Absorption, distribution, metabolism, and excretion of linear alkylbenzene sulfonate in rats

Absorption, distribution, metabolism, and excretion of calcium (straight-chain) alkylbenzenesulfonate (LAS-Ca) were compared with those of the corresponding sodium salt (LAS-Na) in rats by using labeled compounds. For both LAS-Ca and LAS-Na, the blood level of radioactivity atained maximum 2 hr after oral administration, decreased gradually with time, and reached a negligible level at 48 hr. The excretion rate of both compounds was rapid; in the case of LAS-Ca, 89.0% of the administered radioactivity and in LAS-Na, 91.5% of that were excreted after 24 hr. Further, after 48 hr, in the case of LAS-Ca, 95.6% of the administered radioactivity and in LAS-Na, 99.4% of that were excreted. The proportion of excreted radioactivity in urine and feces of rats administered LAS-Ca or LAS-Na was almost the same, and about 50% of the administered radioactivity was excreted during 7 days. The distributed concentration of radioactivity in the corresponding tissues of LAS-Ca and LAS-Na indicated almost the same values at 4, 48, and 168 hr after oral administration. The radioactive substances in urine and feces of rats administered LAS-Ca or LAS-Na were separated by thin-layer chromatography (TLC), and the Rf values of metabolites in urine and feces of rats administered LAS-Ca were similar to those of LAS-Na. Both compounds were metabolized and original LAS-Ca or LAS-Na was not detected on the TLC plate. These results indicated that the behavior of LAS-Ca was similar to that of LAS-Na in vivo. (author)