A mysterious loss of memory
Mrs. K develops depressive symptoms and memory loss while being successfully treated for multiple sclerosis and migraines. How would you address her cognitive decline?
Memantine has been reported to successfully treat other MS symptoms. A 1997 retrospective study found that 11 patients with acquired pendular nystagmus (APN) secondary to MS experienced complete resolution of APN when given memantine.17
Memantine was FDA-approved in 2003 to treat moderate-to-severe Alzheimer’s disease dementia. The drug also has been used off-label to treat vascular dementia, dementia of Wernicke-Korsakoff syndrome, and acquired pendular nystagmus.11
Although the neurobiologic basis for memantine’s therapeutic activity in patients with dementia is not fully understood, it is thought to reduce glutamatergic excitotoxicity. The mechanism of action is voltage-dependent, uncompetitive N-methyl-D-aspartate (NMDA) receptor antagonism with low-to-moderate affinity and fast blocking/unblocking kinetics.12 Its kinetic profile is beneficial because it allows memantine to occupy the receptor for a sufficient time to prevent pathologic activation of glutamate receptors. However, it dissociates when the physiologic activation of glutamate receptors is necessary, thus preserving normal NMDA receptor activity required for learning and memory. By blocking the effects of abnormal glutamate activity, memantine may prevent abnormal neuronal cell death and cognitive dysfunction.
- Parsons CG, Stöffler A, Danysz W. Memantine: a NMDA receptor antagonist that improves memory by restoration of homeostasis in the glutamatergic system—too little activation is bad, too much is even worse. Neuropharmacology. 2007;53(6):699-723.
- Alprazolam • Xanax
- Amitriptyline • Elavil
- Budesonide • Rhinocort
- Butalbital/Aspirin/Caffeine • Fiorinal
- Conjugated Estrogens • Premarin
- Esomeprazole • Nexium
- Eszopiclone • Lunesta
- Famotidine • Pepcid
- Fexofenadine • Allegra
- Interferon beta-1b • Betaseron
- Levothyroxine • Synthroid
- Memantine • Namenda
- Propranolol • Inderal
- Rizatriptan • Maxalt
- Topiramate • Topamax
Dr. Rao is a speaker for Forest Pharmaceuticals.
Acknowledgement
The author thanks Alexander M. Timchak, MS-IV, Stritch School of Medicine, Loyola University, Chicago, for his assistance with this article.
