Absorption and excretion of the hydrophobic surfactant, 14C-poloxalene 2930, in the rat.

Absorption and excretion of 14C-Poloxalene 2930 (PX), a nonionic hydrophobic surfactant of large molecular weight, were studied using bile fistula rats. Approximately half of the dose infused intraduodenally was absorbed and some of the absorbed surfactant was excreted in bile. The remainder was excreted in urine. Only trace quantities of the 14C-PX were recovered in liver and carcass at termination of the study. Two studies were also performed with 14C-PX incorporated into the diet. In the first feeding study of 7 days duration, most of the agent was excreted via the gastrointestinal tract within 72 hr of discontinuing treatment. In the second study, rats were fed dietary 14C-PX for 7, 14, or 23 days to determine whether the surfactant continued to accumulate in the body as the test period was extended. Further accumulation did occur between the 7th and 14th days but not when feeding was continued for a total of 23 days. Of the amount of 14C-PX ingested after 23 days of feeding, essentially all was excreted by the end of 7 days after discontinuing treatment. These studies indicate that despite its large molecular weight of about 3,000 some 14C-PX is absorbed. Furthermore, absorbed material is promptly excreted in bile and urine with little retained in body tissues.