Serious side effects of Topamax
Most people who take Topamax (topiramate) have no side effects or only mild or moderate side effects without sequelae. No fatal reactions have been associated with its use.
Certain circumstances predispose patients to acidosis:
Acidosis usually occurs early in treatment but can arise at any time. Physicians are advised to measure baseline serum bicarbonate before initiating treatment and to test levels periodically.
Metabolic acidosis can cause symptoms such as fatigue, loss of appetite, irregular heartbeat, and impaired consciousness. Patients should be advised to contact their doctor or other health care provider if these symptoms develop while taking topiramate.
Chronic, untreated acidosis may lead to conditions such as kidney stones, osteomalacia, or osteoporosis and may reduce growth rate (and maximal height) in pediatric patients.
If acidosis persists, discontinuation of Topamax or the addition of alkali treatment should be considered.
Psychiatric side effects
A study of 431 patients in England found that 103 (nearly 24%) had some kind of psychiatric effect (Mula 2003). This included 16 people (4%) with psychosis, 24 with aggressive behavior, 17 with other behavior abnormalities, and 46 with a mood disorder.
Another report of 91 patients in England found symptoms of psychosis in 12%, compared to less than 1% of patients who took Neurontin (gabapentin) or Lamictal (lamotrigine) (Crawford 1998). Seven patients (8%) were admitted to the hospital because of psychosis or depression.
Another group of doctors looking only for symptoms of psychosis found them in 5 (6%) of the first 80 patients they treated with Topamax (Khan 1999).
Most reports have indicated that people with a history of psychiatric illness are much more likely than others to experience psychiatric disorders while taking Topamax (Mula 2003, Trimble 2000). The disorder tends to be of the same type as before. That is, those who have had psychosis in the past are more likely to experience symptoms of psychosis again, and those with past mood disorders are more likely to have a similar mood disorder (Trimble 2000). People with no history of psychiatric disorders also can be affected, however (Khan 1999).
Other factors that have been implicated in the development of psychiatric side effects from Topamax are:
On the other hand, it has been reported that psychiatric side effects are less likely in people with a low frequency of seizures before starting Topamax and in those also taking Lamictal. (Mula 2003)
On July 10, 2008, an advisory panel was convened by the Food and Drug Administration (FDA) to review data that the FDA had previously collected from drug studies showing an association between many of the antiepileptic drugs (AEDs) and suicidal ideation and behavior, which together are called suicidality. According to the FDA’s Alert, among the patients with epilepsy in these drug studies, 1 out of 1000 people taking the placebo (inactive substance) showed suicidality compared to approximately 3.5 out of 1000 people who took an AED. The FDA advisory panel voted to accept the FDA's data at its meeting on July 10. The FDA has provided the following information for patients, family members, and caregivers at www.fda.gov/cder/drug/InfoSheets/HCP/antiepilepticsHCP.htm.
We again urge patients and families to contact their doctor before stopping an epilepsy medication because this may possibly lead to seizures and worsening of mood.
Reviewed July 2008 by Steven C. Schachter, MD, epilepsy.com Editorial Board.
When a patient presents with a serious and/or unexpected adverse reaction from a medication or device, you should consider reporting this event to Medwatch (http://www.fda.gov/medwatch/report/hcp.htm). To download Medwatch reporting forms click here (http://www.fda.gov/medwatch/getforms.htm).Back to top
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