topiramate, Topamax (cont.)

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DOSING: Most commonly, topiramate is started in low doses, 25 or 50 mg per day, and then increased slowly by 25 to 50 mg per week until an effective daily dose is reached. For children 10 years or older and adults the dose may be increased by 100 mg in week 5 and 6 when topiramate is used alone. This slow approach to treatment reduces side effects. The recommended final adult dose is 200-400 mg administered as two divided doses daily.

In children, the starting dose is up to 25 mg (1 to 3 mg/kg/day), taken nightly for the first week. The dose is then increased at 1 or 2 week intervals by 1 to 3 mg/kg/day administered in two divided doses. The target dose is 5 to 9 mg/kg per day in two divided doses.

Migraine is treated 25 mg nightly for the first week then increased by 25 mg weekly up to a maximum dose of 100 mg administered in two divided doses.

Patients should maintain an adequate fluid intake in order to minimize the risk of kidney stones.

DRUG INTERACTIONS: The following medications, when taken with topiramate, increase the risk of kidney stones and metabolic acidosis: acetazolamide (Diamox), dorzolamide (Trusopt), methazolamide (Neptazane), dichlorphenamide (Daranide).

Carbamazepine (Tegretol) and phenytoin (Dilantin) markedly decrease the amount of topiramate in the body by increasing its elimination from the body. As a result, topiramate may lose effectiveness unless doses are increased.

Combining valproic acid (Depakote, Depakote ER, Depakene, Depacon, Stavzor) with topiramate may increase the blood ammonia levels and cause hypothermia.

Topiramate may decrease the amount of estrogen in the body in women taking oral contraceptives, possibly increasing the chances of unwanted pregnancy and breakthrough bleeding.

Patients with seizure disorders taking anticonvulsant medications, including topiramate, may develop nerve toxicity from a chemical, 4'-O-methylpyridoxine, found as a contaminant in some ginkgo preparations.

Medically Reviewed by a Doctor on 12/26/2014


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