Migraine Drug Ups Kidney Stone Risk
Study Provides New Details About the Effects of Topamax
"We can't say directly, given the size of the study, what the yearly risk for patients on topiramate for migraine is for getting kidney stones," Graybeal says.
In previous research on the drug when used by seizure patients, the kidney stone incidence was estimated at 1.5%, Graybeal notes in the paper.
In the general population, the incidence is about 0.2%, he says.
Put another way, in the general population, "one of 8 men and one in 15 women in the U.S. will develop a kidney stone in their lifetime," says Leslie Spry, MD, a nephrologist in Lincoln, Neb., and a spokesman for the National Kidney Foundation.
"It seems to confirm some of the things we already knew," says Joseph Hulihan MD, vice-president of medical affairs for Ortho-McNeil Neurologics, of the new study.
Topiramate provides effective relief for many headache sufferers, Graybeal notes. Unlike some other migraine medications, it isn't associated with weight gain. In fact, it's often associated with weight lossweight loss. In the three-month study, those on topiramate lost an average of 8.8 pounds, they found.
Those who stay on the medication can take dietary measures to reduce kidney stone risk, Graybeal says. Drink 32 to 64 ounces of water a day, he advises. Increasing your vitamin C, which lowers the urine pH, can help, he says. Ask your doctor for dose advice.
"We would advise increasing fluid intake when you are taking Topamax," agrees Spry. He tells patients to drink enough water that they need to get up at night to urinate -- and while they are up, to drink another glass.
Curb the salt, too, Spry says. "That means no added salt, not in cooking or at the table."
"There is also some evidence that if you change your diet a bit, adding more vegetable protein, like tofu, soy, eggs, dairy protein, that will help," Spry says.