title: In vivo evaluation of 99mTc-DTPA and 99mTc-sulphur colloid as tracers in colonic drug delivery systems using gamma scintigraphy in volunteers.
abstract: OBJECTIVE
  The suitability of 99mTc-diethylenetriaminepenta- acetic acid (DTPA) and 99mTc-sulphur colloid (99mTc-SC) as tracers in gamma scintigraphy for the evaluation of colon-specific drug delivery systems was assessed in healthy volunteers.
  
  
  METHODS
  Sodium chloride core tablets containing either 99mTc-DTPA or 99mTc-SC were prepared and compression coated with two different quantities of guar gum. The compression-coated tablets were subjected to gamma scintigraphic studies for colonic drug delivery in healthy human volunteers.
  
  
  RESULTS
  The tablets containing 99mTc-DTPA did not release the tracer in stomach and small intestine, and on entering the colon disintegrated completely whereas the tablets containing 99mTc-SC remained intact in stomach, small intestine and in colon as well. The study showed that DTPA is a suitable tagging agent for 99mTc in the evaluation of guar gum based colonic drug delivery systems containing water-soluble drugs.
  
  
  CONCLUSIONS
  In the present investigation guar gum was applied externally as a compression coat over the radiolabelled core. Since the core consisted of water-soluble material (sodium chloride), it is possible that the release of the tracer from the 99mTc-DTPA containing formulations is a combined effect of enzymatic action and diffusion of the salt. The failure of disintegration of 99mTc-SC containing formulations might be due to its interference with the disintegration or the part diffusion observed with 99mTc-DTPA cores. The results of the study showed that DTPA is a suitable tagging agent for 99mTc in the evaluation of colonic drug delivery systems containing water-soluble drugs by gamma scintigraphy.
authors.affiliation: Department of Pharmaceutical Sciences, College of Engineering, Andhra University, Visakhapatnam, A.P., India. krishnaysr112@rediffmail.com
authors.forename: Y S R
authors.initials: YS
authors.lastname: Krishnaiah
authors.forename: S
authors.initials: S
authors.lastname: Satyanarayana
authors.forename: Y V Rama
authors.initials: YV
authors.lastname: Prasad
authors.forename: S Narasimha
authors.initials: SN
authors.lastname: Rao
mesh_terms: D000328:Adult; D003106:Colon / Q000000981:diagnostic imaging*; D016503:Drug Delivery Systems / Q000379:methods*; D004341:Drug Evaluation / Q000379:methods; D005720:Gamma Rays; D006801:Humans; D008297:Male; D011849:Radioactive Tracers; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics*; D016284:Technetium Tc 99m Pentetate / Q000493:pharmacokinetics*; D013671:Technetium Tc 99m Sulfur Colloid / Q000493:pharmacokinetics*
chemical_list: D011849:Radioactive Tracers; D019275:Radiopharmaceuticals; D013671:Technetium Tc 99m Sulfur Colloid; D016284:Technetium Tc 99m Pentetate