Abstract
The absorption, distribution, excretion and metabolism of recombinant human interleukin-2 (S-6820) were studied following intravenous or subcutaneous injection at a dose of 5×105U/kg to rats. Concentrations of S-6820 in serum, tissues and other body fluids were measured by a bioassay and an enzyme immunoassay.
1. After intravenous injection of S-6820 to rats, serum levels of S-6820 decreased biphasically and the half-lives of the α phase and β phase were 2. 4 min and 16min, respectively.
2. Absorption ratio after subcutaneous injection of S-6820 was about 37%.
3. After repeated intravenous injection of S-6820 once a day for 5 days, the levels of S-6820 in serum and tissues reached the same levels as after single administration. No accumulation was observed.
4. After intravenous injection of S-6820, especially high level was observed in the kidney, however, it decreased rapidly (t1/2=11min). The levels of S-6820 in the other organs (spleen, lung, heart and liver) were lower than the serum level.
5. After intravenous injection of S-6820 to 20-th day pregnant rat, S-6820 in the amniotic fluid and fetus was not detected.
6. After intravenous injection to lactating rats, the transfer of S-6820 from blood to milk was minimal.
7. A little of S-6820 was found in the bile by EIA. S-6820 was not detected in the urine by EIA method.
8. The disappearance rates of S-6820 in rats changed from t1/2(β)=0.41hr in sham operated rats to t1/2(β)=1.57hr in rats with renal excision. The kidney appeared to be the main metabolic site.
