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Radiolabeling, Stability Studies, and Pharmacokinetic Evaluation of Thulium-170-Labeled Acyclic and Cyclic Polyaminopolyphosphonic Acids.
MedLine Citation:
PMID:  23931111     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Abstract Objective: Thulium-170 [T1/2=128.4 days, Eβ(max)=968 keV, and Eγ=84 keV (3.26%)] could be considered an easily producible and cost-effective alternative to (89)Sr for the preparation of radiopharmaceuticals for palliation of bone pain arising due to skeletal metastases. Multidentate aminomethylene polyphosphonic acids have already been proven to be effective as carrier moieties for developing radiolabeled bone pain palliation agents using lanthanide radionuclides. Therefore, an attempt was made to evaluate the potential of a series of (170)Tm-labeled acyclic (diethylenetriaminepentamethylene phosphonic acid and triethylenetetraminehexamethylene phosphonic acid) and cyclic polyaminopolyphosphonic acids (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetramethylene phosphonic acid [DOTMP] and 1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetramethylene phosphonic acid [CTMP]) toward their use as alternative bone pain palliation agents. Experimental: Thulium-170 was produced by irradiating the natural Tm2O3 target at a thermal neutron flux of 7×10(13) n·cm(-2)·s(-1) for a period of 60 days. All the phosphonic acid ligands were synthesized and characterized in-house. The protocols for radiolabeling the phosphonic acids with (170)Tm were standardized. Biological evaluation of the (170)Tm-labeled phosphonic acids were carried out in normal Wistar rats by biodistribution as well as by scintigraphic studies. Results: Thulium-170 was produced with adequate specific activity (173 Ci/g, 6.41 TBq/g) and high radionuclidic purity (99.62%). All the (170)Tm-labeled phosphonic acids, except (170)Tm-CTMP, were prepared with very high radiochemical purity (>98%) under optimized reaction conditions and exhibited high stability. All the agents showed selective skeletal accumulation with insignificant uptake in other vital organs/tissues and major clearance through renal pathway. These findings were also substantiated by scintigraphic studies. Conclusions: Although all the (170)Tm-labeled phosphonic acids showed significant and selective skeletal accumulation, radiochemical studies indicate that (170)Tm-DOTMP is the best choice for carrying out further evaluation toward its use for clinical applications.
Authors:
Kusum Vats; Tapas Das; Haladhar D Sarma; Sharmila Banerjee; M R A Pillai
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2013-8-9
Journal Detail:
Title:  Cancer biotherapy & radiopharmaceuticals     Volume:  -     ISSN:  1557-8852     ISO Abbreviation:  Cancer Biother. Radiopharm.     Publication Date:  2013 Aug 
Date Detail:
Created Date:  2013-8-12     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9605408     Medline TA:  Cancer Biother Radiopharm     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Affiliation:
1 Radiopharmaceuticals Division, Bhabha Atomic Research Centre , Mumbai, India .
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