Two cases of loss of consciousness after long-term memantine treatment.

Memantine is approved for treatment of moderate to severe Alzheimer disease (AD) but is also investigated as a treatment option for a number of different conditions, and even though there are reports of a number of adverse effects, including new-onset seizures and psychosis, it is considered to be generally well tolerated. We report two cases of repeated loss of consciousness after long-term memantine treatment in patients with AD, which resolved after its discontinuation. The possible changes in the central nervous system after prolonged memantine use for AD are briefly discussed, as well as its capacity to facilitate and/or change the expression of seizure activities. Presented cases indicate the need for increased caution and careful weighing of benefits and risks of prolonged treatment with memantine in patients with AD, as well as for careful evaluation of risks of combining memantine with other medications.