Adapted from IOS Press
In a study published this month in the Journal of Alzheimer's Disease, researchers from the University of Aberdeen report that the drug memantine, used for the treatment of Alzheimer's disease and praised as "the first and only representative of a new class of Alzheimer drugs" works in fact similar to other existing compounds, and is beneficial only in a narrow concentration range. They further indicate that the complex pharmacological profile of memantine requires careful consideration concerning suitable doses and suitable patient groups, so that the best use can be achieved for patients suffering from Alzheimer's disease.
In Alzheimer’s disease, two systems necessary for the communication of brain cells fail: The stimulatory brain messenger acetylcholine is down-regulated, while over-activation of the messenger glutamate leads to the death of neurons.
Memantine (trade names: Namenda™, Axura®, Ebixa®) was approved in 2002 by the European Agency for the Evaluation of Medicinal Products and in 2003 by the US FDA (Food and Drug Administration) for the treatment of moderate-to-severe Alzheimer’s disease. The arrival of this compound was greeted with great expectations since it could potentially be beneficial not only for Alzheimer’s disease, but also for other brain disorders that involve excess glutamate stimulation, such as trauma and stroke.
In the present study, researchers report that memantine has a much more complex pharmacological profile than originally described. It does in fact work rather similar to the originally introduced drugs that affect acetylcholine-related signaling, in addition to weak actions on glutamate, and has negative effects on neuronal communication at high concentrations. At lower concentrations, memantine was able to enhance signaling between neurons of the hippocampus (the main brain area affected in Alzheimer’s disease) and was indeed able to reverse learning and memory deficits. However, a pharmacological analysis showed that this was not due to its ability to block glutamate signaling, but rather to an additional and more potent action on the acetylcholine system.
Therefore, the investigators’ data do confirm that memantine shows promising aspects for the treatment of Alzheimer's disease, but only in a narrow concentration range. More importantly, its complex pharmacological profile requires careful considerations concerning suitable doses and suitable patient groups, so that the best use can be achieved for patients suffering from Alzheimer’s disease.