In vitro studies on the duration of action of dihydroergotamine.

Changes in tension were monitored isometrically on spiral strips from canine saphenous and femoral veins. Dihydroergotamine elicited an increase in tension at threshold concentrations (about 0.1 ng/ml) which are in accordance with mean plasma levels found in vivo after single oral doses in dog and man. In addition, it was demonstrated that the dihydroergotamine-induced venoconstriction persisted for several hours even when the drug was eliminated from the bathing solution.