chapter
Antimigraine drugs
Pages 8

Avoid co-administration. If absolutely necessary, advise patients to discontinue treatment immediately if numbness and tingling of the extremities are felt

ERGOT DERIVATIVES ANTIVIRALS – PROTEASE INHIBITORS, EFAVIRENZ

≠ ergotamine/methysergide levels with risk of toxicity

↓ CYP3A4-mediated metabolism of ergot derivatives

Avoid co-administration

ERGOT DERIVATIVES BETA-BLOCKERS Three cases of arterial vasoconstriction and one of ≠ BP occurred when ergotamine or methysergide was added to propanolol or oxprenolol

Ergotamine can cause peripheral vasospasm, and absence of betaadrenergic activity can ≠ risk of vasoconstriction

Ergot derivatives and beta-blockers are often co-administered without trouble; however, monitor BP at least weekly until stable (watch for ≠ BP) and warn patients to stop the ergot derivative and seek medical attention if they develop cold, painful feet

N ER

V O

U SSY

STEM D

R U

G S

A N

TIM IG

R A

IN ED

R U

G S229

NERVOUS SYSTEM DRUGS ANTIMIGRAINE DRUGS Ergot derivatives

gangrene

Possibly ≠ bioavailability by ↓ presystemic metabolism. Constituents of grapefruit juice irreversibly inhibit intestinal cytochrome CYP3A4

Monitor for ≠ side-effects and stop intake of grapefruit preparations if side-effects occur

ERGOT DERIVATIVES H2 RECEPTOR BLOCKERS – CIMETIDINE

≠ ergotamine/methysergide levels with risk of toxicity

Inhibition of metabolism via CYP3A4

Avoid co-administration

ERGOTAMINE, METHYSERGIDE

5-HT1 AGONISTS – TRIPTANS

≠ risk of vasospasm Additive effect 1. Do not administer ergotamine and almotriptan, rizatriptan, sumatriptan or zolmitriptan within 6 hours of each other 2. Do not administer methysergide and almotriptan, rizatriptan, sumatriptan or zolmitriptan within 24 hours of each other 3. Do not administer an ergot derivative and eletriptan or frovatriptan within 24 hours of each other

ERGOT DERIVATIVES SYMPATHOMIMETICS

ERGOT DERIVATIVES SYMPATHOMIMETICS Risk of ergot toxicity when ergotamine is co-administered with sympathomimetics

Uncertain Watch for early features of ergotamine toxicity (vertigo and gastrointestinal disturbance)

ERGOT DERIVATIVES DIRECT Case report of gangrene when dopamine was given to a patient on ergotamine

Thought to be due to additive vasoconstriction

Titrate dopamine carefully

N ER

V O

U SSY

STEM D

R U

G S

A N

TIM IG

R A

IN ED

R U

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Mechanism Precautions

ALMOTRIPTAN, ELETRIPTAN

MACROLIDES – CLARITHROMYCIN, ERYTHROMYCIN, TELITHROMYCIN

≠ plasma concentrations of almotriptan and eletriptan, with risk of toxic effects, e.g. flushing, sensations of tingling, heat, heaviness, pressure or tightness of any part of body including the throat and chest, dizziness

Almotriptan is metabolized mainly by CYP3A4 isoenzymes. Most CYP isoenzymes are inhibited by clarithromycin to varying degrees, and since there is an alternative pathway of metabolism by MAOA, toxicity responses will vary between individuals

Avoid co-administration

ALMOTRIPTAN RIFAMPICIN Possible ↓ plasma concentrations of almotriptan, with risk of inadequate therapeutic efficacy

One of the major metabolizing enzymes of almotriptan – CYP3A4 isoenzymes – are induced by rifampicin. As there are alternative metabolic pathways, the effect may not be significant and can vary from individual to individual

Be aware of the possibility of ↓ response to triptan, and consider ≠ of dose if considered to be due to interaction

ZOLMITRIPTAN QUINOLONES Possible ↓ plasma concentrations of zolmitriptan, with risk of inadequate therapeutic efficacy

Possibly induced metabolism of zolmitriptan

Be aware of possibility of ↓ response to triptan, and consider ≠ of dose if considered to be due to interaction.