Preparation and quality control of [177]Lu-chitosan for radiosynovectomy

Rheumatoid arthritis [RA] is the most common autoimmune disease, leading to the destruction of the joints and causing pain, disability, and immobility in the patients. Radiosynovectomy [RSV] has been applied as an effective treatment for the patients with resistant synovitis after failure of long-term pharmacotherapy and intra-articular steroid injection for more than 50 years. Several radiopharmaceuticals have been developed for RSV so far, but still development of new radiophamaceuticals is of crucial interest. In this research, the [177]Lu-chitosan complex [[177]Lu-CHITO] was introduced as a new agent for RSV. [177]Lu was produced by irradiation of a natural Lu2O3 target at a thermal neutron flux of approximately 4 x 10[13] n/cm[2]s. [177]Lu-CHITO was prepared in the diluted acetic acid solution. The radiochemical yield was checked by ITLC method. The biodistribution of the complex was investigated by intra-articular injection to rabbits' and rats' knee joints. The leakage of injected dose from the injection site in the rabbit organs was investigated using SPECT imaging up to 48 hours. [177]Lu was prepared with a specific activity of 2.6-3 GBq.mg[-1] and radionuclide purity of 99.98%. [177]Lu-CHITO was prepared successfully with high radiochemical purity [95%] and specific activity of 888 TBq/mmol. Both the biodistribution data in rats and SPECT imaging of the rabbit showed that there was no significant leakage of the injected activity even after 192 h. Considering all of the excellent features of the complex, this radiopharmaceutical can be used for effective management of synovial inflammation

Radiosynthesis of [191]Os-2-acetylpyridine thiosemicarbazone complex, as an in vivo therapeutic radionuclide generator

Due to the anti-proliferative properties of platinum group-thiosemicarbazone complexes, the production of [191]Os-labeled 2-acetyl pyridine 4-N-methylthiosemicarbazone [[191]Os-APMTS] was investigated. [[191]Osmium [T[1/2]= 15.4d] was produced via the [190]Os[n,gamma][191]Os nuclear reaction using enriched target irradiated with thermal neutrons. Reaction of in-house synthesized 2-acetylpyridine thiosemicarbazone [APMTS] with [191]Os yielded [[191]Os]APMTS checked by ITLC followed by stability, partition co-efficient and biodistribution determination. Following synthesis and spectroscopic determination of the ligand [>99% chemical purity], the complex was prepared with a radiochemical purity of more than 95% [RTLC] and specific activity of 21.5 GB/mM and was stable in the formulation and presence of human serum at 37[degree sign]C for up to 48h. The partition coefficient was determined [log P. 1.23]. The biodistribution study up to 4 days demonstrated significant tissue uptake differences in the bone, blood, heart and thyroid. This is the first Os-191 labeled thiosemicarbazone designed as an in-vivo therapeutic radionuclide generator. Further investigation is ongoing on the evaluation of the complex in tumor bearing animals

Optimization condition in labeling of ofloxacin with [99m]Tc and its biological evaluation in Staphylococcus aureus and Escherichia coli for infection imaging

The use of radiopharmaceuticals is a powerful tool in the management of patients with infectious or inflammatory diseases in nuclear medicine. In this study ofloxacin as a second-generation fluoroquinolone is used to design a desired infection imaging agent after labeling with [99m]Tc via direct labeling. Ofloxacin was radiolabeled with [99m]Tc using different concentrations of ligand, stannous chloride, sodium pertechnetate and at different pH. Then labeling yield, stability in saline and serum, lipophilicity, binding with Staphylococcus aureus and Escherichia coli and biodistribution in infected mice for labeled compound were studied. The final complex was characterized by TLC and HPLC and radiochemical purity of >90% was obtained when 1.5 mg ofloxacin in presence of 75 micro g SnCl2 was labeled with 370 MBq sodium pertechnetate. The complex showed specific binding to Staphylococcus aureus and Escherichia coli. Biodistribution results showed that radioligand had high affinity in the infected site in mice. The uptake for Staphylococcus aureus induced infections [T/NT = 2.33 +/- 0.17 at 1 h post injection] was higher than that was for Escherichia coli [T/NT = 1.96 +/- 0.13 at 1 h post injection]. This complex may lead to further development of a radiotracer for imaging of infections induced by grampositive or gram-negative bacteria

Preparation and quality control of scandium-46 bleomycin as a possible therapeutic agent

Due to interesting therapeutic properties of [46]Sc and antineoblastic antibiotic, bleomycin [BLM], 46Scbleomycin [[46]Sc-BLM] was developed as a possible therapeutic compound. In this work, Sc-46 chloride was obtained by thermal neutron flux [4 × 10[13] n.cm[-2].s[-1]] of natural metallic scandium sample followed by dissolution in acidic media as a substitute for [47]Sc in radiolabeling studies which was further used for labeling of bleomycin [BLM] followed by stability studies as well as biodistribution in wild-type rats. Sc-46 was obtained in high radiochemical purity [ITLC, >99%, two systems] as well as acceptable specific activity. At optimized conditions a radiochemical purity of 98% was obtained for [46]Sc-BLM shown by ITLC [Specific activity, 740 GBq/mmole]. The accumulation of the radiolabeled compound in lungs, liver and spleen demonstrates a similar pattern to the other radiolabeled bleomycins. Sc-BLM is a possible therapeutic agent in human malignancies and the efficacy of the compound should be tested in various tumor-bearing models

Production of holmium-166 DOTMP: a promising agent for bone marrow ablation in hematologic malignancies

Therapeutic radiopharmaceuticals are radiolabeled molecules to deliver sufficient doses of ionizing radiation to specific disease sites such as bone metastases, brain and liver tumors and bone marrows malignancies including multiple myeloma. Among some therapeutic radiopharmaceuticals, 166Ho-1, 4, 7, 10-tetraazacyclo dodecane-1,4,7,10 tetraethylene phosphonic acid [166Ho-DOTMP] is used for delivering high doses to bone marrow. In this research production, quality control, pharmacokinetics and biodistribution studies of 166Ho-DOTMP with respect to its radiochemical and in vivo biological characteristics have been presented. Holmium-166 was produced by irradiation of holmium oxide [Ho2O3, purity>99.8%] at a thermal neutron flux. 166Ho-DOTMP complex was obtained in very high yields [radiochemical purity>99%] under the reaction conditions employed. Radiochemical purity and the stability of the 166Ho-DOTMP complex in human serum were assayed. Wild type rats were used for biodistribution and imaging studies of this agent. 166Ho produced by irradiation of holmium-165 oxide demonstrated high radionuclide purity. 166Ho-DOTMP was obtained in very high yield [radiochemical purity>99%] and the complex exhibited excellent in vitro stability at pH-7 when stored at room temperature and human serum. Biodistribution studies in rats showed favorable selective skeletal uptake with rapid clearance from blood along with insignificant accumulation of activity in other non-target organs. The scintigraphic image recorded in rat at 3 h after the injection of the 166Ho-DOTMP radiopharmaceutical revealed that 166Ho-DOTMP rapidly accumulated in skeleton especially in the thigh bones. Biodistribution, stability, imaging and pharmacokinetics studies of 166Ho-DOTMP radiopharmaceutical in this research showed favorable features such as; rapid and selective skeletal uptake, fast clearance from blood and almost no uptake in any other major organs. Our research demonstrated that 166Ho-DOTMP has promising features suggesting good potential for efficient use of this radiopharmaceutical for bone marrow ablation in different hematologic malignancies including multiple myeloma

Preparation and evaluation of 67Ga-DOTA-Bombesin [7-14] as a tumor scintigraphic agent

Bombesin is a 14-aminoacid peptide isolated from frog skin. The mammalian counterparts of the frog peptide are neuromedin B [NMB] and gastrin-releasing peptide [GRP]. Bombesin [BBN] is a peptide showing high affinity for the gastrin releasing peptide receptor [GRPr]. Prostate, small cell lung cancer, breast, gastric, and colon cancers are known to over express receptors to bombesin [BBN] and gastrin releasing peptide [GRP]. In this study a new 67Ga radiolabeled BBN analogue evaluated based upon the bifunctional chelating ligand DOTA [1, 4, 7, 10-tetraazacyclododecane-1, 4, 7, 10-tetraacetic acid] that can be used as a tool for diagnosis of GRP receptor-positive tumors. DOTA-BBN [7-14] NH2 was synthesized using a standard Fmoc strategy. Labeling with 67Ga was performed at 95°C for 30 minutes in ammonium acetate buffer [pH=4.8]. Radiochemical analysis involved ITLC and HPLC methods. The stability of radiopeptide was examined in the presence of human serum at 37°C up to 24 hours. The receptor-bound internalization and externalization rates were studied in GRP receptor expressing PC-3 cells. Biodistribution of radiopeptide was studied in nude mice bearing PC-3 tumor. Labeling yield of>90% was obtained corresponding to a specific activity of=2.48 MBq/nmol. Peptide conjugate showed good stability in the presence of human serum. The radioligand showed a good and specific internalization into PC-3 cells [14.13 +/- 0.61% at 4 h]. In animal biodistribution studies, a receptor-specific uptake of radioactivity was observed in GRP-receptor-positive organs. After 4 h, uptake in mouse pancreas was 1.08 +/- 0.29% ID/g [percentage of injected dose per gram of tissue]. These data show that [67Ga]-DOTA-Bombesin [7-14] NH2 is a specific radioligand for gastrin-releasing peptide receptor positive tumors

Development of sm-153 chitosan for radiosynovectomy

Developing new radiosynovectomy agents is of great importance due to the aging of human populations around the world and increasing the incidence of inflammatory diseases. In this work, Sm-153 chitosan agent was developed for the first time in our country and preparation and quality control of the compound is described. Sm-153 chloride was obtained by thermal neutron flux [4-5 x 10[13] n.cm [-2]. S[-1] of natural Sm[2]O[3] sample, dissolved in acidic media. [153] Sm-samarium chloride [370 MBq] was used in preparation of [153] Sm-chitosan complex followed by quality control using MeOH: H[2]O: acetic acid [4: 4: 2] as mobile phase. The complex stability and viscosity were checked in the final solution up to 2 days. The complex solution and [153]Sm[3+] [80 micro Ci/100 micro l] were injected intra-articularly into male rat knee joint followed by scarification studies 6d post injection. Sm-153 chitosan was prepared successfully with high radiochemical purity [>99%, ITLC] at room temperature after 10-30 min followed by autoclave sterilization. The complex was stable at room temperature and 37 [degree sign] C up to 2 days. No significant leackage of dose from injection site and its distribution in organs were observed up to 6 days for [153] Sm-chitosan. Approximately, more than 90% of injected dose remained in injection site after 6d. The complex is a dedicated agent for radiosynovectomy. The experience from this study would lead to the development of more sophisticated radiosynovectomy radiopharmaceuticals for human use in the country

Production and quality control of [166]Ho-chitosan for therapeutic applications

In this research, [[166]Ho]Holmium chitosan complex production is described in details, followed by determination of complex radiochemical purity, stability and biodistribution [after intra-articular injection] in wild-type male rats. Finally a Ho-166 based chitosan kit for ultimate radiosynovectomy as well as radiotherapy applications was developed. [166]Ho-chitosan complex was prepared using chitosan concentrations and [166]HoCl[3] followed by intra-articular injection and biodistribution studies in wild-type rats including and excluding injected knee. The [[166]Ho]Holmium chitosan complex was prepared with high radiochemical yield [>95%] in the optimized condition [35mg/3ml of chitosan in%1 AcOH, pH. 3, >98%, ITLC] was injected to wild-type rats followed by the biodistribution studies of the compound among the tissues excluding the injected knee data. Intra-articular injection of [[166]Ho]holmium chitosan complex to male wild-type rats and investigation of leakage of activity in the body showed that most of injected dose has remained in injection site 144 h after injection. Successful development and formulation of [166]Ho-chitosan kit is described. This kit has the potential for use in clinical setting namely for radiosynovectomy and cancer radiochemotherapy

Synthesis and evaluation of a new radiolabeled bombesin analogue for diagnosis of GRP receptor expressing tumors

Bombesin [BN], a 14-amino acid neuropeptide, shows high affinity for the human GRP [gastrin releasing peptide] receptors, which are overexpressed by a variety of cancers, including prostate, breast, pancreas, gastrointestinal, and small cell lung cancer. Aim was to prepare [6-hydrazinopyridine-3-carboxylic acid [HYNIC[0], D-Tyr[6], D-Trp[8]] - BN [6-14] NH[2] that could be easily labeled with[99m]Tc and evaluation of its potential as an imaging agent. Synthesis of the peptide amide was carried out onto Rink Amide MB HA [4-Methylbenzhydrylamine] resin. A bifunctional chelating agent [BFCA] was attached to the N terminal peptide in solid-phase. [99m]Tc labeling was performed by addition of sodium pertechnetate to solution that include [HYNIC[0], D-Tyr[6], D-Trp[8]] Bombesin [6-14] NH[2], tricine, ethylenediamine-N,N'-diaeetic acid [EDDA] and SnCl[2]. Radiochemical evaluation was carried out by reverse phase high-performance liquid chromatography [HPLC] and instant thin layer chromatography [ITLC]. In- vitro internalization was tested using human prostate cancer cells [PC-3] with blocked and non-blocked receptors. Biodistribution was determined in rats. [99m]Tc/tricine/EDDA-HYNIC[0], D-Tyr[6], D-Trp[8]] bombesin [6-14] NH[2] was obtained with radiochemical purities >98%. Results of in-vitro studies demonstrated a high stability in serum and suitable internalization. Biodistribution data showed a rapid blood clearance, with renal excretion and specific binding towards GRP receptor-positive tissues such as pancreas. In this study, labeling of this novel conjugate with [99m] Tc easily was performed using coligand. The prepared [99m]Tc-HYNIC-BN conjugate has promising characteristics for the diagnosis of malignant tumors

Synthesis, labeling and quality control of a new neuropeptide Y analogue for diagnosis of breast tumors

Over expression of selected peptide receptors in human tumors has been shown to represent clinically relevant targets for cancer diagnosis and therapy. The aim of this work was to investigate Neuropeptide Y [NPY] as a new radiopharmaceutical for diagnosis of breast cancer. A neuropeptide Y analogues with Y[1] receptor preference and agonistic properties was synthesized by solid phase method. After conjugation with diethylenetriaminepentaacetic acid [DTPA] labeling with [111]In was performed. For labeled peptide, yield of labeling, stability in human serum, receptor binding in cell surface with internalization in SK-N-MC cells, and biodistribution in normal rat were determined. Peptide was synthesized and labeled with more than 95% purity. Radiolabeled peptide was stable in human serum and specifically binds and internalized in the cells with Y1 receptor [4h = 22%]. A rapid clearance from blood pool and urinary with hepatobiliary excretion were observed. Our results showed that this peptide can be considered as a candidate for diagnosis of breast tumors

New peptide based freeze-dried kit [99m] Tc-HYNIC]-UBI 29-41 as a human specific infection imaging agent

Ubiquicidin 29-41 [UBI] is a fragment of the cationic antimicrobial peptide that is present in various species including humans. The purpose of this study was to investigate radiochemical and biological characteristics of [6-hydrazinopyridine-3-carboxylic acid [HYNIC]]-UBI 29-41 designed for the labeling with 99mTc using tricine as coligand. Synthesis was preformed on a solid phase using a standard Fmoc strategy and HYNIC precursor coupled at the N-terminus. Purified peptide conjugate was labeled with 99mTc at 100°C for 10 min. Radiochemical analysis involved ITLC and high-performance liquid chromatography methods. Peptide conjugate stability and affinity to human serum was challenged for 24 hours and its in vitro binding to bacteria was assessed. Biodistribution and accumulation of radiopeptide in staphylococcus aureus infected mice were studied using scintigraphy and ex vivo counting. Radiolabeling was performed at high specific activities, and radiochemical purity was >95%. The stability of radiolabeled peptide in human serum was excellent. In vitro studies showed 70% of radioactivity was bound to bacteria. After injection into mice with a bacterial infection, removing from the circulation occurred mainly by renal clearance and site of infection was rapidly detected within 30 min. Target to nontarget muscle ratio was 2.099 +/- 0.05% at 30 min post injection. [99mTc-HYNIC]-UBI 29-41 showed favorable radiochemical and biological characteristics which permitted detection of the infection with optimal visualization within 30 min