Linear pharmacokinetics of intravenous ergotamine tartrate

Ergotamine tartrate 0.5, 0.25 and 0.125 mg was administered i.v. to 6 volunteers in a cross-over study. Its pharmacokinetic characteristics were evaluated from plasma concentration-time data determined by HPLC. The clearance and volume of distribution were independent of the dose. The ratio between blood and plasma ergotamine concentrations in 4 subjects ranged from 0.41-0.67, indicating the lack of binding to blood cells. Ergotamine was found to be a high clearance drug, average 2.21/min/70 kg body wt. suggesting extrahepatic clearance. A possible transient decrease in liver blood flow caused by ergotamine did not seem to affect the linearity of its kinetics.