The purpose of this study was to prospectively study the human pharmacokinetics of an ultrasound (US) contrast agent through its active ingredient, dodecafluoropentane (DDFP). Expired air and blood samples were collected from 24 volunteers after IV administration from 0.01 to 0.1 mL/kg. They were analyzed by a gas chromatographic method specially adapted to the study of DDFP. Blood data fitted to an open one-compartment model. Elimination half-life range was 1.8 to 2.5 min. The area under the curve was correlated to the dose (r(2) = 0.99). Mean blood clearance ranged from 30 to 49 mL/min kg. Blood apparent distribution volume ranged from 0.09 to 0.15 L/kg. In expired air, DDFP concentration exhibited a biexponential decay. The percentage of recovery was 98 +/- 19% at 2 h. No extraneous peaks were observed, indicating no detectable DDFP metabolites. It was concluded that DDFP pharmacokinetics in blood fitted to an open one-compartment model with a fast elimination half-life. Recovery in expired air was almost complete 2 h after administration.