflammation. Other diagnostic techniques, such as ultrasonography, magnetic resonance imaging, and computed tomography, also fail to distinguish between bacterial infection and sterile inflammation. In an attempt to bypass these problems, the potent, broad-spectrum antibiotic ciprofloxacin was labeled with Tc to image bacterial infection. Initial results were encouraging, but excitement declined when controversial results were reported. Subsequent radiolabeling of ciprofloxacin withTc using tricarbonyl and nitrido core, fluorine and rhenium couldn't produce robust infection imaging agent and remained in discussion. The issue of developing a robust probe can be approached by reviewing the broad-spectrum activity of ciprofloxacin, labeling strategies, potential for imaging infection, and structure-activity (specificity) relationships. In this review we discuss ways to accelerate efforts to improve the specificity of ciprofloxacin-based imaging.

fac(S)-[Ir(aet) 3 ] (aet = 2-aminoethanethiolate) is N3S3 metalloligand, which forms S-bridged polynuclear complexes with transition metal ions. A complex analogous to [Re{Ir(aet 3 )} 2 ] 3+ was formed by the reaction of 99m TcO 4 Na and fac(S)-[Ir(aet) 3 ] in the presence of SnCl 2 2H 2 O. A simple method for radiollabelling of fac(S)-[Ir(aet) 3 ] with 99m Tc was developed with radiolabelling efficiency higher than 99%. Effects of SnCl 2 ·2H 2 O concentration, time and pH on the radiolabelling efficiency were determined and compared with 99m Tc-[Rh(aet) 3 ]. 99m Tc-[Ir(aet) 3 ] was also characterized by electrophoresis, HPLC, biodistribution studies in rats and scintigraphy in rabbit. Higher uptake by kidneys showed rapid distribution of the labelled fac(S)-[Ir(aet) 3 ]. Scintigrams show that liver, bladder and skeletal uptake were significant. The results of biodistribution showed that 99m Tc-[Ir(aet) 3 ] uptake is quite rapid as compared to 99m Tc-[Rh(aet) 3 ].

Bacterial infection is found to be the cause of death throughout the world. Nuclear medicine imaging with the help of radiopharmaceuticals has great potential for treating infections. In the present work, clindamycin, a lincosamide antibiotic, was labeled with technetium-99 m (~380 MBq). Clindamycin has been proven to be efficient for treating serious infections caused by bacteria such as Staphylococcus aureus. Quality control, characterization, biodistribution, and scintigraphy of radiolabeled clindamycin were done, and labeling efficiency was determined by ascending paper chromatography. More than 95 % labeling efficiency with technetium-99 m ((99m)Tc) was achieved at pH 6-7 while using 2.5-3 μg SnCl2 · H2O as a reducing agent and 100 μg of ligand at room temperature. The characterization of the compound was performed by using electrophoresis, HPLC and shake flask assay. Electrophoresis indicates the neutral behavior of (99m)Tc-clindamycin. HPLC analysis confirms the single specie of the labeled compound, while shake flask assay confirms high lipophilicity. The biodistribution studies of (99m)Tc-clindamycin were performed Sprague Dawley rats bearing bacterial infection. Scintigraphy and biodistribution studies showed a high uptake of (99m)Tc-clindamycin in the liver, heart, lung, and stomach as well as at S. aureus-infected sites in rabbits.

SummaryIsonicotinic acid hydrazide (isoniazid) is one of the most effective agents in tuberculosis therapy. Hence it was chosen as ligand for

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PHOTOFRIN® was labelled with 99mTc using SnCl2·2H2O as reducing agent. Instant thin layer chromatography (ITLC-SG) in 0.05 M NaOH was used for evaluation of radiochemical purity. Labelling efficiency was dependent on various factors that include the ligand/reductant ratio, pH and time of incubation. Therefore, optimum conditions of labelling were also determined. The stability of 99mTc-PHOTOFRIN® in serum was checked by using fresh human serum. Tissue distribution of 99mTc-PHOTOFRIN® was evaluated in Sprague Dawley rats. PHOTOFRIN® was labelled with an efficiency of >95% under optimum conditions, which were PHOTOFRIN®: 200 μg, pH: 3–4, SnCl2·2H2O: 15 μg and 30 min incubation at room temperature. The 99mTc-labelled PHOTOFRIN® remained stable in human serum for 24 h. Biodistribution study in rats revealed maximum concentration of the labelled compound in liver, lungs and spleen at 0.5 h, and significant activity was also seen in the bladder and urine, indicating the mode of urinary excretion of PHOTOFRIN®.