Effect of Aspirin on Urinary Excretion of 6-Ketoprostaglandin F1α

Abstract

The effect of oral administration of acetylsalicyclic acid (1200 mg/day for 3 days) on the urinary excretion of 6-ketoprostaglandin F1.alpha. [6-ketoPGF1.alpha.] was studied in normal human subjects as an index of prostacyclin [PGI2] production in vivo. [PGI2 production may be an important mechanism by which vascular endothelium maintains a non-thrombogenic surface.] The concentrations and excretion rate in urine fell to 45% of pretreatment levels in 3 days, but returned to pretreatment values after 7 days. Apparently, PGI2 production in vivo is only partially inhibited by high doses of aspirin and there are sites of production of PGI2 which are protected from inhibition by aspirin and which contribute to urinary 6-ketoPGF1.alpha.. The measurement of 6-ketoPGF1.alpha. in urine may be of only limited value as an index of the metabolism of vascular tissue in vivo.