Objective      To investigate the pharmacokinetics of

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I- tick anticoagulant peptide (TAP)-staphylococcal superantigen like protein-5 (SSL5) in normal rabbits.       Methods       TAP-SSL5 was labeled directly with Na

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I using the idogen method. The best compartment model and its pharmacokinetic parameters were determined in rabbits （n=6） by

measuring the blood radioactive concentrations at 1.5

3

5

10

30

60

120

240 and 480 min after bolus injection of 18.5 MBq

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I-TAP-SSL5.       Results      The labeling rate and radiochemical purity of

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I-TAP-SSL5 was (67.32±9.91)% and (91.62±3.22)% respectively. The specific activity was (30.2±4.4) TBq/μmol. TAP-SSL5 showed two compartment model in rabbit

the main parameters of pharmacokinetics were as follows: t

1/2α

=（0.08±0.04） h

t

1/2β

=（4.97±0.75） h

clearance （CL）=0.015±0.011 ml/h

K

12

=(6.651±3.642)/h

and K

21

=(4.072±1.737)/h.       Conclusion        The pharmacokinetic of

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I-TAP-SSL5 fits the two compartment model (weight coefficient =1) in normal rabbits. Its clearance is low

which ensures more chance to combine with tissues．