Frequently asked questions about Topiramate, used for treatment of mood disorders -mania and depression- and PTSD.
NOTE: Topiramate (Topamax) is only approved for the treatment of people with seizures. There are few systematic studies that establish the safety or efficacy of topiramate as a treatment for people with mood disorders or PTSD. While such studies are underway, what is currently known about the use of topiramate for the control of mood disorders and PTSD comes mostly from uncontrolled case reports.
1. What is topiramate (Topamax)?
Topiramate is an anticonvulsant that is chemically unrelated to any other anticonvulsant or mood regulating medication. The mechanism of action is unknown.
2. When was topiramate approved for marketing in the USA and for what indications may it be promoted?
Topiramate received final approval for marketing in the USDA on 24 December 1996 and is labeled for use as an anticonvulsant.
3. Is a generic version of topiramate available?
There is no generic topiramate as the manufacturer has patent protection.
4. How does topiramate differ from other mood stabilizing drugs?
Topiramate differs from other mood stabilizing drugs in two major ways:
- topiramate's frequent effectiveness for patients who have failed to respond to antidepressants or mood stabilizers;
- topiramate's unique side-effect profile.
5. What, if anything, uniquely distinguishes topiramate from carbamazepine and valproate?
6. People with what sorts of disorders are candidates for treatment with topiramate?
It is too early to be very specific about which mood disorders are most likely to respond to treatment with topiramate. There are just about no published reports on topiramate's use in psychiatry. Patients with hard-to-treat bipolar syndromes have been treated more often than patients with "treatment-resistant" unipolar disorders.
Topiramate seems especially useful when it comes to treating people who have become manic as the result treatment with lamotrigine.
There has recently been a report regarding the control of the symptoms of PTSD by topiramate.
7. Is topiramate useful for the treatment of acute depressed, manic and mixed states, and can it also be used to prevent future episodes of mania and/or depression?
The initial use of topiramate was to treat people with depressed, manic rapid-cycling, and mixed states that did not respond to existing medications. Some patients are now being maintained on topiramate on a long term basis in an attempt to prevent future episodes. The effectiveness of topiramate as a long-term prophylactic agent is currently being established.
8. Are there any laboratory tests that should precede the start of topiramate therapy?
Before topiramate is prescribed the patient should have a thorough medical evaluation, including blood and urine tests, to rule out any medical condition, such as thyroid disorders, that may cause or exacerbate a mood disorder.
9. How is treatment with topiramate initiated?
Topiramate is usually initially prescribed at an initial dose of 12.5 -25 mg once or twice a day and the total daily dose is increased by 12.5 - 25 mg every week. When prescribed in addition to other anticonvulsants being used as mood stabilizers, the final dose is often between 100 and 200 mg per day. Some patient with Bipolar Disorder do well on as little as a total daily dose of 50 mg/day. When used for the control of the symptoms of PTSD the average final dose is about 175 mg/day (with a range of 25 - 500 mg/day).
10. Are there any special problems prescribing topiramate for people taking lithium, carbamazepine (Tegretol), or valproate (Depakene, Depakote)?
Carbamazepine and valproate both have the ability to lower plasma levels of topiramate . . . carbamazepine by about 50% and valproate by about 15%. Topiramate has no effect on the plasma level of carbamazepine but can reduce the plasma level of valproate by about 10%. Pharmacokinetic interactions between topiramate and either lamotrigine (Lamictal) or gabapentin (Neurotin) have not been reported.
11. What is the usual final dose of topiramate?
When used as a mood-stabilizing agent the final dose of topiramate is most often between 50 and 200 mg/day. Some people require doses as high as 400 mg/day to achieve a good mood stabilizing effect . . . especially when topiramate is being used as a monotherapy . . . while others do fine on 25 mg/day.
12. How long does it take for topiramate to 'kick-in?'
While some people notice the antimanic and antidepressant effects early in treatment, others have to take a therapeutic amount of topiramate for up to a month before being aware of a significant amount of improvement.