Stabilization of Tc-99m radiopharmaceuticals by chemical additives

The reliability and applicability of the preparation of the three, for nuclear medicine very important, Tc-99m-radiopharmaceuticals from the inactive (technetium-cold) kit solutions were tested. Each examined commercial kit was dissolved in saline (0.9 % NaCl). The conditions of the storage of the inactive kit solutions till labeling were examined. The main problem is the stablity of the reductant stannous ions which is very difficult to predict. To stabilize and ensure a good quality of the labeled radiopharmaceuticals, ascorbic or gentisic acid were added. It was found that the best results were obtained by keeping the samples frozen at-20 degreesC. Both stabilizers can be used but for an effective protection much lower concentrations of ascorbic acid are needed. Its concentrations of 12-60 mug/ml of the kit, stabilized dimercaptosuccinate (DMS) and pyrophosphate (PyP) for about 7-8 days. The solution of 2,3-dicarboxypropane- 1,1-diphosphonate (DPD) was found to be stable even without the stabilizer. This could be attributed probably to the chemical nature of this complex. However, in routine praxis the applied procedure demands great care and personel very experienced in radiopharmacy

Influence of magnetic field on the reduction of 4,8-diaza-3,6,6,9-tetramethyl undecane-3,8-diene2,10-dione dioxime

The influence of the magnetic field with the magnetic induction up to 1,35T on the reduction of 4,8-diaza-3,6,6,9-tetramethylundecane-3,8-diene-2,10-dione dioxime (DI) in anhydrous protic solvents (anhydrous ethanol and 2-propanol) was defined. As the reductants NaBH4 and KBH4 were usedPhysical chemistry 2004 : 7th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 21-23 September 200

Radionuklidni generatori za dobijanje tehnecijuma-99m i renijuma-188

The paper deals with production and application of open radioactive sources in modern diagnostic and therapeutic nuclear medicine. In principle, besides adequate physical, chemical and biological properties a reliable route for the routine production of both radionuclide and radiopharmaceutical should be on disposal. The favorite route are radionuclidic generators as they enable simple production of shorter-lived radionuclides at relatively low costs. The main radionuclide in diagnosis is technetium-99m. Its advantages are favorable nuclear properties, availability of large activities of high quality 99m Tc at reasonable prices by using (n,f)99Mo/ 99m Tc generators and versatile chemistry. It is used in the investigation of practically all organs and tissues in the human body. Among the beta- emitters the radionuclides of rhenium have been recently proposed as suitable candidates for therapeutic applications. The most important is 188Re which is obtained from 188W/ 188Re generator. Some of the important radiopharmaceuticals labeled with rhenium radionuclides used for certain specific indications are also shown. The activities performed in the Laboratory for Radioisotopes (Vinča Institute of Nuclear Sciences) are also enclosed.Prikazani su neki od najvažnijih aspekata proizvodnje i primene otvorenih izvora radioaktivnog zračenja u dijagnostičkoj i terapijskoj nuklearnoj medicini. Pored fizičkih, bitne su i hemijske i biohemijske osobine datog radionuklida odnosno radiofarmaceutika. Uslov za redovnu primenu su i dostupnost, kvalitet i cena. Radionuklidni generatori predstavljaju vrlo pogodan izvor dobijanja radionuklida kraćih vremena poluraspada. Najvažniji dijagnostički radionuklid je 99m Tc. Odlične fizičke osobine, visok kvalitet i laka dostupnost po prihvatljivim cenama korišćenjem molibden-99/tehnecijum- 99m generatora i razvijena hemija doveli su do toga da ovaj radionuklid postane praktično nezamenjiv u ispitivanju skoro svih organa i tkiva u ljudskom organizmu. Dati su savremeni trendovi u razvoju proizvodnje radionuklida i radiofarmaceutika za primenu u terapijske svrhe. Prikazani su načini dobijanja radionuklida renijuma (186Re i 188Re) sa posebnim naglaskom na 188W/ 188Re generatoru. Dati su hemijski oblici i indikacije za primenu nekih radioaktivnih lekova obeleženih ovim radionuklidima. Prikazana su istraživanja sprovedena u Laboratoriji za radioizotope (Institut za nuklearne nauke «Vinča»)

Preparation of concentrated rhenium solutions

The conditions of the desorption of rhenium from the anion exchange resin Dowex 1×8 by nitric acid were determined. The solution (5×10-3 mol/dm3 Re in 0.15 mol/dm3 NaCl) was passed through the column containing 0.1 g of the resin. The total sorbed amount of rhenium was 200 mg/g of the resin. It was then eluted by nitric acid in the concentration range of 0.16-7.2 mol/dm3 . The most favourable elution profile was found with 3.0 mol/dm3 HNO3. Over 77% of the total rhenium was desorbed with 5 ml of this eluence. Over 95% of the sorbed rhenium was recovered by using 20 ml of nitric acid in the concentration range of 0.9-7.2 mol/dm3 .Physical chemistry 2006 : 8th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 26-29 September 200

Technetium-99m in Production and Use

Several types of generators have been developed for the production of (99m)Tc. Due to its excelent performances, the chromatographic type, based on the fission-produced (99)Mo sorbed in alumina, is predominant. Technetium-99m is obtained in the form of sodium pertechnetate-(99m)Tc. However, due to the known disadvantages of the production of (n, f)(99)Mo, attempts are made to avoid uranium fission. The technologies based on (n, gamma)(99)Mo (sublimation, extraction, gel) are, with the exception of the gel generator, of limited importance. Certain nuclear reactions in cyclotrons can produce (99)Mo (or directly (99m)Tc) but the obtained results are still not satisfying. Technetium-99m is used in the form of radiopharmaceuticals which are prepared by addition of (99m)Tc-eluate to the inactive components comprised in the cold kits. The chromatographic (n, f)(99)Mo/(99m)Tc generator and several (99m)Tc-radiopharmaceuticals have been developed and are regularly produced in the Vinca Institute of Nuclear Sciences (Laboratory for Radioisotopes)

Separation of rhenium (VIII) from tungsten (VI)

Examined were the conditions for an effective separation of tungsten(VI) and rhenium(VII) on alumina if the solution of 0.20 mol dm-3 NaCl, pH=2-6, is used as the aqueous phase. Under the given experimental conditions alumina was found to be much better adsorbent for tungsten than for rhenium. The breakthrough and saturation capacities of alumina at pH = 2 are 24 and 78 mg W/g Al2O3, respectively. With the increase of pH these values decrease. So, at pH = 6 they are only 4 and 13 mg W/g Al2O3, respectively. The elution volume for rhenium for the given column dimensions and the quantity of the adsorbent, is about 16 ml. These results were confirmed by the experiments of the radiochemical separations. Tungsten-187 remains firmly bound to alumina. The radionuclidic purity of the eluted 186,188 Re at pH = 2 is very high.Physical chemistry 2004 : 7th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 21-23 September 200

Sorption of rhenium on alumina under dynamic conditions

The sorption of perrhenate anion on alumina from aqueous solutions of sodium chloride was investigated under dynamic conditions. The initial concentrations of rhenium were in the range of 2.7 x 10(-2)-2.7 mmol/dM(3). The breakthrough curves as the function of Re and NaCl concentrations (0. 12-0.20 mol/dm(3)), pH 2-6 and flow rate 3-10 ml/min were determined. According to the experimental results, it was concluded that the breakthrough capacities, the capacities at c/c(0) = 0.5, the total column capacities and the utilization degrees (column efficiency) increase with increasing Re and NaCl concentrations and decreasing pH. The optimal flow rate was found to be 3 ml/min. At pH 2 and c(0) = 2.7 mmol Re/dm(3), the total capacity was found to be Q(0.9) (max) = 2.1 x 10(-2) mmol Re/g Al2O3. The data for perrhenate anions fit with a Henry-type isotherm. It was found that, under the above mentioned conditions, the value of the Henry constant K-H was 7.8 x 10(-3) dm(3)/g and the Gibbs energy change, Delta G was -0.5 kJ/mol

Effect of experimental conditions on the in vitro stability of Tc-99m(Sn)-pyrophosphate

The in vitro stability of Tc-99m(Sn)-PyP as a function of experimental conditions of the preparation of the kit and time elapsed after labeling has been tested. The preparation was protected by using nitrogen-purged reactant solutions and kit vials and by ascorbic acid. The samples under nitrogen are stable for 6 h when the content of Tc-99m-pertechnetate raises to 5%. The best stability was achieved by addition of 5 mu g of ascorbic acid per ml of the kit (content of Tc-99m-pertechnetate about 0.5%). To accelerate the decomposition, exogenous hydrogen peroxide was used. In this case it was found that the presence of 10 mu g of ascorbic acid inhibits the effect both of oxygen and peroxide (6 mu g H2O2/ml of the kit). Radiochemically purity of 99mTc(Sn)-PyP remains practically unchanged for 6 h (content of Tc-99m-pertechnetate about 0.5%)