Pharmacokinetics of Ethanol in Arterial and Venous Blood and in End-Expired Breath during Vasoconstriction and Vasodilation.

We studied the influence of vasoconstriction and vasodilation on the concentrations and the pharmacokinetics of ethanol in arterial blood (a), venous blood (v), and end-expired breath (b). Ethanol 0.4 g kg(minus sign1) was given by intravenous infusion over 30 min to 12 healthy male volunteers, once in the morning and again in the afternoon the same day. During one infusion, the hand used to obtain venous blood was either cooled in water to 13--15 degreeC (N = 6 subjects) or warmed in a heating box at 60 degreeC (N = 6 subjects). Our results show that a--v differences and the pharmacokinetics of ethanol are sensitive to the constriction or dilation of blood vessels caused by local cooling or heating. Cooling of the hand doubled the a--v and b--v differences during infusion of ethanol, whereas warming reduced these differences by 10--80%. The a--b difference was positive during infusion but always became negative within 5 min after the infusion ended. However, cooling maintained the increased a--v difference for another 45 min after the infusion. Fitting of the data into a pharmacokinetic model consisting of a first-order distribution function and a zero-order (saturated Michaelis--Menten) elimination function showed that cooling altered the pharmacokinetic parameters describing the elimination of ethanol, whereas warming altered the parameters describing the distribution phase.