The Pharmacokinetics of Dihydroergotamine in the Beagle Dog after a Single Intravenous Injection and after a Continuous Intravenous Infusion

Abstract The pharmacokinetics of dihydroergotamine (DHE) was studied in 6 beagles after a single 2.0 mg intravenous dose and after a continuous intravenous infusion (dose 2.0 mg, infusion time 51 min. = 2.8–3.5 μg/min./kg). The concentrations of DHE in the plasma during 6 hours were determined by a radioimmunoassay. The mean α-phase T1/2 was 0.92 min. and 5.93 min., the mean β-phase T1/2 was 104.42 min. and 115.79 min., and the mean plasma clearance value 202.88 ml/min. and 234.79 ml/min. after a single intravenous injection and a continuous infusion administration, respectively. Similarly, the V_dc — values were 0.12 l/kg and 0.38 l/kg and the V_dβ — values 3.41 l/kg and 4.31 l/kg. Only the α-phase T_1/2 and the V_dc-values differed significantly from each other. The simulated concentrations of DHE in the peripheral compartment increased rapidly explaining its fast effect on the vasculature in clinical use.