<b>Mechanism of Action:</b>
Memantine also known as Namenda (memantine HCl) is the first of a new class of medications for Alzheimer's disease with a mechanism of action distinct from currently available drugs. Namenda is a low to moderate affinity NMDA (N-methyl-D- aspartate) receptor antagonist. It is thought that overexcitation of NMDA receptors by the neurotransmitter glutamate may play a role in Alzheimer's disease since glutamate plays an integral role in the neural pathways associated with learning and memory. The excitotoxicity produced by abnormal levels of glutamate is thought to be responsible for neuronal cell dysfunction and the eventual cell death observed in Alzheimer's disease. Namenda is thought to selectively block the excitotoxic effects associated with abnormal transmission of glutamate, while allowing for the physiological transmission associated with normal cell functioning.<br>
<b>What are the benefits of Memantine:</b> It is impossible to predict the potential benefits of Memantine for any particular person. Some people will improve, some will stay stable for a time, while others will continue to deteriorate. Data released by Lundbeck shows that Memantine is effective, but not universally, and that fewer people benefit as time passes. An early study showed that after 12 weeks, 73 per cent of patients were stable, or had improved. Another study showed that after six months, only 29 per cent continued to be stable, or had improved. However, the studies used different assessment scales and criteria, so it is probably unwise to draw too many conclusions.<br>
<b>Who does Memantine work for:</b> The action of Memantine is complex, especially when compared to the three existing treatments. It targets glutamate, which is a neurotransmitter. Neurotransmitters 'carry' electrical impulses from one brain cell to the next, across a space known as the synapse. Each nerve cell has a specific set of neuroreceptors responsible for 'receiving' glutamate from the neighbouring nerve cell. It is thought that during learning and when using memory, high levels of glutamate are released into the synapse. This opens up the neuroreceptors by removing a magnesium 'cover' from the opening of the neuroreceptor, and allowing glutamate to enter. The neuroreceptor responds by releasing calcium into the nerve cell. Because the background level of calcium in the cell is low, the new calcium is 'noticed' as a signal, which is then passed on to the next cell. In the brain cells of someone with Alzheimer's disease, glutamate is present at quite high levels when the cell is at rest, as well as during learning or when using memory. This means that the magnesium 'cover' on the neuroreceptor is permanently 'off'. With no cover on the neuroreceptor, calcium floods into the cell. There is then so much calcium in the cell that it doesn't 'notice' the addition of new calcium, and so ceases to recognise signals. Memantine effectively takes the place of magnesium as the 'cover' for the neuroreceptors. Unlike magnesium, Memantine isn't knocked off the neuroreceptor by the raised levels of glutamate present in Alzheimer's disease. This means that the cell is not flooded by calcium. When a learning or memory event occurs, the glutamate level rises enough to dislodge the Memantine 'cover', allowing calcium to enter and be 'recognised' as a signal. It is thought that the build-up of calcium in the cell could also contribute to premature cell death. Dying cells release glutamate in even greater amounts, and so the process of cell dysfunction and death is accelerated. For this reason, Memantine is thought to protect cells from excess calcium damage, and thus slow down the progress of the disease. The three other drugs for Alzheimer's have no effect on the disease process, and merely slow down the progression of symptoms. Taking Memantine top Memantine comes in two forms, as 10mg tablets, and as 10mg oral drops. The tablets can be broken in half into 5mg doses, and taken with or without food.
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<b>Memantine Dosage Instructions:</b>Here's the dosage that Lundbeck suggests for both the the tablet and oral drop forms: 1st week: 5mg once a day 2nd week: 10mg (5mg twice a day) 3rd week: 15mg (10mg in the morning, 5mg in the afternoon) 4th week onwards: 20mg (10mg twice a day) Lundbeck has recommended that Memantine should only be prescribed when there is a carer available to monitor usage.
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<b>Who can't take Memantine:</b> Memantine is not recommended for people with severe kidney problems, but only because there has been no safety test for this group as yet. Caution is recommended for people with epilepsy and heart problems.
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<b>Is Memantine used for other types of dementia:</b> Merz have released data showing that Memantine is also effective for people in the later stages of vascular dementia. However, the drug has been used for Alzheimer's disease. Remaining questions about Memantine top There is still a lot we don't know about Memantine, or about how it will be prescribed.