The effect of dihydroergotamine on platelets, coagulation and fibrinolysis, studied in healthy humans and in dogs.

The effect of dihydroergotamine (DHE) on platelets, coagulation and fibrinolysis was studied in healthy volunteers ex vivo before and after intravenous administration (0.5 mg). In addition, the effect of DHE in different concentrations on platelet aggregation was evaluated in vitro. Haematocrit was found to increase, as did factor VIII:C and antithrombin III - though the latter increases were not significant when correction was made for the altered haematocrit. Though platelet function ex vivo was unchanged, inhibition of adrenaline induced platelet aggregation was noted in vitro when the plasma concentrations of added DHE were higher than those obtained with clinically relevant doses. No effect on fibrinolysis was noted.