Almotriptan × Dihydroergotamine

Both drugs constrict blood vessels. Almotriptan stimulates serotonin receptors in artery walls, including the coronary arteries, and dihydroergotamine acts on the same receptors and also on adrenergic receptors. Triptans can cause coronary artery spasm and ergot drugs cause prolonged vasospasm, so their vasoconstrictor effects may add up. In a study of 12 healthy volunteers, oral almotriptan with ergotamine (the closest relative of dihydroergotamine) caused no extra vasospasm, but an additive effect is theoretically possible.

Coronary spasm shows as pressure, pain or heaviness in the chest, throat, neck or jaw, and can progress to myocardial infarction or dangerous arrhythmias. Spasm of other arteries can cause cold, pale or numb fingers, abdominal pain with bloody diarrhoea from bowel ischaemia, sudden loss of vision or signs of stroke. Dihydroergotamine can also raise blood pressure sharply.

The combination is contraindicated (almotriptan ficha técnica, Spanish Agency of Medicines, AEMPS: ergotamine and its derivatives; almotriptan and dihydroergotamine labels, US Food and Drug Administration, FDA). Keep at least 24 hours between the two drugs, in either order (almotriptan and dihydroergotamine labels, FDA). The shorter 6-hour interval after almotriptan in the Spanish ficha técnica refers to ergotamine. For dihydroergotamine, keep 24 hours both ways (FDA labels). If chest, throat, neck or jaw pain or tightness appears after a dose, withhold further doses and assess the patient for cardiac ischaemia (almotriptan ficha técnica, AEMPS). If cold, pale fingers, abdominal pain with blood in the stool or vision loss appear after a dose, assess arterial blood flow (almotriptan label, FDA). Taking triptans and ergot drugs, alone or together, on 10 or more days a month can lead to medication overuse headache (dihydroergotamine label, FDA).