Molecular-size fractionation of pentastarch, radiolabelling with 99mTc, and evaluation of biological behaviour in mice.
BACKGROUND
Pentastarch is used clinically as a plasma volume expander for the management of substantial blood loss. 99mTc labelled pentastarch may be useful as a diagnostic agent in place of 99mTc labelled red blood cells.


METHODS
Commercial pentastarch (PS; molecular weight (MW) 240 kDa) was separated according to molecular size by using chromatography, and the fractions were pooled as small (MW 128 kDa), medium (MW 277 kDa) and large (MW 510 kDa) pentastarch. We studied the effect of various physicochemical parameters on the efficiency of radiolabelling with 99mTc and on the stability of the products, and evaluated the biological properties of the 99mTc labelled preparations.


RESULTS
We developed an optimised kit formulation containing 3.25 mg pentastarch and 0.13 mg gentisic acid that can be reliably labelled with 99mTc at pH 6.6-8.2 with good stability. In mice, the 99mTc labelled medium pentastarch showed the more favourable blood retention properties (56% of initial blood activity is retained after 3 h) with lower liver levels.
Mang'era
Kennedy
K
Department of Radiopharmacy, Health Sciences Centre, Winnipeg, Manitoba, Canada. Kmangera@hsc.mb.ca
Krzyzelewski
Margaret
M
Greaves
Shelley
S
Greenberg
David
D
Billinghurst
Mervyn
M
D000818:Animals; D005591:Chemical Fractionation; D006863:Hydrogen-Ion Concentration; D006895:Hydroxyethyl Starch Derivatives / Q000097:blood / Q000737:chemistry* / Q000493:pharmacokinetics*; D007553:Isotope Labeling / Q000379:methods*; D008297:Male; D008657:Metabolic Clearance Rate; D051379:Mice; D008970:Molecular Weight; D009928:Organ Specificity; D010316:Particle Size; D019275:Radiopharmaceuticals / Q000097:blood / Q000737:chemistry / Q000493:pharmacokinetics; D013667:Technetium / Q000097:blood / Q000737:chemistry* / Q000493:pharmacokinetics*; D014018:Tissue Distribution
D006895:Hydroxyethyl Starch Derivatives; D019275:Radiopharmaceuticals; D013667:Technetium