The effect of ergotamine and dihydroergotamine on cerebral blood flow in man.

The effects of ergotamine and dihydroergotamine on cerebral blood flow was investigated 4 hours after i.v. injection as these drugs might be of importance for migraine treatment. Eight normal male volunteers (not suffering from migraine) received 0.5 mg ergotamine and 1 mg dihydroergotamine i.v. Cerebral blood flow was measured by the xenon-133 inhalation method and single-photon-emission computerized tomography before and after intravenous acetazolamide administration (1 g). Cerebral blood flow was measured before and 4 hours after ergotamine and dihydroergotamine administration. Strain-gauge measurements of toe-arm systolic gradients were used to monitor the effect of the drug on leg arteries. Mean hemispheric and regional cerebral blood flow was unchanged after either drug (mean +/- SEM, ml/100 g/min): for ergotamine, 57 +/- 3 before and 57 +/- 3 at 4 hours; for dihydroergotamine, 54 +/- 2 before and 55 +/- 2 at 4 hours. The acetazolamide response was unchanged as well. Only ergotamine decreased the toe-arm systolic gradient significantly (22 mm Hg at maximum after 240 minutes; p less than 0.02). Thus, our study did not support the belief that ergot alkaloids should be withheld from patients during attacks of classic migraine, but this has to be investigated further. The discrepancy in the peripheral effects of ergotamine and dihydroergotamine might also be of clinical importance.