This blog has many posts about the role of magnesium in the prevention of migraines and clinical trials of magnesium. Another study was just published by Iranian doctors in The Journal of Headache and Pain.

Unfortunately, like other studies, this one has a major flaw. Magnesium was given to all migraine sufferers, whether they were deficient in magnesium or not. If you are not deficient, taking extra magnesium will not help. For those who are deficient, however, the effect can be dramatic.

Another problem with this and several previous studies is the use of poorly absorbed salts of magnesium. In this case, magnesium oxide.

Patients in this study were divided into three groups. One group was given valproate (200 mg twice a day), the second group, valproate with magnesium oxide (250 mg twice a day), and the third group, magnesium oxide alone (also 250 mg twice a day). There were 82, 70, and 70 patients in each group, respectively.

Patients in the two groups that included valproate did better than those in the group taking magnesium alone. The combination of valproate with magnesium was more effective than valproate alone.

Surprisingly, the authors mention nothing about side effects. Valproate is one of the last drugs I use in migraine patients. It has many potential side effects, including weight gain, hair loss, tremor, nausea, and others. The majority of migraine sufferers are women of childbearing age and up to half of the pregnancies in the US are unplanned. So, another major reason I rarely prescribe this drug is that valproate is contraindicated in pregnancy. It can cause congenital malformations and developmental problems.

Zonisamide (Zonegran) is an epilepsy drug similar to topiramate in its mechanism of action. Unfortunately, it shares its side effects as well. These include fatigue, difficulty with concentration and memory, nausea, and other. However, because they are not identical drugs, some patients tolerate zonisamide better than topiramate.

One study showed that 44% of 172 patients who did not respond to topiramate did respond to zonisamide with 13% having an excellent response. A similar study in 63 patients who did not respond to topiramate also showed benefit from zonisamide as did 34 patients in another study. Zonisamide also helped 8 out of 12 children who did not respond to other medications.

The dose of zonisamide ranges from 50 to 400 mg a day, but most patients need 100-200 mg.

Zolmitriptan (Zomig, Zomig ZMT, Zomig NS) is one of seven triptans sold in the US. It is available in tablets, orally disintegrating tablets, and nasal spray. The nasal spray is approved for children 12 and older. Both tablets and the spray are available in 2.5 mg and 5 mg strength. The maximum daily dose is 10 mg.

However, it is washed out of the body within a few hours. This means that taking three 5 mg tablets spread out over 24 hours poses no danger. Three doses a day is the approved limit for rizatriptan (Maxalt). There is no reason why this should not apply to zolmitriptan and other triptans except for the long-lasting frovatriptan. Fortunately, it is uncommon that a patient requires three doses in one day. And if a patient does need to take a triptan more than twice a day, we usually try a different drug that may work with a single dose.

One advantage of the nasal spray is that it tends to have a faster onset of action. Another advantage is that can be taken when severe nausea or vomiting precludes the use of oral medications. My impression is that zolmitriptan spray is more effective than the original sumatriptan spray. The amount of fluid in a single dose of Zomig is less than that in sumatriptan and the spray droplets are of smaller size. This leads to better retention of fluid in the nasal passages and better absorption.

The new version of sumatriptan spray, Tosymra contains 10 mg of sumatriptan while the original spray contains 20 mg. However, it comes out in smaller droplets and contains an ingredient that allows for better absorption. This formulation of sumatriptan spray appears to be as effective as Zomig NS.

Zolmitriptan nasal spray is expensive (as is Tosymra) because it is available only as a branded product. It will lose its patent protection in 2021.

Verapamil (Calan, Isoptin) is an effective drug for the prevention of cluster headaches. It is sometimes used for migraines as well. However, the evidence for its efficacy is weak. A double-blind crossover trial by Dr. Glen Solomon and his colleagues in Ohio examined the effect of 320 mg of verapamil on 12 migraine patients. The drug was more effective than the placebo. Other small studies also suggested that it might help some patients.

Verapamil has a reputation among headache specialists as being effective for the prevention of frequent migraine auras and other neurological symptoms that occur with migraines. Unfortunately, there are no controlled trials to support this impression.

The starting dose of verapamil is 120 mg a day with a possible escalation up to 480 mg. For cluster headaches, the starting dose is 240 mg and the maximum dose is as high as 960 mg. Verapamil can cause arrhythmia (irregular heartbeat), especially at higher doses. I recommend an electrocardiogram before every increase of the dose above 240 mg.

The two most common side effects of verapamil are constipation and swelling of the feet. In some of my patients, constipation was severe and resistant to treatment. They had to stop taking the drug.

Venlafaxine (Effexor) is the first drug in the serotonin-norepinephrine reuptake inhibitors (SNRI) class. It was approved by the FDA for the treatment of depression in 1993.

At low doses, venlafaxine works as a selective serotonin reuptake inhibitor (SSRI) such as fluoxetine (Prozac). SNRIs are considered to be effective for the treatment of pain and migraine headaches. SSRIs are not. A review of studies that involved a total of 418 patients showed that SNRIs are effective for the prevention of migraines. The class of SNRIs includes duloxetine (Cymbalta), desvenlafaxine (Pristiq), milnacipran (Savella), and levomilnacipran (Fetzima). Milnacipran is the only SNRI that is approved by the FDA for the treatment of fibromyalgia rather than depression.

In treating migraines, a 60-patient trial showed that the 150 mg dose is more effective than 75 mg.

Another double-blind crossover study comparing venlafaxine with amitriptyline showed them to be equally effective. Venlafaxine had fewer side effects than amitriptyline.

Venlafaxine is started at 37.5 or 75 mg dose. After a week or two, the dose is increased to 150 mg. The maximum daily dose of venlafaxine is 450 mg.

Potential side effects include insomnia, drowsiness, fatigue, nausea, dizziness, suicidal thoughts in depressed children and young adults, and others.

Just like with other SNRIs, sudden discontinuation of venlafaxine can cause withdrawal symptoms. These may include one or more of the following: dizziness, headache, nausea, diarrhea, paresthesia (pins-and-needles), irritability, vomiting, insomnia, anxiety, sweating, and fatigue. SNRIs are stopped after a slow and gradual reduction of the dose.