Pharmacokinetics of etomidate in surgical patients

Eight adult surgical patients received a single i.v. injection of etomidate-base (mean 0.22 mg.kg(-1)). Venous blood samples were drawn at frequent intervals for up to 10 hr following drug administration. Plasma concentrations of etomidate were measured with a newly developed capillary gas chromatographic method. Plasma concentrations fitted best to an open three compartment pharmacokinetic model by a non-linear regression computer programme. The following mean parameters were computed: distribution half-life 2.8 + or - 2.3 min, half-life of the alpha-phase: 22.3 +or - 10.4 min and half-life of the beta-phase 208.8 + or - 64.9 min, distribution volume 3.68 + or - 0.66 l.kg(-1) (Vd area) and 2.16 l.kg(-1) (Vdss) and plasma clearance 879 + or - 135 ml.min(-1). High tissue uptake is indicated by the rapidity and the large volume of distribution. Etomidate is rapidly redistributed from the central to peripheral compartments and rapidly eliminated by metabolism.