Dear Dr. Roach: I鈥檝e suffered from essential tremor for 16 years. I take 500 mg of primidone and 40 mg of propranolol twice daily. I鈥檝e gradually increased the dose over the years, and the combination works quite well. What is the highest dose of these medications that I can take? Also, are there any new drugs on the market that have been proven to help? S.S.
Primidone, a medication indicated for seizures, often is used off-label for essential tremor. The normal dose for essential tremor is 250-500 mg at night, but doses up to 750 mg sometimes are used. For seizures, the highest recommended dose is 2,000 mg, so although yours is at the high end of normal for essential tremor (鈥渆ssential,鈥� by the way, simply means we don鈥檛 know what is causing it; it isn鈥檛 essential for anything), you still are at a dose that鈥檚 well below the safe limit. I suspect that because you have been on it for so long, your body is used to this dose. The usual starting dose is 25 mg.
Propranolol is used for many conditions, including high blood pressure and preventing migraines, but its use in essential tremor also is off-label, meaning that the Food and Drug Administration has not approved the drug for use for this condition. 鈥淥ff-label鈥� also can mean that the FDA has approved the drug only for a particular age group, route of administration or dosage range; this doesn鈥檛 necessarily mean your prescription is wrong or dangerous, only that it hasn鈥檛 been approved by the FDA. In your case, the combination of primidone and propranolol frequently is used and recommended in the medical literature. For essential tremor, experts have recommended doses up to 320 mg per day, but the dose can be limited by slow heart rate or low blood pressure.
Other medications frequently used for essential tremor include gabapentin and topiramate. There also are surgical treatments, deep brain stimulation, gamma knife radiation and ultrasound for resistant cases.
