Ergotamine preparations
Ergotamine and its derivatives may be used as
abortive or sympto-matic therapy for migraine.
Some common preparations used for migraine include:
·
ergotamine, available in sublingual and oral tablets and supposi-tories
(combined with caffeine)
·
dihydroergotamine, available in injectable and intranasal forms.
Ergotamine is incompletely absorbed from the GI
tract. The in-tranasal form of dihydroergotamine is rapidly absorbed. Peak
plasma concentration, following subcutaneous injection, is within 45 minutes,
and 90% of the dose is plasma protein-bound. Ergota-mine is metabolized in the
liver, and 90% of the metabolites are ex-creted in bile; traces of unchanged
drug are excreted in urine.
Ergotamine-derivative antimigraine effects are
believed to be due to blockade of neurogenic inflammation. They also act as
partial agonists or antagonists at serotonin, dopaminergic, and
alpha-adrenergic receptors depending on their site. Ergotamine prepara-tions
often need to be prescribed with antiemetic preparations when used for
migraine.
Dihydroergotamine, a hydrogenated form of
ergotamine, dif-fers mainly in degree of activity. It has less vasoconstrictive
action than ergotamine and much less emetic potential.
Ergotamine preparations are used to prevent or
treat vascular headaches, such as migraine, migraine variant, and cluster
headaches. Dihydroergotamine is used when rapid control of mi-graine is desired
or when other routes are undesirable.
Propranolol and other beta-adrenergic blocking
drugs block the natural pathway for vasodilation in patients receiving
ergotamine preparations, resulting in excessive vasoconstriction and cold
ex-tremities.
·
There may be an increased risk of weakness, hyperflexion, and
incoordination when using ergotamine preparations with SSRIs.
·
Sumatriptan may cause an additive effect, increasing the risk of
coronary vasospasm. Don’t give any ergotamine prepa-rations and triptans within
24 hours of each other.
·
Drugs that inhibit the
CYP3A4 enzyme (such as ery-thromycin, clarithromycin, ritonavir, nelfinavir,
indinavir, and azole-derivative antifungal agents) may alter the metabolism of
ergotamine, resulting in increased serum concentrations of er-gotamine. This
increases the risk of vasospasm and cerebral or peripheral ischemia. These
drugs shouldn’t be used together.
·
Vasoconstrictors may
cause an additive effect when given with ergotamine preparations, increasing
the risk of high blood pres-sure. (See Adverse
reactions to ergotamine derivatives.)
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