Pharmacokinetics of dihydroergosine in rats after intravenous and oral administration.

Wistar rats received an intravenous dose of 20 micrograms/kg and an oral does of 40 micrograms/kg 3H-Dihydroergosine. Concentrations of radioactivity were measured in plasma, bile, urine, and faeces, and pharmacokinetical parameters of an open two compartment model were calculated. After intravenous injection and oral administration 3H-Dihydroergosine is rapidly lost from the central compartment with distribution rate constants alpha = 0.889 h-1 and beta = 0.722 h-1, respectively. Biological half life in the elimination phase after both application is nearly the same t 1/2 = 13.6 h. The volume of central compartment is Vc = 3.075 l/kg and the volume of distribution Vd beta = 30.75 l/kg. The fraction of 3H-Dihydroergosine absorbed after oral administration, calculated from areas under the curves upon oral and intravenous administration, is 31%. The percentage of 3H-radioactivity eliminated with bile was 98.3% of the dose within 72 hours after intravenous and 29.3% after oral administration. The main portion of the administered 3H-radioactivity was recovered in faeces -66.1% after intravenous and 81.3% after oral administration, while only 17.4% and 4.9% of the administered dose was eliminated in the urine within 120 hours, respectively.