Consumer Reports compares and analyzes 12 anticonvulsants

PR Newswire

WASHINGTON, Sept. 5 -- Some anticonvulsant drugs are effective in treating bipolar disorder, fibromyalgia, and various kinds of pain, but the widely prescribed drugs are not always the best initial choice to treat those conditions and some of the drugs are quite expensive, according to the latest report from Consumer Reports Best Buy Drugs, a public information project of Consumers Union.

The report -- written for consumers and available free at http://www.crbestbuydrugs.org/ -- compares and analyzes 12 anticonvulsants. Scientific evidence backs only a few in treating the three disorders. That is significant because many of the 12 drugs are commonly prescribed "off label" to treat mental health and pain problems.

"This is a case where a class of drugs is widely used off-label to treat millions of Americans with assorted types of pain, emotional distress, and mental health problems," says Gail Shearer, project director of Consumer Reports Best Buy Drugs. "But the evidence is either weak or non-existent that some of them help people or are the best drugs to use. Doctors and patients should be more cautious and deliberative in using these drugs," she added.

The anticonvulsants are also known as anti-epileptics. They were designed -- and are approved by the Food and Drug Administration -- primarily to treat people who have various kinds of seizure disorders, including seizures or convulsions caused by epilepsy, strokes, and brain tumors. Several -- phenytoin (Dilantin), carbamazepine (Carbatrol, Tegretol,), ethotoin (Peganone), and valproic acid/divalproex (Depakene/Depakote) -- have been on the market since the 1950s. But a "second generation" of anticonvulsants was developed in the 1990s. These include gabapentin (Neurontin), lamotrigine (Lamictal), pregabalin (Lyrica) and topiramate (Topamax).

Both the old and new anticonvulsants -- but especially the new ones -- gained traction through the 1990s in treating pain and mental disorders. They all affect the central nervous system. In particular, the drugs are now prescribed often to treat nerve pain, or neuralgia, caused by damage or trauma to the nerves or parts of the nervous system. Nerve pain occurs in many people who have diabetes, for example, which damages nerves and blood vessels. Cancer can also cause nerve pain, as can chemotherapy to treat cancer. Some infections can also cause nerve pain, including HIV. And shingles is a form of intense nerve pain caused by the herpes zoster virus -- affecting over a million people each year.

The report notes that the FDA has now approved several anticonvulsants to treat conditions other than seizures. Namely, divalproex, lamotrigine (Lamictal), and carbamazepine have been approved to treat the manic phases of bipolar disorder; carbamazepine, gabapentin (Neurontin), and pregabalin (Lyrica) have been approved to treat various forms of nerve pain; and pregabalin (Lyrica) was just recently (in June 2007) approved to treat fibromyalgia -- an often chronic condition characterized by muscle pain or soreness, joint tenderness or pain, fatigue, and a chronic, low-grade flu-like feeling.

The report presents evidence supporting those uses, but also cautions that other treatments may sometimes work better or be a better initial choice for some patients. In addition, it presents detailed information on the adverse side effects of the drugs, noting in particular that the newer drugs pose the same level of risk (albeit different risks) as the older drugs.
The report presents detailed cost information on the drugs as well, noting that the newer anticonvulsants can be quite expensive ($300 a month and up), and are generally more costly than the older drugs. However, some of the newer drugs (most notably gabapentin) are now available as lower-cost generics, too.

Taking cost, dosing convenience, and the evidence for effectiveness and adverse effects into consideration, the report chooses the following drugs as Best Buys:

-- Generic carbamazepine -- for treating the mania phase of bipolar disorder or trigeminal neuralgia, a type of nerve pain that affects facial nerves

-- Generic valproic acid -- for treating the mania phase of bipolar disorder

-- Lamotrigine (Lamictal) -- for treating both the mania and depressive phases of bipolar disorder

-- Generic gabapentin -- for treating the nerve pain associated with diabetes or herpes zoster infection (shingles)

-- Pregabalin (Lyrica) -- for treating the nerve pain associated with diabetes or herpes zoster infection (shingles)

The anticonvulsant report is the 19th in a series helping consumers find effective and safe medicines that give them the most value for their health-care dollar. Other reports compare medicines to treat depression, high blood pressure, diabetes, heartburn, high cholesterol, heart disease, asthma, allergies, and overactive bladder.

Consumer Reports Best Buy Drugs(TM) combines a review of the scientific evidence on the effectiveness and safety of medicines with pricing information. Every report is peer-reviewed by medical experts. The project is independently administered by Consumers Union and Consumer Reports with support from the Engelberg Foundation, a private philanthropy, and the National Library of Medicine.

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