Comparison of pharmacodynamic effects and plasma levels of oral and rectal ergotamine

Plasma levels and the vasoconstrictive effect of 1 mg ergotamine tartrate given as tablets or suppositories were compared. In a crossover study, eight male volunteers received tablets or suppositories containing ergotamine in a drug combination (Anervan) and, as a control, suppositories without ergotamine. Blood sampling and measurement of toe-arm systolic gradients with a strain-gauge technique were done for up to 6 h and again after 24 h and 48 h. Only 29 of 160 blood samples contained detectable (greater than 0.1 ng/ml) amounts of ergotamine, and kinetic comparison could not be performed. Only ergotamine-containing suppositories caused a significant (p less than 0.008) decrease in toe-arm systolic gradient which was significantly different (p less than 0.003) from the effects of ergotamine tablets and control suppositories. Rectal ergotamine is thus more biologically active, for the factor used, than oral ergotamine. We suggest that a rectal dose of 1 mg ergotamine tartrate should be tried as the initial dose in the treatment of migraine attacks.