Topiramate (Topamax) is one of the most popular preventive drugs for migraine. This is not because it is more effective than other approved drugs. It is because it can cause weight loss. The drug manufacturer tried to get it approved for weight loss. The FDA, however, felt that while the side effects may be acceptable when treating epilepsy or migraines, they are not acceptable when treating obesity. You can argue that obesity is as serious a disorder but the FDA decision underscores the fact that the drug can have serious side effects.
Cognitive side effects can be obvious to most patients but for some, they are not. People begin to attribute their memory and word-finding difficulties to stress, lack of sleep, early-onset dementia, and other reasons. They have told me that they feel stupid on this drug, hence the moniker, Dopamax. Topiramate can also cause irritability, depression, fatigue, osteoporosis, glaucoma, and in 20%, kidney stones (10% with symptoms and 10% without). Like the other FDA-approved epilepsy drug, valproate, it is contraindicated in pregnancy because it can cause birth defects. I urge patients who are taking these drugs to be very vigilant about contraception.
In large clinical trials, 55% of patients had relief and were able to tolerate the drug. Postmarketing studies show that 40% of epilepsy patients stop the drug. Of these, one-fifth stop it because of lack of efficacy, almost half due to side effects, 12% due to both, and the rest for other reasons. It is likely that even a higher percentage of migraine patients stop the drug. Having an epileptic seizure is much more dangerous than having an attack of migraine.
The starting dose of topiramate is 25 mg nightly with a weekly increase of 25 mg up to 100 mg. Occasionally, patients benefit from a higher dose, up to 200 mg. If cognitive side effects are mild but bothersome, it may be worth trying a long-acting form of topiramate which can have fewer side effects. There are two such products on the market in the US – Qudexy and Trokendi. They are much more expensive than generic topiramate.
Topiramate is also approved for migraines in adolescents, ages 12 to 17. In this age group, it can cause or worsen an eating disorder.
Because of its side effects, topiramate is not one of the top choices of preventive drugs. The only time I move it up my list is when a patient is obese and is struggling to lose weight.
