Development of 186/188Re-Chitosan as an Effective Therapeutic Agent for Rheumatoid Arthritis

Background: Rheumatoid arthritis (RA) is an inflammatory chronic disease characterized by inflammation, pain, swelling and disability and radiosynovectomy is one of the disease treatment lines. In this study, the possibility of providing rhenium-186/rhenium-188 chitosan radiopharmaceuticals, optimization of conditions for their production and bio-distribution. Objective: In order to build perrhenic acid for labeling, natural rhenium was exposed to radiation. Radionuclidic and radiochemical purities of (186/188Re)-NaReO4 were examined by gamma spectroscopy and paper chromatography methods, respectively. Methods: Labeling of chitosan with rhenium was done in different acidic situations. The radiochemical purity 186/188Re-chitosan was applied by radio thin layer chromatography (RTLC). Lastly, the bio-distribution of the radiolabeled chitosan was studied in various organs after intra articular injection of the complex to lab rats. Gamma spectrometry confirmed the high rhenium radionuclidic purity. Chromatography results showed that perrhenic acid was produced with purity greater than 97% and rhenium chitosan labeling was done over 98% in pH = 3. Dissection results showed high bio-distribution of 186/188Re-chitosan after injection into the joint with no leakage to surrounding organs. Conclusion: According to the results, there is a possibility of labeling rhenium with chitosan in very high radiochemical purity. Regarding the high retention of these radiopharmaceuticals in joints with no leakage to surrounding organs, 186/188Re-chitosan can be applied as new radiosynovectomy drugs for rheumatoid arthritis treatment.

Rhenium(VII) Compounds as Inorganic Precursors for the Synthesis of Organic Reaction Catalysts

Rhenium is an element that exhibits a broad range of oxidation states. Synthesis paths of selected rhenium compounds in its seventh oxidation state, which are common precursors for organic reaction catalysts, were presented in this paper. Production technologies for copper perrhenate, aluminum perrhenate as well as the ammonia complex of cobalt perrhenate, are thoroughly described. An ion exchange method, based on Al or Cu metal ion sorption and subsequent elution by aqueous perrhenic acid solutions, was used to obtain perrhenates. The produced solutions were neutralized to afford the targeted aluminum perrhenate and copper perrhenate products in high purity. The developed technologies allow one to manage the wastes from the production of these perrhenates as most streams were recycled. Hexaamminecobalt(III) perrhenate was produced by a newly developed method enabling us to produce a high purity compound in a reaction of spent hexaamminecobalt(III) chloride solution with a perrhenic acid. All prepared compounds are the basis for precursor preparation in organic catalysis.

Technology to Produce High-Purity Anhydrous Rubidium Perrhenate on an Industrial Scale

Technology used to produce high purity anhydrous rubidium perrhenate on an industrial scale from high purity perrhenic acid and rubidium nitrate by the ion-exchange method is described in this paper. This material is dedicated to catalyst preparation, therefore, strict purity requirements have to be fulfilled. These are satisfied by combining rubidium ion sorption on an ion exchange column and the subsequent elution of the high purity perrhenic acid solution, followed by crystallization, evaporation, purification, and drying. In the current study, rubidium and rhenium contents were found to be 22.5 wt.% and 55.4 wt.%, respectively, while contaminations were as follows: <2 ppm As, <2 ppm Bi, <5 ppm Ca, <5 ppm Cu, <3 ppm Fe, <10 ppm K, <3 ppm Mg, <5 ppm Mo, <2 ppm Na, <5 ppm Pb, and <3 ppm Zn.