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ABSTRACT
Year : 2010  |  Volume : 25  |  Issue : 3  |  Page : 78-87 Table of Contents   

Radiopharmacy


Date of Web Publication25-Nov-2010

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How to cite this article:
. Radiopharmacy. Indian J Nucl Med 2010;25:78-87

How to cite this URL:
. Radiopharmacy. Indian J Nucl Med [serial online] 2010 [cited 2019 Jul 17];25:78-87. Available from: http://www.ijnm.in/text.asp?2010/25/3/78/72755

RPY 01 (ORAL)

Noninvasive assessment of tumor hypoxia with 99mTc labeled Schiff base derivative of metronidazole

Pandey AK 1,2 , Hazari 1 Puja P, Kamlesh K Meena,

Patnaik R 2 , Mishra AK 1

1
Institute of Nuclear Medicine and Allied Sciences, DRDO, Delhi, 2 School of Biomedical Engg, Institute of Technology, Banaras Hindu University, Varanasi, India

Introduction: The presence of hypoxic cells in cancerous lesions is believed to be one of the major reasons for the failure of radiotherapy. Metronidazole is a nitroimidazole derivative which has a tendency to accumulate in the hypoxic regions. Imidazoles are reduced intracellularly in all cells, but in the absence of adequate supplies of oxygen, they undergo further reduction to more reactive products that bind to cell components. The reduction pathway can proceed in successive steps past the hydroxylamine derivative to terminate at the relatively inactive amine derivative. This leads to the possibility of envisaging these compounds as radiosensitive, the agents, which enhance the lethal effect of ionizing radiations for hypoxic tissues. Materials and Methods: Metronidazole was reacted with 2-iodoxybenzoic acid followed by the subsequent reaction with diethylenetriamine resulting into synthesis of Schiff base derivative which was characterized on the basis of spectroscopic techniques. Radiocomplexation was performed with 99mTc for in vivo tumor imaging applications, blood kinetics and biodistribution studies of the radiotracer developed. Result: The newly synthesized schiff base of metronidazole was fully characterized by spectroscopic techniques, 1H, 13C NMR, mass spectroscopy and IR spectroscopy. The radioconjugate was found to be sufficiently stable in vitro as well as in vivo upto 24 h. Blood clearance of the radiotracer in rabbit was found to be more rapid (t1/2(F)=27±1.4 minutes) and t1/2(S)=3hr 48±8.4 minutes). The biodistribution in athymic mice showed high tumor uptake (4.93±0.22% ID/g and low normal organs uptake. Conclusion: Above results showed that 99mTc labeled compound acts as a specific marker accumulated in hypoxic tumor. Excellent biodistribution characteristics support the concept of its utility as specific radiopharmaceutical for imaging hypoxic tumors.

Keywords: Tumor, hypoxia, metronidazole derivatives

RPY 02 (POSTER)

Tc-99m-O 2 S 4 : A new generation hepatobiliary imaging agent

Babbar AK, Mathur R, Yadav A 1 , Katiyar N, Dutta M, Flora, and Mishra AK


INMAS, Brig SK Mazumdar Road, Delhi, 1 DRDE, Gwalior, India

Abstract: Hepatobiliary imaging radionuclide Tc-99m-Mebrofenin is indicated as a hepatobiliary imaging agent for the evaluation of hepatobiliary tract patency to differentiate jaundice resulting from hepatocellular causes from jaundice resulting from partial or complete biliary obstruction; to differentiate extrahepatic biliary atresia from neonatal hepatitis; to detect cystic duct obstruction associated with acute cholecystitis; and to detect bile leaks. Also, Tc-99m-Mebrofenin may be useful to detect intrahepatic cholestasis and to distinguish it from other hepatobiliary diseases, which involve hepatocyte damage. However, the mebrofenin kit has to be obtained at an exorbitant cost and there was need to develop an indigenous kit that was readily available and could give similar results. For the first time in India, a derivative of DMSA developed by DRDE, Gwalior and modified at INMAS, Delhi to adopt early transition metals, was successfully labelled with Tc-99m (LE>99%). The reaction conditions were optimized after studying the effects of amount of SnCl 2 , pH of the reaction and effect of incubation time. The labelled product Tc-99m-O 2 S 4 , was characterized by ITLC-SG using acetone and saline. The complex was found to be fairly stable at room temperature and showed>95% plasma protein binding. The biodistribution studies showed that after intravenous administration, there was immediate accumulation of radioactivity in liver, the activity kept on increasing in gall bladder with time and thereafter the radioactivity moved to common bile duct (CBD) and small intestines. No significant radioactivity was found in kidneys and blood. Clear visualization of the gallbladder and intestines, within 15 to 45 minutes of administration of Tc-99m-O 2 S 4 in normal rabbit, demonstrates hepatobiliary tract patency of the newly developed radiotracer. The dynamic and static images showed that the newly developed radiopharmaceutical Tc-99m-O 2 S 4 has full potential in studying the various ailments of hepatobilliary route. The extraction time of Tc-99m-O 2 S 4 from various organs is being studied and shall be compared with that of Tc-99m-Mebrofenin.

Keywords: New radiopharmaceutical, Tc-99m-Mebrofenin, hepatobiliary imaging

RPY 03 (POSTER)

Comparative evaluation of newly developed Tc-99m-O 2 S 4 and conventionally used Tc-99m-Mebrofenin as hepatobiliary imaging agent

Babbar AK, Katiyar N, Mathur R, Yadav A 1 , Flora SJS 1 , Mishra AK


INMAS, Brig SK Mazumdar Road, Delhi and 1 DRDE, Gwalior, India

Technetium-99m labelled imminodiacetic acid (IDA) drivatives are commonly used as hepatobiliary imaging agents to evaluate hepatic functions, biliary duct patency and also in cholescintigraphy. Of more than thirty IDA derivatives studied so far, DISIDA and mebrofenin are the most widely accepted hepatobiliary agents. We at INMAS, have successfully radiolabelled O 2 S 4 , a derivative of DMSA developed by DRDE Gwalior and further modified at INMAS. The newly developed agent Tc-99m-O 2 S 4 was compared with Tc-99m-Mebrofenin for uptake and clearance from the hepatic system of a normal rabbit. Both the radiopharmaceuticals were administered intravenously to normal rabbits of same weight and dynamic as well as static images were acquired at various time intervals. Both the agents were accumulated in liver almost immediately after administration and extraction of radioactivity in gall bladder (GB) started almost immediately. The extraction of Tc-99m- O 2 S 4 to GB was slower as compared to that of Tc-99m-Mebrofenin. However, the radioactivity kept on draining out from liver and GB was well visualized in both the cases within a few minutes. At 20 minutes post administration, the liver had very little activity in case of Tc-99m-Mebrofenin whereas of Tc-99m-O 2 S 4 was still present. From the billiary tree the radioactivity moved to common bile duct and duodenum, which took almost same time in both cases. The only difference between the two agents was rate of extraction of radioactivity from liver during initial time. After 30 minutes post injection, both agents behaved almost in similar fashion. Further studies on dependence of Tc-99m-O 2 S 4 on billirubin and effect of billirubin levels on uptake in GB are being studied

Keywords: Tc-99m-O2S4, hepatobiliary imaging agent, Tc-99m-Mebrofenin

RPY 04 (ORAL)

Non-HPLC methods for the production of F-18, C-11 and Ga-68 PET tracers

Yordanov Alexander, Llop J 1 , Stimson D 2 , Combs MJ, Mueller M 3 , Soylu A 4 , Bagci H 4 , Shulman S


Bioscan, Inc., Washington, DC, USA. 1 CICbioMAGUNE, San Sebastian, Spain 2 Royal Brisbane Hospital, Brisbane, Queensland, Australia 3 ABX Advanced Biochemical Compounds, Radeberg, Germany 4 Ezcacibasi-Monrol, Ankara, Turkey

The most popular PET radionuclides in routine clinical use are C-11 and F-18, although other radionuclides, such as Ga-68, continue to make headlines. This is due to their well established chemistry, their utility for labeling low molecular weight compounds, and their ease of production in modern PET cyclotrons or via commercially available generators. Their relatively short halflives, along with the global trend toward Good Manufacturing Practice in PET drug production has necessitated the development of aseptic, robust and rapid labeling methodologies. This is achieved by the use of automated radiochemistry systems, which, in turn, has allowed radiosynthesis scale-up and multiple dose preparation. Major impediments to routine production of a number of useful C-11, F-18 and Ga-68 PET tracers, and to new tracer development, remain: 1) the necessity of thorough system clean up in between consecutive runs; and 2) inconsistent yields and prolonged synthesis time when using HPLC methods for final product separation and purification. To address these issues, new radiochemistry applications have been developed for the radiochemistry modules: a) for F-18: FLT Lite, F-MISO Lite, F-Choline Lite, and FET Lite; b) for C-11: Acetate, Methyl Iodide, Methionine, Choline; c) for Ga-68: DOTA-Peptides. These methods utilize sterile disposable kits, and allow for the PET tracers to be purified and isolated with SPE cartridges only, thus eliminating the need for HPLC separation. The processes and the radiochemical yields obtained with these methods will be presented, and their utility discussed.

Keywords: Automated radiochemistry system, PET tracers, NON- HPLC methods

RPY 05 (POSTER)

99mTc(CO) 3 - Nitrofuryl thiosemicarbazone a novel infection imaging agent

Nayak Dipak Kumar, Halder KK, Debnath MC 1


Indian Institute of Chemical Biology, Kolkata, India

Introduction: To develop a potential Technetium labeled infection imaging agent 5-NTS prepared and labeled and its scientigraphic imaging done in rat model. Objective: Diagnosis of deep seated infection is a very challenging problem. Differentiation between bacterial infection and sterile inflammation is also difficult. As thiosemicarbazone compound show antibacterial activity, so a new infection imaging agent was prepared. Their in-vitro and in-vitro stability studies, through biological screening and scientigraphic imaging of the chelates labeled with 99mTc studied on infected thigh muscle tissues in rat model. Materials and Methods: Synthesis of 5-nitrofural thiosemicarbazone An equimolar mixture of 5 nitrofurral and thiosemicarbazide was stirred with p-TsOH (catalytic amounts) in dry tolune. Synthesized compound characterized by 1H-NMR and ESI-MS. The synthesized compound labeled with 99mTc(CO) 3 precursor and 99mTc-oxo(V) core using stannous chloride reduction method. Labeled compound was characterized by TLC in acetone, brine, and ethanol: water: acetic acid: pyridine (1:5:5:1) and also with reverse phase C-18 column. In-vitro stability study was tested in challenge assay with increasing concentration of DTPA (0, 102, 103, 104, 105 molar excess) for 4 hour. Serum stability was also done and its stability analyzed at 0, 2, 8, 18, 24 hour. Infection was induced in rats (Sprague Dawley, 200-220gm) by injecting 0.2 ml of freshly prepared harvested culture of S. aureus (2Χ108cfu) in left thigh muscle. One day after when the infection was apparent, radiopharmaceutical (185-259 kBq/0.1ml) was injected intravenously. For comparison sterile inflammation was induced by an intramuscular injection of 0.1ml of Terpentine oil I. P. to left thigh muscle. The infected animal with radiopharmaceuticals sacrificed at 1, 4, 8, 24 hour post injection, desired organ were collected and transferred to counting vials. Blood samples were obtained by puncture of the heart. Results: Expressed as percent dose/gm of tissue and percent dose/organ. Scientigraphic imaging done at 4 hour post injection in GE Infinia Gamma Camera equipped with Xeleris work Station. Conclusion: Synthesized compound successfully labeled and its scientigraphic imaging show it as a novel infection imaging agent.

Keywords: Nitrofuryl thiosemicarbazone, 99mTc(CO) 3 , infection

RPY 06 (ORAL)

Evaluation of BRIT designed prototype 99mTc generator based on solid phase extraction method: In house experience

Shimpi, Rajan MGR, Nayak UK 1 , Sachdev SS 2 , Ajori P, Goomer NC 3

1Radiation Medicine Center, BARC, 2 BRIT, BARC, VSAHI, Navi Mumbai, 3 Regional Centre, BRIT, DAE, India

Radiation Medicine Centre is planning to start Centralized radiopharmacy, where 99mTcO 4 - activity will be supplied to the other centers. 99Mo-99mTc generators manufactured using fission -produced 99Mo are routinely employed on regular basis at various centers. The 99mTc activity from this generator diminishes with each passing day and it gives shortage of 99mTc activity for many studies at the end of the week. Centralized radiopharmacy will be able to supply a fixed amount of 99mTcO 4 - throughout the week to the various centers. For the regular supply of 99mTcO 4 - activity conventional and non-conventional methods of 99Mo -99mTc generator systems will be used. We have explored the utility of recently developed BRIT prototype 99Mo -99mTc generator system for its application in Centralized radiopharmacy. The Technique entails the use of solid phase extraction method. The 99mTc was separated from 99Mo by loading 99mTc from 99MoO 4 -2 solution on compact solid-phase extaction column and 99mTc activity was eluted with phase-transfer salt TBAB acetonitrile solution This 99mTc in TBAB was further passed through another column to remove organic phase and TBAB. 99mTc is eluted in normal saline from this column. The eluted 99mTc was purified by using alumina column and sterilized by passing through 0.22mm membrane filter. The field trial of this system is carried out at RMC, BARC. It was examined with respect to its performance, quality, safety and lacunae from end-user point of view. It was found that the 99mTcO 4 - yielded was free of contaminants in 58-75% yield This first prototype device is not an automated form. The system though effective for elution of 99mTcO 4 , required some modifications from utility point of view. We have suggested few modifications in the design of the assembly to facilitate manipulation of the system in hospital radiopharmacy. The modified 99mTc Generator incorporating Peristaltic pumps for liquid transfers and sterilization of eluted 99mTc has now been developed at BRIT for further evaluation. However, for Centralized radiopharmacy fully automated 99mTc Generator would be desirable

Keywords: Solid phase extraction, 99mTc Generator, central radiopharmacy

RPY 07 (ORAL)

Role of glycosphingolipids in metabolism of Alzheimer's associated ί-amyloid precursor protein

Tamboli Irfan Y, Hampel H and Walter J


Department of Neurology, University of Bonn, Germany

Alzheimer's disease is associated with extracellular deposits of ί-amlyoid peptides (Ab) in the human brain. The generation of Ab involves sequential cleavages of the ί-amyloid precursor protein (bAPP) by b- and g-secretase. Since bAPP as well as the secretases are integral membrane proteins, the lipid composition of cellular membranes might play regulatory roles in the generation of Ab. Here we sought to identify the role of glycosphingolipids (GSLs) in the proteolytic processing of bAPP. To achieve this, first we inhibited glycosyl ceramide synthase (GCS) that catalyzes the first step in GSL biosynthesis. The GSLs depletion reduced the secretion of bAPP and Ab. In the GSLs deficient cell line GM95, cellular levels and maturation of bAPP were reduced as compared to normal B16 cells. Additionaly, RNAi suppression of lactosyl ceramide synthase (LCS) that catalyzes the second important step in GSL biosynthesis decreased cellular and secreted bAPP. On the other hand, addition of exogenous brain gangliosides to cultured cells increased secretion of bAPP, Ab as well as caused accumulation of APP-CTFs. By biochemical and cell biological experiments, we demonstrate that the GSLs stabilize APPCTFs and thereby increase Ab levels. Together, these data demonstrate that GSLs are implicated in the metabolism of bAPP as well as APP-CTFs. Conclusions: GSLs regulate APP expression, maturation and secretion Inhibition of GSLs biosynthesis reduces levels of Aί, whereas addition of exogenous GSLs led to increased Aί Sphingolipids, including GSLs cause accumulation of APP-CTFs GSLs stabilize APP-CTFs by decreasing their turnover GSLs also promote the g-secretase activity directly Thus, sphingolipids lead to increased intracellular and extracellular Aί by regulation of APP and APP-CTFs metabolism.

Keywords: Glycosphingolipids, Alzheimer's associated b amlyoid protein

RPY 08 (POSTER)

Phytomodulatory effects of Azadirachta indica on
7,12 Dimethylbenz(a)anthracene induced hepatotoxicity and its anticancer activity

Sati Jasmine, Koul Ashwani


Department of Biophysics, Basic Medical Sciences Block, Panjab University, Chandigarh 160014, India

Considering the anticancer and hepatoprotective properties of Azadirachta indica, the present study was designed to evaluate the preventive effects of Aqueous Azadirachta indica leaf extract (AAILE) and Ethanolic Azadirachta indica leaf extract (EAILE). The present study indicated that EAILE has been shown to cause cell death of prostrate cancer cells (PC-3) by inducing apoptosis as evidenced by a dose dependent increase in DNA fragmentation. Western blot studies indicated that treatment with EAILE showed decreased level of Bcl-2, which is anti-apoptotic protein and increased the level of Bax protein. So the neem extract could be potentially effective against prostrate cancer treatment. The hepatoprotective role of AAILE and EAILE against 7,12 Dimethyl benz(a)anthracene induced hepatotoxicity was studied. Female Lacca mice were divided into six groups on the basis of their respective treatments wherein Group I served as controls, mice of Group III and IV were administered AAILE thrice a week throughout the experiment, mice of Group V and VI were administered EAILE thrice a week throughout the experiment and mice of Group II, IV and VI were injected intra peritonially with 7,12 Dimethyl benz(a)anthracene (DMBA) after a period of 12 weeks. DMBA insult in AAILE pretreated animals showed marked decline in formation of MDA suggesting the preventive effects of AAILE against DMBA induced lipid peroxidation as compared to EAILE. Glutathione (GSH) content and the activities of GSH-based antioxidant enzymes viz. glutathione-S-transferase (GST), glutathione peroxidase (GPx), glutathione reductase (GR), catalase and super-oxide dismutase (SOD) were found to be elevated in AAILE and EAILE but the increase in EAILE was more as compared to AAILE. The histoarchitecture of the hepatic tissues of EAILE/AAILE treated animals when challenged with DMBA was found to be near normal. Significance of these observations with respect to the hepatoprotective efficacy of A. indica has been discussed in the present manuscript.

Keywords: Azadirachta indica, apoptosis, Bcl-2, Bax, 7,12 Dimethyl benz(a)anthracene

RPY 09 (ORAL)

5-HTP(hydroxytryptophan) based SPECT imaging agent for visualization of neuroendocrine tumors

Chuttani Krishna, Hazari Puja P, Mathur R, Dutta M, Mishra AK


Division of Cyclotron and Radiopharmaceutical Sciences, Institute of Nuclear Medicine and Allied Sciences, Brig. S. K. Mazumdar Road, Delhi-110054, India

Neuroendocrine tumors are a heterogenous group arising from neuroendocrine cells and include carcinoid,gastroenteropancreatic, pituitary, medullary carcinoma of the thyroid and phaeochromocytomas and are slow growing tumors.In PET imaging 11C-labelled 5-HTP has proved better than CT and somatostatin receptor scintigraphy for visualization of these tumors. 5-HTP is a naturally occurring amino acid and chemical precursor as well as metabolic intermediate in the biosynthesis of the neurotransmitters serotonin and melatonin from tryptophan. Efforts were made to label it with Tc-99m through introduction of a acyclic chelating group (DTPA) and use it as a SPECT imaging agent for the diagnosis of neuroendocrine tumors. Labeling was done using stannous chloride as the reductant. The labeled complex was highly stable both in vitro and in vivo conditions, the clearance pattern from the ciculation was very fast with T1/2(F) 46 min and T1/2(S) 18h 30 min. The biodistribution pattern in mice exhibited maximum accumulation in kidneys followed by liver and intestines. T/NT ratio of 5:1 was achieved at 1h in Ehrlich Ascitis tumor implanted in Balb/c mice which retained upto 4h and even at 24h it was found to be 3.2:1.However its uptake in the specific tumor, receptor binding remain to be elucidated from further studies. But its strong binding with 99mTc, fast blood clearance and appreciable activity accumulation in EAT definitely prove its potential usefulness as a SPECT imaging agent for visualization of neuroendocrine tumors.

Keywords: Neuroendocrine tumors, SPECT, Hydroxytryptophan

RPY 10 (POSTER)

Development and in vitro evaluation of an oral floating matrix tablet formulation of calcium di-sodium EDTA using gamma scintigraphy

Kumar N, Aji Alex MR, Mittal G, Soni S, Nishad DK, Singh T, Ahmad FJ 1 and Bhatnagar A


Institute of Nuclear Medicine & Allied Sciences (DRDO), Brig. S.K. Mazumdar Road, Timarpur, Delhi-54. 1 Faculty of Pharmacy, Jamia Hamdard, Delhi-62, India

Heavy metal poisoning remains a widespread problem in most industrial nations. People exposed to these heavy metal while come in contact heavy metal industries. Toxicity is more likely to result through inhalation or ingestion route. It affects a number of important body functions including central nervous and haematopoietic systems, besides hepatic and renal functions. Metal toxicity has also been reported to cause oxidative stress, leading to various physiological malfunctions. Rapid gastrointestinal transit could result in incomplete drug release from the drug delivery system above the absorption zone leading to diminished efficacy of the administered dose. In order to overcome above mentioned problem we have developed a floating drug delivery system of Calcium disodium edetate (CaNa2EDTA) to provide prolong chelation therapy against various heavy metals. Floating matrix tablets of Ca Na2EDTA were found to attain prolonged gastric residence time. A radiolabeling procedure of Ca-disodium-EDTA with 99mTc was standardized using stannous chloride as reducing agent.The radiolabeled complex was added to the optimized tablet. Floating tablets were prepared by wet granulation technique, usingpolymers such as Hydroxy propyl methyl cellulose (HPMC, Methocel K100M CR), sodium alginate, Chitosan alone or in combination and other standard excipients. Sodium bicarbonate was incorporated as a gas-generating agent. The effects of sodium bicarbonate and poly vinyl alcohol on drug release profile and floating properties were investigated. Dissolution studies were performed to ensure that there was no leaching of radioactivity from the capsules. Gamma scintigraphy was performed in healthy human volunteers to assess the buoyancy of the optimized formulation. The optimized formulation remained buoyant during 4 hours of gamma scintigraphic studies in rabbits.

Keywords: Calcium di-sodium EDTA, gastroretentive, floating drug delivery system, controlled release, gamma scintigraphy

RPY 11 (POSTER)

Evaluation of calcium di-sodium EDTA intramuscular injection using gamma scintigraphy against heavy metal poisoning

Kumar N, Soni S, Mehra L, Mittal G, Nishad DK, Singh T 1 , Ahmad FJ 1 , Bhatnagar A


Institute of Nuclear Medicine and Allied Sciences (DRDO), Brig. S.K. Mazumdar Road, Timarpur, Delhi-54, 1 Faculty of Pharmacy, Jamia Hamdard, Delhi-62, India

Heavy metals become toxic when they are not metabolized by the body and accumulate in soft tissues. These metals may enter the body through food, water, air or absorption through skin when an individual is exposed to areas with high heavy metal content such as agriculture, pharmaceutical manufacturing, paint and heavy metal industries or residential settings. Majority of population commonly get affected by heavy metal poisoning. Heavy metal poisoning is more likely to result through inhalation or ingestion route. Aim of the present study is to provide an easy, effective and controlled chelating therapy against heavy metal using Ca- disodium EDTA intramuscular injection. Ca-disodium-EDTA and Sesame oil were procured from Merck, India and Sigma Aldrich, USA respectively. Ca-Na2EDTA radiolabeling with 99mTc-pertechnetate was standardized using stannous ions as reducing agent. The hypothesis of present work is to maintain effective concentration of chelating agent in blood for prolong time period. To test this hypothesis, we studied 1% Ca-Na2EDTA blood bioavailability after intramuscular depot administration in newzealand white rabbit. The optimized radiolabeled intramuscular formulation was evaluated for its dissolution and permeation studies in isotonic buffer solution were envisaged through radiometry. Sub-acute toxicity studies were performed after a single dose intramuscular administration of 1% Ca-Na2EDTA in sprague dawley rats. Radiolabeled Ca-disodium-EDTA (>95% labeled) was found to be fairly stable up to 24 h in physiological solution (Serum) as well as in normal saline with negligible degradation of 2.5% and 5.0% respectively, thereby indicating high stability of radiolabeled product. In-vitro data indicates that control release pattern (Cmax 24 hrs) with effective concentration up to seven days. 99mTc-CaNa2EDTA retention at depot site was estimated up to 3 days by scintigraphy. Subacute toxicity studies done by histopathological investigation of rat muscle and no significant alterations were detected in pathological examinations of the tissues in comparison to control group animals. Conclusively this studies indicates that Ca- disodium EDTA i.e. injection is stable, safe and may be effective in chelation of various heavy metal on single dose i.m. depot.

Keywords: Ca-disodium EDTA, heavy metal toxicity, i.m. depot, blood clearance

RPY 12 (ORAL)

In vitro and pharmacokinetic evaluation of copper-64-labeled αvβ3 targeted novel polymeric nanoparticles for cancer and cardiovascular imaging

Shokeen Monica, Pressly Eric D 3,4 , Hagooly Aviv, Zheleznyak Alexander, Ramos Nicholas, Fiamengo Ashley L, Welch Michael J 2 , Hawker Craig J 3,4,5 , Anderson Carolyn J 1,2


Mallinckrodt Institute of Radiology, 1 Department of Chemistry and 2 Department of Biochemistry and Molecular Biophysics, Washington University in Saint Louis; 3 Materials Research Laboratory, University of California Santa Barbara, 4 Materials Department, University of California Santa Barbara and 5 Department of Chemistry and Biochemistry, University of California Santa Barbara.

Nanotechnology is currently at the crossroads of revolutionizing the field of diagnostic and therapeutic medical applications. Significant advances have taken place in the design and application of nanoparticle based drug delivery platforms, largely due to the interdisciplinary contributions from chemistry, cell biology, clinical and imaging sciences. In comparison to small molecules, nanoparticles offer promise of better circulation half-life (bio-availability), tolerance for enzymatic degradation (bio-compatibility), physical and chemical stability, and drug release kinetics at the target site. Herein, we describe the in vitro and pharmacokinetic evaluation of a series of polymer nanoparticles with active targeting ligands and diagnostic/imaging units synthesized with the loading of the chain end functionalized, GRGDS peptide targeting sequence ranging from 0 to 50%. The overall goal of the project was to study the impact of structure/activity relationship and multivalency on integrin binding, cellular internalization and pharmacokinetic profile. In cellulo results show an increase in cellular uptake in αvβ3 integrin-positive U87MG glioblastoma cells with increasing RGD loading and a possible upper limit on the effectiveness of the number of RGD peptides for targeting αvβ3 integrin. Significantly, this increased targeting efficiency is coupled with in vivo biodistribution results which show decreased blood circulation and increased liver uptake with increasing RGD loading. The conflicting nature of these results demonstrate the importance of controlling target ligand loading in order to achieve optimal performance for therapeutic and imaging applications. Currently, this agent is being investigated to image expression of αvβ3 in two animal models: (1) in a mouse model of U87MG glioblastoma, and (2) during the re-vascularization process in a mouse model of hind limb ischemia.

Keywords: Nanoparticles, cancer, cardiac imaging

RPY 13 (ORAL)

Molecular signatures based on 2-methoxy phenylpiperazine for neuroreceptor imaging using multimodality approach

Hazari Puja P, Singh N, Raunak, Uppal JK, Chuttani K, Mathur R, Soni S, Mishra AK


Division of Cyclotron and Radiopharmaceutical Sciences, Institute of Nuclear Medicine and Allied Sciences, Brig. S. K. Mazumdar Road, Delhi-110054, India

5-HT1A, the best-characterized subtype of currently known 5-HT receptors, is tightly implicated in the pathogenesis of depression, anxiety, epilepsy and eating disorders. Specific radioligands and positron emission tomography (PET) allow for a quantitative imaging of brain 5-HT1A receptor distribution in living animals and humans. Potent and selective ligands for 5-HT1A receptors labeled with 18F and 11C with high specific activity aids the progress of understanding the pharmacological function of the patient's brain. It is not only desirable to find new compound based on 2-methoxyphenyl piperazine (MPP) selective to 5-HT1A receptors for possible pharmacological activity; such ligands are desired as they may be labeled with different PET/SPECT radioisotopes. We have envisaged to associate 2-methoxyphenyl piperazine with p-nitrophenyl derivative which was then subjected to 18F-fluorination reaction (An efficient one-step approach to label MPP with 18F for PET Imaging). We have developed short-lived 11C (t1/2=20 min) labeled methoxy phenylpiperazine based derivative, [N-methyl-11C]bis{2-(4-(2-methoxy-phenyl)-piperazin-1-yl)ethyl}-amine ([N-methyl-11C]bis-MPP) with high specific activity for PET. The synthesis, characterization and biological evaluation of conjugate the 1-(2-methoxyphenylpiperazine) moiety complexed with paramagnetic metal ion, a fragment of the true 5-HT1A antagonist was carried out and characterized by spectroscopic methods for MRI. Initial studies with primary cultures of rat hippocampal cell lines indicated that the novel derivatives of MPP are highly selective for the serotonin (5-HT1A) receptor. It has significantly higher uptake in the hippocampal region of the brain, where 5-HT 1A receptor density is high.

Keywords: PET, 2-methoxyphenyl piperazine, 5-HT1A receptor

RPY 14 (ORAL)

Development and scintigraphic evaluation of submicron sized dry powder inhalation formulation of fluticasone propionate in healthy human volunteers

Ali Sultana S 1 , Rathore VP, Ali Rashid, Rawat HS, Chopra MK, Ahmad FJ 1 , Khar RK 1 , Mittal G, Bhatnagar A


Division of Nuclear Medicine, Institute of Nuclear Medicine and Allied Sciences (INMAS), Delhi, 1 Lord Shiva College of Pharmacy, Sirsa-125056, 2 Department of Pharmaceutics, Jamia Hamdard, New Delhi, India

Purpose: Objective of the present study concerns formulation and evaluation of submicron sized dry powder inhalation formulation of Fluticasone propionate for the treatment of bronchial asthma, COPD and a new life saving treatment option in restrictive lung diseases such as Interstitial Lung Disease (ILD), toxic and non-cardiogenic pulmonary inflammations or pulmonary edema, which have no effective treatment presently. Materials and Methods: The submicron sized particles were prepared by precipitation method using acetone as solvent and water as antisolvent. Poloxamer F127 was used as stabilizer. Both submicronized and micronized particles were characterized using FTIR, XRD, DSC, SEM and TEM. The mass median aerodynamic diameter (MMAD) of the submicronized and micronized API was calculated using Andersen cascade impactor. The prepared particles and micronized Active Pharmaceutical Ingredient (API) were radiolabeled with Tc99m. Size#3 HPMC capsules were filled with the 12.5 mg radiolabeled blend (100΅g Fluticasone propionate and 12.4mg inhalable lactose) and given to healthy volunteers to assess the comparative pulmonary deposition. Results: The prepared formulation has shown better lung deposition as compared to micronized API. The MMAD of submicronized particles was in the range of 1 - 5 ΅m while the MMAD of micronized API was in the range of 5 - 15΅m. Conclusion: The developed submicron sized dry powder inhalation formulation has better lung deposition as compared to micron sized API and it will become a better treatment option for the bronchial asthma, COPD and ILDs.

Keywords: Casone propionate, dry powder inhaler, mass median aerodynamic diameter, asthma, interstitial lung disease

RPY 15 (POSTER)

Scintigraphic evaluation of floating, gastroretentive formulation of clarithramycin in healthy human volunteers

Ali Raisuddin 1,3 , Bajaj M 2 , Singla YP 2 , Aji Alex MR 1 , Dutta M 1 , Singh 1 Thakuri, Ahmad FJ 3 , Khar RK 3 , Bhatnagar A 1

1Division of Nuclear Medicine, Institute of Nuclear Medicine & Allied Sciences (INMAS), Delhi, 2 Lord Shiva College of Pharmacy, Sirsa-125056, India 3 , Department of Pharmaceutics, Jamia Hamdard, New Delhi, India

Purpose: Objective of the present study concerns formulation and evaluation of oral buoyant effervescent tablets of clarithromycin for prolongation of gastric residence time (GRT) and to enhance eradication of  Helicobacter pylori Scientific Name Search pylori) for longer period of time. Materials and Methods: Clarithromycin (CLA) a macrolide antibiotic was chosen as the candidate drug for its immense potential as an Anti H. pylori agent. HPMC and/or xanthan gum were used as release-retarding polymer(s) whereas sodium bicarbonate (NaHCO 3 ) was utilized as a gas former. The tablets were prepared by wet granulation method. Formulations were evaluated for physicochemical properties, in vitro drug release as well as drug release kinetics and stability studies. In vivo gamma scintigraphic studies were assessed for the optimized buoyant gastroretentive tablets in six healthy human volunteers to study influence of nature of the dosage form i.e. conventional or sustained release gastroretentive tablets and the presence of food in the stomach on intragastric performance of gastroretentive tablets. Result: The fabricated tablets showed acceptable physiochemical properties. Non-fickian release transport was confirmed as the drug release mechanism from the prepared tablets. Optimized tablets composed of HPMC K15M, xanthan gum, and NaHCO 3 were promising systems exhibiting excellent floating properties. The overall performance was found to be highly sustained. Scintigraphic imaging revealed GRT of 320 min or more in fed state on the other hand GRT of 180 min or less in case of unfed state. Conclusion: The developed gastroretentive system has potential to increase efficacy of the therapy and improve patient.

Keywords: Gamma scintigraphy, clarithromycin, gastroretentive, H. pylori

RPY 16 (ORAL)

Synthesis of D-serine based SPECT radiopharma ceutical for tumor imaging: 99mTc-DTPA-bis (D-serine)

Raunak 1 , Hazari Puja P 1 , Chutani K 1 , Uppal JK 1 , Sethi S K 1,2, Srivastava P, Sl Pa 1 , Milton M D 2 , Mishra AK 1

1Division of Cyclotron and Radiopharmaceutical Sciences, Institute of Nuclear Medicine and Allied Sciences, Brig. S. K. Mazumdar Road, Delhi-110054, 2 Department of Chemistry, University of Delhi, Delhi-110054, India

Improvement of scintigraphic tumor imaging is extensively determined by the development of more tumor specific radiopharmaceuticals. Thus, to improve the differential diagnosis, prognosis, planning and monitoring of cancer treatment, several functional pharmaceuticals have been developed. Application of molecular targets for cancer imaging, therapy and prevention using generator-produced isotopes are the major focus of ongoing research projects. Radionuclide imaging modalities (single photon emission computed tomography, SPECT; positron emission tomography, PET) are diagnostic cross-sectional imaging techniques that map the location and concentration of radionuclide-labeled radiotracers. SPECT use radiotracers to image, map and measure target site activities (e.g. angiogenesis, metabolism, apoptosis and proliferation) and they are considered as molecular imaging modalities Polydentate ligands are of particular interest because of their capability to adopt an organized conformation in the complexed form. Entrapment of metal ion into a framework of muldidentate poly (amino carboxylates) such as DTPA covalently attached to amino acids with some metallic radionuclides, especially 111In, and various other lanthanides has been proven to provide thermodynamically stable compounds suitable for clinical trials. In particular, complexation of DTPA moiety with 99mTc showed excellent results as metallopharmaceutical for medical imaging. The work reported in the literature has shown that the DTPA conjugated [DTPA-B-(SLex)A] form stable complexes with lanthanides and transition metals. The main objective of our study was to design and synthesize a novel amino acid derivative based on DTPA, which form stable complexes with most of lanthanides and transition metals in periodic table. Secondly, to introduce a chelating group without compromising the biological integrity of the amino acid for diagnosis of cancer using nuclear medicine and MR techniques. We have synthesized D-Serine-Diethylenetriaminepentaaceticacid-D-serine [DTPA-bis(D-ser)] by conjugating covalently two molecules of D-serine (Ser) to DTPA and was labeled with 99mTc in high radiochemical purity and specific activity. The radiolabeling efficiency was found to be>97% and the stability in serum indicated that 99mTc remained bound to the drug upto 24h. The tumor (EAT cell line) grafted in athymic mice were readily identifiable in the gamma images. The tumor-to-contralateral muscle tissue ratio of 99mTc- DTPA-bis(D-Ser) was found to be 4.9± 1.12% ID/g at 4 h. Biodistribution revealed significant tumor uptake and in the EAT tumor bearing mice.99mTc-DTPA-bis(D-ser) showed excellent tumor targeting and has promising utility as SPECT-radiopharmaceutical for imaging.

Keywords: Tc-DTPA-bis (D-ser), radiopharmaceutical, tumor imaging

RPY 17 (POSTER)

Preparation, characterization and biological evaluation of fac[M(CO) 3 ]+ labeled amino carboxy ligands

Baishya Rinku, Halder KK, Debnath MC


Indian Institute of Chemical Biology, Kolkata, India

Objective: The objective of this study is to radiolabel various amino carboxy based chelating ligands with fac[M(CO)3]+ core, their physicochemical and biological characterization so that they can be used as bifunctional chelators and could be incorporated into biomolecules. Introduction: Amino acids as a class attract considerable physiological interest because of their participation in many vital processes associated with the living system. Some amino acids express in some particular organ like glutamic acid acts as excitatory neurotransmitter in mammalian brain. Histidine, methionine, tryptophan express in the tumor cell. Amino acids also play an important role for development of a new series of chelate complexes of Tc-99m that can direct the biodistribution of the radiotracer for purposes in diagnostic nuclear medicine. Various 99mTc-amino acid chelates based on {Tc(V)O}3+ core were reported from this laboratory some of which exhibited high renal specificity in animals. The structural requirements favouring this biological behaviour coud be the oxotechentium glycine sequence (TcO-NH-CH 2 -COOH) resembling the -CO-glycine sequence of hippurate. In recent years with the development of organometallic chemistry of technetium and rhenium for biological application intensive efforts have been executed on designing of the bifunctional chelator for effective coordination to {M(CO)3}+ core. The suitability and stability of the metal carbonyl core has given rise to a new platform for the preparation of the metal complexes of biologically active peptide in macroscopic quantity using the solid phase synthetic approach. Materials and Methods: We chelated different amino carboxy based ligands with [99mTc(CO)3]+ and [Re(CO)3]+ core. The choice of amino acid was made by taking representative members from various groupings such as mono amino mono carboxylate, mono amino poly caroxylate, poly amino mono carboxylate and sulfur containg amino carboxylates. The chelates were analysed by TLC, HPLC. The stability of the chelates were determined by incubation with saline for 24 hours. Biodistribution studies of fac[99mTc(CO)3]+ amino carboxylates were performed in mice to determine the stability of the chelates under biological condition. Re(CO)3- chelates of three amino acids from (i) diamino mono carboxy, (ii) monoamino dicarboxy and (ii) amino thiol carboxy series were prepared. They were analysed by HPLC. Chemical identity of the chelates were determined by PMR and mass spectral analysis. X-Ray crystallographic studies of Re(CO)3-DAPA was performed. Conclusion: The chelates were pure as identified by the chemical analysis of the Re-congener. They were stable both in vitro and in vivo.

Keywords: fac[M(CO)3]+, amino acid, Re(CO)3-DAPA

RPY 18 (POSTER)

Development and characterization of budesonide pressurized metered dose inhaler using gamma scintigraphy

Sharma BG, Kumar N, Soni S, Rawat HS, Singh T, Mittal G, Nishad DK, Bhatnagar A


Institute of Nuclear Medicine and Allied Sciences (DRDO), Brig. S.K. Mazumdar Road, Timarpur, Delhi-54, India

Budesonide is a glucocorticoid steroid, which is commonly used for the treatment of asthma, non-infectious rhinitis (including hay fever and other allergies), and also used for the treatment and prevention of nasal polyposis. The exact mechanism of action of budesonide is not fully understood yet. However, being a glucocorticosteroid, budesonide has a high local anti-inflammatory effect. Present study was done in order to develop a novel and simple method for radiolabeling of Budesonide to evaluate its stability at RT and physiological condition (serum). The drug was successfully radiolabeled with 99mTc-pertechnetate using stannous salt as a reducing agent. The labeling efficiency was consistently more than 97% as ascertained by ITLC-SG chromatography using 100% acetone as stationary phase. 99mTc-budesonide was found to be fairly stable in vitro as well as in vivo and the stability in serum indicated that 99mTc labeled drug remained bound to the chelate up to 24 hrs. Budesonide pMDI was prepared by filling hydrofluoroalkanes and 99mTc-Budesonide in an aluminum canister under sterilized environment. The in vitro performance of the product, including delivered dose uniformity, dose proportionality was evaluated by radiometry. The respirable fraction and aerodynamic particle size distribution of the 99mTc-Budesonide pMDI-preparation was determined using Anderson cascade Impactor and analyzed by radiometry. The optimized radiolabeled formulation was then evaluated for its clinical efficacy on healthy human volunteers by lung scintigraphy. Budesonide pMDI provided a consistent delivered dose, with a mean value within ± 20% of the label claim. The mass median aerodynamic diameter (MMAD) and geometric standard deviation (GSD) for an aerodynamic particle size distribution determined with an Andersen cascade Impactor (ACI) was 4.73 μ and 1.68 respectively. In vivo internalization of the 99mTc-budesonide was calculated in real time and activity in lungs and body as the internalized fraction in terms of milligrams as well as percentage. Scintigraphy studies showed significant uptake of drug in the lungs. Serial scintigraphic images were taken from 0 to 4 hrs at an interval of 1 hr to estimate bioavailability of drug in the lungs, and consequently respiratory fraction of the drug per mci dose.

Keywords: Budesonide, metered dose inhaler, gamma scintigraphy, Tc99m-Pertechnetate, ACI

RPY 19 (POSTER)

In-vitro and in-vivo evaluation of diclofenac sodium intramuscular injection using gamma scintigraphy

Soni S, Kumar N, Mehra L, Singh T, Mittal G, Nishad DK, Sharma BG, Bhatnagar A


Institute of Nuclear Medicine and Allied Sciences, Brig SK Mazumdar Road, Timarpur, Delhi-1100541, India

Diclofenac is a non-steroidal anti-inflammatory drug (NSAID) which is available as over-the-counter (OTC) medication for the systemic and topical treatment of painful and inflammatory conditions such as arthritis and back pain. This study was undertaken to investigate the distribution and retention of intramuscularly injected diclofenac sodium (DFN) in white NewZealand rabbit using gamma scintigraphy. A new formulation of the nonselective NSAID diclofenac sodium suitable for intramuscular injection has been developed using sesame oil as a vehicle. The hypothesis of present work is to maintain effective concentration of DFN in blood for prolonged time period. A novel method of radiolabeling with 99mTc-pertechnetate was adopted using stannous ions as reducing agent. The radiolabeled product was tested for quality control using ascending instant thin layer chromatography (ITLC) technique. ITLC-SG, (Gelman, USA) and acetone were used as the stationary phase and mobile phase respectively in the chromatographic procedure. In vitro and in vivo stability parameters were evaluated. Biodistribution studies and blood kinetics of 99mTc-DFN was done in balb c mice and white NewZealand rabbit respectively. 99mTc-DFN retention at depot site was evaluated using gamma scintigraphy. 99mTc-DFN, when incubated at 37ºC for 24 hr in normal saline and human serum showed disintigration of only 6.6% and 3.5% respectively, thereby indicating high stability of radiolabeled product. Protein binding studies of 99mTc-DFN shows more than 85% serum protein binding. Blood clearance of radiopharmaceutical in rabbits, exhibited a biphasic exponential pattern in i.v. bolus while in i.m. linear control release pattern were observed up to 24 hrs.

Keywords: 99mTc-DFN, NSAIDs, gamma scintigraphy, i. m. depot, diclofenacy

RPY 20 (POSTER)

99mTc labeling and biological evaluation of a mannose based radioligand for sentinel lymph node imaging

Subramanian Suresh, Pandey U, Samuel G, Venkatesh M


Radiopharmaceuticals Division, Bhabha Atomic Research Centre, Mumbai - 400085, India

Lymphoscintigraphy using 99mTc labeled nanocolloids has been effectively used for determining the status of the sentinel lymph node (SLN) which helps in the further management of primary cancers such as melanoma and breast. The uptake of such nanocolloids at the SLN is entirely due to their particle size and is associated with a number of limitations. Hence, efforts are on for development of radiolabeled receptor-specific agents for SLN detection. Since mannose based macromolecules have been shown to have receptor-mediated uptake in the sentinel node, the aim of the present work is to radiolabel dextran-cysteine-mannose derivative (DCM20) and carry out its biological evaluation for its suitability for use in SLN detection. Materials and Methods: DCM20 conjugate was radiolabeled with 99mTc using 99mTc carbonyl precursor. The radiolabeled complex was characterized by HPLC using a gradient system with acetonitrile/water as solvents as well as by TLC (Methanol: Conc. HCl 95:5). In vivo biological evaluation was carried out in Wistar rat model by injecting ~50-100 ΅L (~200-1000kBq) of the preparation in the footpad. Scintigraphic imaging and biodistribution experiments were performed. Results: The product could be obtained in ~85-90% yield with good in vitro stability. The radiolabeled DCM20 conjugate showed specific and high retention in the SLN (7.56±0.68% Injected dose at 1 h p.i.). The washout from the site of injection was also very high thereby reducing the background and improving the sensitivity of SLN detection. Conclusion: 99mTc labeling and biological evaluation of a mannose based ligand was performed in animal model, which showed very high retention in the SLN with good sensitivity.

Keywords: Lymphoscintigraphy, sentinel node, mannose based macrmolecules

RPY 21 (ORAL)

To study the radiolabeling efficiency and clinical utility of Tc99m- Hmpao0 labeled leukocytes

Saneha, Sarika, Singh B, Mittal BR


Department of Nuclear Medicine, Pgimer0 , Chandigarh-160 012, India

Accurate diagnosis is essential for the effective management of suspected bone infections. Routine imaging techniques have had limited success exhibiting poor soft tissue sensitivity and specificity. So, to diagnose the infection, Tc99m-HMPAO labeled leukocytes is widely used as standard technique, routinely performed in the evaluation of patients with fever of unknown origin and occult infection. The objective of present study was to evaluate the radiolabeling efficiency of leukocytes and to find out the sensitivity and specificity of Tc99m-MDP 3 phase bone scan compared with Tc99m-HMPAO labeled leukocytes to diagnose various types of infection. Patient with suspected bone infection underwent Tc99m MDP 3-phase bone imaging and Tc99m-HMPAO labeled leukocyte imaging on separate occasions. Leukocytes were obtained from 40-50ml of venous blood by centrifugation at 2000 rpm. Freshly eluted TC99m pertechnetate was used to label HMPAO, which in turn was used to tag the leukocytes by adopting the standard technique for labeling leukocytes. In-vitro viability of the cells was demonstrated by Trypan blue dye exclusion method. The labeled cells were resuspended in 2ml normal saline and administered intravenously to the patient. Images were acquired at 60 min., 4 hrs and 24 hrs post-injection. In our study, the labeling efficiency ranged from 39% to 73% with a mean of 59.1%. Tc99m-MDP 3-phase bone scan showed with higher sensitivity and low specificity and thus may be useful as a screening tool but not for the accurate diagnosis of the infection. With the high labeling efficiency of Tc99m-HMPAO leukocytes, this is the reliable tool for the accurate diagnosis of the infection.

Keywords: Radiolabeling efficiency, clinical utility, Tc-99m HMPAO leucocytes

RPY 22 (POSTER)

DTPA: Bis benzimidazole as multi model imaging agent

Srivastava Vikas, Tiwari AK, Sharma H, Sharma R, Mishra AK


Institute of Nuclear Medicine and Allied Sciences (INMAS, DRDO), Delhi, India

The DTPA bis benzimidazole analogue has been tested for radiopharmaceutical efficacy. The radiolebelling was found more then 98% after 8 hrs and blood kinetics was fast. The compound was also tested for optical imaging agent The Eu3+ ion has an absorption band in the visible spectrum (578-582 nm) whose wavelength is very sensitive to even small changes in the coordination environment. Although the intensity of this 7F0 →5D0 transition is low, the bands are relatively narrow, which allows distinguishing different coordination states of the metal. For Eu3+ complexes which have two differently hydrated forms in aqueous solution, one observes two absorption bands belonging to the two species. High-resolution UV-visible spectra were recorded in aqueous solutions which show a temperature invariant absorption with two distinct, temperature-dependent absorption bands. The intensity ratio of these two bands changes with temperature: the band at shorter wavelengths is decreasing very slightly, while that at longer wavelengths is increasing with the temperature. The ratio of the integrals of the two bands is related to the equilibrium constant, and its temperature dependence yields the reaction enthalpy and entropy.

Keywords: DTPA, radiopharmaceutical, optical imaging

RPY 23 (ORAL)

Evaluation of submicrom sized drug particles of salbutamol sulphate by gamma scintigraphy in bronchopulmonary disorders

Rathore VPS, Ali Raisuddin, Chopra MK, Rawat HS, Khanam R 1 , Chugh P 2 , Bhatnagar A 3 , Mittal G, Bhatnagar A


Division of Nuclear Medicine, Institute of Nuclear Medicine and Allied Sciences (INMAS), Delhi, 1 Department of Pharmacology, Jamia Hamdard, New Delhi, 2 Division of Cardiology, Institute of Nuclear Medicine & Allied Sciences (INMAS), Delhi, 3 Rajan Babu TB Hospital, Delhi, India

Purpose: Objective of the present study was to compare the lung deposition pattern of micronized and submicronized salbutamol sulphate nebulization using inhalation therapy for alveolar deposition (ITAD) concept. Materials and Methods: Salbutamol sulphate was radiolabeled with Tc 99m. All the labeling experiments were done at neutral pH. To the labeled drug solution saline was added to make the final concentration 2.5mg/ml. For the deposition of micron sized particles conventional nebulization method was used while in case of submicron particles, ITAD concept was used. In ITAD concept the final volume was made by the addition of ethanolic saline and the particles generated by compressor were passed through large spacers before inhalation by patients. Passing the particles through the large spacer will cause the segregation of particles on the basis of size and mass. Particles which are heavy and with larger diameter will settle down at the bottom of spacer while the lighter and smaller sized particles will cross the spacer and will be available for the inhalation. Result: Scintigraphy images show better lung deposition in case of ITAD concept as compared to traditional /conventional method. Images also insure that the drug gets deposited in the peripheral region by the ITAD concept. Conclusion: It has been concluded that ITAD concept is a better alternative to the conventional nebulization method for the treatment of alveolar pathologies.

Keywords: Radiolabeled salbutamol, inhalation therapy, bronchopulmonary disorders

RPY 24 (POSTER)

Labeling of tirapazamine with 99mTc and its biodistribution in normal rats

Shimpi HH


Radiation Medicine Centre, Bhabha Atomic Research Centre, Parel, Mumbai 400012. India

Tirapazamine (TPZ) is potent antitumor agent currently undergoing phase III clinical trials for certain solid tumors. TPZ is remarkable because it is more toxic in the absence of oxygen than in the presence of oxygen. Although it does not bind to DNA it stimulates oxidative damage to nucleic acid. The aim of this study is to develop non-nitrimidazole hypoxic agent for development of [99mTc]-labeled radiophamaceutical. This compound is synthesized by using reported method Benzofuroxane is reacted with an excess of cyanamide in the presence of an organic base at room temperature. When reaction completes the reaction mixture is treated an organic acid give tirapazamine with high yield. Synthesized TPZ was labeled with 99mTc using SnCl 2 as reducing agent. After the labeling, this [99mTc]-TPZ was passed through 0.2΅m membrane filter and it was seen that there was negligible activity in filtrate since almost all the activity was retained in the filter. This indicated that there was formation of a colloidal complex. To find out when the colloid formation occurs in [99mTc] -TPZ complex, we filtered Sn-TPZ prior to the addition of 99mTc, but no labeling was seen. This implied that the formation of colloidal complex occurs with Sn-TPZ. In order overcome this problem we explored other solvents as well as PBS and citrate buffer saline as the dissolving solvent for TPZ. The citrate buffer saline at pH 5.0 showed good solvent for TPZ labeling with 99mTc, The labeling showed more than 95% labeled complex with ITLC and paper chromatography. The labeled product also found to be stable more than 4 hrs. This 99mTc -TPZ showed no colloidal complex formed, which was filtered even before and after addition of 99mTc. A group of normal animals (Wistar rats) were injected i.v. with [99mTc]-TPZ. At 30min. and 2 h post injection, blood samples were collected by cardiac puncture and animals were sacrificed. The major organs were dissected and counted in animal counter. The pharmacokinetic pattern of the animal study showed faster blood clearance with negligible uptake in brain, thyroid, heart and other major organs including liver and biliary system. This labeled preparation mainly excreted via renal route with about 60-70% activity in urine up to 2hrs. post injection. The accumulation of activity in kidneys was about 10-14%.

Keywords: Radiolabeling, tirapazamine, biodistribution

RPY 25 (ORAL)

Derivatives of serotonergic receptors ligands labeled with SPECT radionuclide for neuronal imaging

Singh Niraj 2 , Hazari Puja P 1 , Uppal JK 1,2 , Chuttani K 1 , Chandra H 2 , Mishra AK 1

1Division of Cyclotron and Radiopharmaceutical Sciences, Institute of Nuclear Medicine and Allied Sciences, Brig. S. K. Mazumdar Road, Delhi-110054, 2 Department of Chemistry, University of Delhi, Delhi-110054, India

Introduction: Serotonergic receptors are associated with a variety of pathophysiology of neuropsychiatric disorders. Serotonergic ligands have remained a very active area in the development of CNS drugs. In search of the ligands that recognize serotonergic receptor we have synthesized derivatives of methoxyphenylpiperazine. Long chain alkylation of methoxyphenylpiperazine was successfully carried out and a series of MPP based precursors were obtained which comprised of hydrocarbon chain of varied length. These derivatives were then conjugated to acyclic chelating system and efficiently labeled with SPECT radionuclide. Materials and Methods: Labeling was performed with high yield (>95%) and radiochemical purity (>98%) using very low ligand concentration. In vivo studies were done on Hela cell lines which overexpress serotonergic receptors. Further studies done includes in vivo distribution and gamma scintigraphy performed in rat and rabbit. Results: All the intermediates and final compounds were characterized by 1H, 13C NMR and Mass Spectroscopy. In vitro binding assays in rat hippocamppal cultures demonstrated the high affinity of complexes for serotonergic receptors. Conclusion: We have optimized the synthesis of 2-methoxyphenylpiperazine based chelating agents. This series of imaging agents holds a promising future in imaging 5-HT receptors for the effective treatment of neuropathological disorders.

Keywords: Serotonergic receptors, neural imaging, radiolabeling

RPY 26 (POSTER)

99m Tc labeled benzimidazole for detecting brain application

Kumar Nitin, Srivastava V, Tiwari AK, Mishra AK


Institute of Nuclear Medicine and Allied Sciences (INMAS), DRDO, Delhi, India

The synthesis and structure-activity relationship of a new class of Benzimidazole/Benzthiazole derivatives with low-nanomolar affinity for the Dopaminergic catachol and high selectivity versus the MAO receptor were found. Based on their chemical structure, four new derivatives which contain atoms to afford future labeling with PET isotopes, were synthesized and evaluated for enzyme activity. All the compound were tested for radiopharmaceutical efficacy. The % radiolabeling efficacy were found more than 95% after 24 hrs. The blood kinetics were found fast in nature which shows that this drug can be utilize for such application in which drug will go in longer time. The % reach in brain were found 3 to 5% which confirms that it can be utilize as brain imaging agent. The Enzyme kinetics of this compound has been studied spectrophotometrically at 25.0ºC and at constant ionic strength of 0.10 mol dm-3. The products were identified by LCESI-MS technique and other spectral studies

Keywords: 99m Tc, benzimidazole, brain imaging

RPY 27 (POSTER)

A rapid test for bacterial endotoxin quantification in 2-[18F]fluoro-2-deoxy-D-glucose by the kinetic chromogenic method

Mitra A, Kulkarni S and Rajan MGR,


Medical Cyclotron Facility, BRIT/BARC, Parel, Mumbai-400012, India

Introduction: The Bacterial Endotoxin (BET) assay of 2-[18F]fluoro-2-deoxy-D-glucose ([18F]FDG), if done prior to release, must be very quick to minimise radioactive decay of [18F]FDG and its specific activity per mL. In order to satisfy harmonized US Pharmacopoeia BET and the FDA guidelines for LAL testing, a quantitative Kinetic Chromogenic test in an automated Portable Test System (PTS) has been developed and patented by Endosafe Inc., USA, to determine BET in ([18F]FDG. The PTS is a handheld fixed wavelength spectrophotometer that utilizes disposable cartridges for accurate and fast BET testing. It also has inbuilt facility of incubation at 37ºC. Here, we present the data of BET analysis done using automated PTS for 15 batches of ([18F]FDG produced at our Medical Cyclotron Facility. Materials and Methods : BET test was carried out by using PTS and polystyrene cartridges containing dry LAL reagents, control standard endotoxin and synthetic chromogenic substrate. The PTS had a sensitivity of 0.05EUmL-1 which is equivalent to the sensitivity of the commonly used Gel Clot assay for BET test. The assay was performed at three different MVD (Maximum Valid Dilution) i.e 1:100, 1:200 and 1:500. It was observed that higher MVD (1:500) for [18F]FDG could be used in this method as compare to used in Gel Clot method (MVD is 1:200 for [18F]FDG). Further, the sensitivity of the lysate used in this method is also high (0.05EUml-1) as compared to Gel Clot method (0.125EUml-1). Samples were also tested at a dilution (less than the MVD) in order to show the consistent elimination of the interfering factors such as pH, ionic strength and high background endotoxin. Results and Discussion: For all three different MVDs, the profile for the % Recovery Positive Product Control (RPPC) and dilution graph factor were similar in all the 15 batches of [18F]FDG. For all the batches analyzed, RPPC which represents the spike recovery, was found to be in the range of 75-150%. The coefficient variant for all the negative control sample was found to be below measurable levels and for positive control was observed to be less than 10%. BETconcentrations for all the 15 batches were below the specified limit described in pharmacopeias. Thus, kinetic chromogenic method using PTS is a rapid, simple and accurate method for quantifying bacterial endotoxin in short lived [18F]FDG and can be introduced in routine biological quality control analysis of samples before release of the product.

Keywords: [18F]FDG, bacterial endotoxin testing, rapid BET

RPY 28 (POSTER)

Calculation of Rƒ value for F-18FDG using ITLC and gamma ray spectrometer

Kumari Kavita, Dhawan DK, Sarika, Singh B


Department of Nuclear Medicine and PET Center, Pgimer0 , Chandigarh, Department of Biophysics, Panjab University, Chandigarh, India

Introduction: Radiopharmaceuticals are essential to the performance of nuclear medicine procedure. Each radiopharmaceutical must pass several quality control tests which includes chemical purity, radionuclide purity, ph, isotonicity, sterility, apyrogenicity and toxicity before dispensing for human administration. F-18 fluorodeoxyglucose (FDG) is a radiopharmaceutical used in positron emission tomography.The most important part in implementing the quality control of 18F-FDG is to determine the percentage of radiochemical purity. We have investigated the Rf value and radiochemical purity 18F-FDG of using ITLC silica gel strips after its synthesis with acetonitrile: H 2 0 (95:5 v/v). Aim: The objective of the present study is to find the Rf value and the radiochemical purity of the F-18FDG just after synthesis using gamma ray spectrometer in our lab. Materials and Methods : 18F-FDG was synthesised using GE TRACERlab MXFDG synthesizer module by the nucleophilic substitution method. The ITLC method for determining the Rf value and radiochemical purity was performed using silica gel ITLC strip (1 cm΄12cm) developed in solvent [acetonitrile: H 2 O (95:5 v/v)] and the counts of the ITLC pieces (1 cm each) were taken using calibrated gamma ray spectrometer with appropriate window settings. A graph was plotted with mean counts vs. piece no. and Rf value and radiochemical purity was calculated using appropriate formulas. Results: The chromatography procedure for calculating the Rf value was performed for 30 days. According to various pharmacopeia, no less than 90% of radioactivity of 18F-FDG injection should locate at Rf ~0.4 of an activated ITLC silica gel plate. In our set up about 98.01% of the 18F-FDG was retained at the Rf value of 0.57. This suggests that the final product (18F-FDG) synthesized at our centre passes the quality control requirement proposed by the various pharmacopeias. The mean Rf values of 18F-FDG injection just after synthesis (within 15 minutes of synthesis of 18F-FDG) was 0.57±0.04. Our value of Rf was slightly higher than what is reported in the literature. The slightly higher value may be due to the different brand of TLC plates and the operation conditions. The mean value of RCP 18F-FDG, just after synthesis, was 98.01±0.91% which is according to what is validated in the various pharmacopeias. The chromatographic procedure's development time was about 15 minutes and as such was rapid for the routine quality control for the concerned radiopharmaceutical. Conclusion: In the present study, the method for determination of Rf value and radiochemical purity of 18F-FDG has been developed successfully.For routine testing, the study demonstrated that the ITLC method using silica gel can be used for the determination of the radiochemical purity of the 18F-FDG with the help of gamma ray spectrometer and should be standardized at the centre.

Keywords: ITLC, Rf value, 18F-FDG, quality control, gamma ray spectrometer




 

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