Antiepileptic drugs (AEDs) are used to treat various nonepileptic neuropsychiatric disorders such as bipolar disorders, trigeminal neuralgia, migraine, and Parkinson's disease. Since gabapentin (GBP) was released in 2006, nearly 10 new types AEDs have been approved for use one after another in Japan. However, but it is unclear which AEDs are indicated for use in patients with nonepileptic conditions or off-label use. In addition, the research supporting such uses is unclear.
 Therefore, I examined the adaptation and off-label use of new AEDs in patients with nonepileptic conditions by psychiatrists in Japan, the United States, and Europe.
 In the psychiatric setting, carbamazepine, sodium valproate, and lamotrigine are indicated for bipolar disorder in various countries, and pregabalin, which is a derivative of GBP, is approved for generalized anxiety disorder in Europe. However, other AEDs are not approved for psychiatric disorders, and the above-mentioned AEDs are used off-label for other psychiatric disorders. The off-label use of antiepileptic drugs includes the use of levetiracetam to improve cognitive function in early Alzheimer's disease and schizophrenia, and the use of perampanel in patients with amyotrophic lateral sclerosis. These trials are still ongoing, and their results are expected.
  Pharmaceutical companies have adopted the strategy of first selling new drugs for the treatment of central nervous system conditions as AEDs and then aiming to expand the indication for chronic diseases with large numbers of patients, such as bipolar disorder and neuropathic pain. It is thus expected that companies will continue to take various approaches to encourage clinicians to use AEDs off-label.
  The off-label use of antiepileptic drugs in psychiatric clinics leads to the following three problems: 1) medical problems, as there is a possibility that the risk of adverse events may increase due to prolonged polypharmacy, 2) institutional problems, as off-label use is outside the scope of the drug side effect relief system, and 3) health economic issues, as off-label use is treated as free medical treatment and other treatments that are originally indicated by health insurance will not be accepted. Based on the background and problems of off-label AED use, as described above, we should carefully consider off-label use of AEDs for nonepileptic conditions.
 ＜Author's abstract＞