A Review of Seizure Medication Topiramate (TOPAMAX) for Weight Reduction

Internet advertisements are heavily promoting the use of topiramate (TOPAMAX), a prescription drug approved by the FDA only for the treatment of seizures, as a weight reduction agent, a purpose for which it has not been shown to be safe and effective. At the end of last December, the FDA required that topiramate’s manufacturer, the Ortho-McNeil Division of Johnson and Johnson, send a strong warning letter to doctors concerning the fact that topirimate has caused a very common and sometimes life-threatening abnormality in acid-base metabolism known as metabolic acidosis, in which the body becomes too acidic. Some of the adverse effects manifested in metabolic acidosis include hyperventilation, fatigue, cardiac arrhythmias, stupor, and kidney stones.

Another important and relatively common adverse effect seen with metabolic acidosis — obviously being exploited by Internet companies promoting topiramate for weight loss — is loss of appetite — anorexia. According to the Warning Letter, “the rate of occcurence of a persistently decreased serum bicarbonate (the abnormality in metabolic acidosis) ranges from 23-67% for patients treated with topiramate and 1-10% for placebo.....The incidence of a markedly abnormally low serum bicarbonate...was 11% for TOPAMAX and 0% for placebo”. Other consequences of metabolic acidosis include osteoporosis, change in mental status including speech and language difficulties and, in children, growth retardation. Although these abnormalities occurred in people being treated for seizure disorders, there is every reason to believe that they would occur as commonly in patients being treated for weight reduction. The new warning includes the recommendation that serum bicarbonate levels be monitored before and during treatment with topiramate.

Thus, it appears that a very common adverse effect, metabolic acidosis, is being used “therapeutically” by Internet topiramate-pushers because one of its symptoms, loss of appetite, is useful in losing weight. Like so many other now-discarded/banned weight loss drugs such as fenfluramine (one component of fen-phen), phenylpropanolamine (PPA), ephedra, and more like sibutramine (MERIDIA) to follow, the down-side of weight loss is the risk, especially high with topiramate, of serious adverse reactions. Another downside is that for none of these drugs is there evidence of long-term, sustained weight loss. So what is the point?

Other Adverse Effects of Topiramate

In the fall of 2001, neurologists, ophthalmologists, and other healthcare professionals were warned that FDA and Ortho-McNeil had strengthened the WARNINGS and PRECAUTIONS sections in the label of topiramate because of what are now more than 100 cases of glaucoma caused by the drug. These cases were characterized by ocular pain, acute myopia (near sightedness), and increased intraocular pressure, and were reported in pediatric and adult populations. The primary treatment is discontinuation of topiramate. If left untreated, serious consequences, including permanent vision loss, may occur. Patients taking topiramate should be told to seek immediate medical attention if they experience blurred vision or periorbital pain (pain around the eye socket). In addition, patients, especially pediatric patients, treated with TOPAMAX should be monitored closely for evidence of decreased sweating and increased body temperature, especially in hot weather.

What You Can Do

If you are using topiramate, be sure that there are no other safer drugs that can be used as a substitute. If you need to take the drug, be on the alert for early evidence of adverse effects including loss of appetite, nausea, hyperventilation, fatigue, change in mental status including speech and language difficulty, severe pain in the back or groin possibly indicating kidney stones, blurred vision, eye pain or acute development of nearsightedness, or, especially in children, decreased sweating and increased temperature. Call your doctor if any of these occur.