title: Preliminary dosimetry of (166)Ho-propylene di-amino tetra (methy1enephosphonicacid) for human based on biodistribution data in rats.
abstract: BACKGROUND
  Nowadays, radionuclides with high β- particle energies such as (166)Ho are recommended for bone marrow ablation in patients with multiple myeloma. The addition of skeletal targeted radiotherapy to the patients can improve the response rate in phase I and II trials, with promising long-term survival data.
  
  
  OBJECTIVE
  In this work, the absorbed dose to each organ of human for (166)Ho-propylene di-amino tetra methy1enephosphonicacid (PDTMP) was evaluated based on biodistribution studies in rats and was compared with (166)Ho-tetraazacyclododecane tetramethylene-phosphonate (DOTMP) as the only clinically used Ho-166 bone marrow ablative agent.
  
  
  METHODS
  In this work, the accumulated activity in animals was extrapolated to the accumulated activity in humans by mass extrapolation method. The absorbed dose to each organ of human for (166)Ho-PDTMP was evaluated by medical internal radiation dose method.
  
  
  METHODS
  In this study, 166 Ho-PDTMP complex was prepared successfully using an in-house synthesized PDTMP ligand and (166)HoCl 3. Radiochemical purity of (166)Ho-PDTMP was checked by instant thin layer chromatography (>99%). The biodistribution of (166)Ho-PDTMP in wild-type rats was checked in animal tissues up to 48 h.
  
  
  METHODS
  All values were expressed as mean ± standard deviation, and the data were compared using Student's t-test. Statistical significance was defined as P < 0.05.
  
  
  RESULTS
  The highest absorbed dose for this complex is observed in red marrow with 0.691 mSv/MBq. (166)Ho-PDTMP demonstrated a higher red marrow: Non target organ uptake ratio compared to (166)Ho-DOTMP.
  
  
  CONCLUSIONS
  The results showed that 166 Ho-PDTMP has considerable characteristics compared to (166)Ho-DOTMP and therefore can be a good candidate for bone marrow ablation.
authors.forename: Samaneh
authors.initials: S
authors.lastname: Zolghadri
authors.affiliation: Department of Nuclear Fuel Cycle, Nuclear Science and Technology Research Institute, Tehran 14155-1339, Iran.
authors.forename: Hassan
authors.initials: H
authors.lastname: Yousefnia
authors.forename: Amir R
authors.initials: AR
authors.lastname: Jalilian
authors.forename: Zahra
authors.initials: Z
authors.lastname: Shiri-Yekta
authors.forename: Mohammad Ghannadi-
authors.initials: MG
authors.lastname: Maragheh
mesh_terms: D000475:Alkenes / Q000737:chemistry*; D000818:Animals; D056831:Coordination Complexes / Q000493:pharmacokinetics*; D006801:Humans; D009942:Organometallic Compounds / Q000008:administration & dosage / Q000493:pharmacokinetics*; D063065:Organophosphonates / Q000493:pharmacokinetics*; D009943:Organophosphorus Compounds / Q000008:administration & dosage / Q000493:pharmacokinetics*; D019275:Radiopharmaceuticals / Q000008:administration & dosage / Q000493:pharmacokinetics*; D051381:Rats; D014018:Tissue Distribution
chemical_list: C000612077:(166)Ho-propylene di-amino tetra(methylenephosphonic acid); D000475:Alkenes; D056831:Coordination Complexes; D009942:Organometallic Compounds; D063065:Organophosphonates; D009943:Organophosphorus Compounds; D019275:Radiopharmaceuticals; C093387:holmium-1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetrakis(methylenephosphonic acid); C013658:propylene