Ergotamine, Dihydroergotamine: Current Uses and Problems

P. Tfelt-Hansen

Disclosures

Curr Med Res Opin. 2001;17(1s) 

In This Article

Pharmacological Background†‡

The ergot alkaloids have a complex mode of action that involves interaction with a variety of receptors. In therapeutically-relevant concentrations, ergotamine and dihydroergotamine act as agonists at Éø-adrenoceptors, 5-HT (particularly 5-HT1B/1D and 5-HT2 ) and dopamine D2 receptors.

The most important and conspicuous pharmacological effect of ergot alkaloids is undeniably the vasoconstrictor action. Extensive studies in animals show that this vasoconstrictor effect is particularly marked within the carotid vascular bed. Ergotamine causes a long-lasting (at least 24 h) vasoconstriction of leg arteries in man. A similar long lasting venoconstrictor effect (at least 8 h) has been observed after a single dose of dihydroergotamine. The oral and sublingual bioavailability of ergotamine is estimated to be <1%, whereas the rectal bioavailability is estimated to be 1-3%. The elimination half-life of ergotamine is 2 h.

After i.v. injection, dihydroergotamine is quickly distributed and eliminated with a mean terminal half-life of 13-15 h. Nasally-administered dihydroergotamine becomes rapidly available to the systemic circulation, with peak plasma levels achieved in approximately 0.8 h. The bioavailability of intranasal dihydroergotamine is approximately 40%.

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