[Effects of 7 d head-down tilt (-20 degrees) immobilization on pharmacokinetics of gentamicin in rabbits].

Objective: To observe pharmacokinetic changes under simulated weightlessness in relevant to body flood flow changes.
Method: Gentamicin was selected as probe drug in the present study, and rabbits exposed to Head-Down Tilt (HDT, -20 degrees) immobilization were selected as simulated weightlessness animal model. Seven rabbits were treated inf. with 3 mg/kg of gentamicin sulfate pre-HDT and 7 d after HDT. Gentamicin blood samples within 4 h after administration were analyzed by TDxFLx.
Result: The distribution of gentamicin postponed significantly: a significant decrease in alpha from (0.1838 +/- 0.1076) min-1 before HDT to (0.0591 +/- 0.0334) min-1 after HDT; a significant increase in t1/2 alpha from (5.30 +/- 3.55) min to (15.04 +/- 7.49) min; a significant decrease in k12 from (0.1025 +/- 0.0721) min-1 to (0.0181 +/- 0.0161) min-1, a increase trend in V(C) and V(D). After HDT, CL(S) of gentamicin increased from (2.2 +/- 0.5) ml min-1 kg-1 to (2.7 +/- 0.3) ml min-1 kg-1.
Conclusion: Simulated weightlessness might induce pharmacokinetic changes.