100 Migraine drugs, A to Z: amiloride

Only about 20% of migraine sufferers experience an aura. The most common type of aura is visual and it typically consists of partial obscuration of vision with colorful zigzags and blind spots spreading over half of the visual field of both eyes. Sometimes, the aura consists of gradual narrowing of the visual fields which ends in tunnel vision or complete loss of vision. The typical duration is 20 to 60 minutes and usually the aura itself is not disabling, but the headache that follows can be more severe than during attacks without aura. Migraine aura can occur without a subsequent headache. In some people aura does interfere with normal functioning and can be more disabling than the headache. In rare instances, the visual disturbance persists for days, weeks, and months.

In such cases I do a battery of blood tests, including for RBC magnesium, vitamin B12, homocysteine, CoQ10 levels, and other. If RBC magnesium level is low or at the bottom of normal range, a gram of magnesium sulfate given intravenously can abort the aura. We sometimes give an infusion of magnesium without first doing a blood test.

Amiloride (Midamore) is a potassium-sparing diuretic (water pill), which means that unlike most diuretics, it does not deplete potassium. It is used to treat high blood pressure, heart failure and to remove excess fluid in the body. It has been reported to reduce aura and headache symptoms in 4 of 7 patients with otherwise intractable aura. Potential side effects of amiloride include dizziness, nausea, stomach pain, and diarrhea.

Other diuretics, such as acetazolamide, which is also used for barometric pressure-induced migraines and furosemide have also been reported to stop a prolonged visual aura. Other approaches to treat a persistent aura include the use of preventive migraine medications, such as a blood pressure medication, verapamil (Calan) or one of the epilepsy drugs, such as topiramate (Topamax), divalproex sodium (Depakote), or lamotrigine (Lamictal). An infusion of divalproex sodium derivative, valproic acid (Depakene) can be also tried.