A medication known as Namenda (memantine), an N-methyl D-aspartate (NMDA) antagonist, is prescribed to treat moderate to severe Alzheimer’s disease. This drug’s main effect is to delay progression of some of the symptoms of moderate to severe Alzheimer’s. It may allow patients to maintain certain daily functions a little longer than they would without the medication. For example, Namenda may help a patient in the later stages of the disease maintain his or her ability to use the bathroom independently for several more months, a benefit for both patients and caregivers.
Namenda is believed to work by regulating glutamate, an important brain chemical. When produced in excessive amounts, glutamate may lead to brain cell death. Because NMDA antagonists work very differently from cholinesterase inhibitors, the two types of drugs can be prescribed in combination.
Namenda was approved in October 2003 by the Food and Drug Administration for the treatment of moderate to severe Alzheimer's disease. The approval was based partly on a rigorous 28-week study of 252 people who were randomly chosen to receive the drug or a placebo. The results, published in the prestigious New England Journal of Medicine in the spring of 2003, showed that the drug could slow the downward spiral of the disease.
Namenda is proven to help treat the symptoms of moderate to severe Alzheimer's disease. That is important because the longer symptoms are treated, the more quality time you may have to spend with the person with Alzheimer's disease who you are caring for.
In a 28-week study, mentioned earlier, published in the New England Journal of Medicine patients suffering from moderate to severe Alzheimer's disease received either 20 mg of Namenda per day or a placebo (sugar pill). The study found that compared to patients taking placebo:
- Patients taking Namenda experienced a slower rate of decline in thinking over time.
- Namenda treated patients had significantly greater ability to perform daily activities, including doing household tasks such as taking out the garbage or clearing the table after dinner, as well as conversing.
Namenda in combination with donepezil may do more to treat the symptoms of moderate to severe Alzheimer's disease then donepezil alone.
Since so far there is no cure for Alzheimer's disease, the goal of treatment with Namenda, as with all Alzheimer's disease medications, is to treat the symptoms of Alzheimer's disease. Once treatment is started, you may wonder how long it will take for Namenda to have an effect. Some patients have seen an improvement within twelve weeks of starting therapy, although individual results may vary.
Please keep in mind that either no change in Alzheimer's disease symptoms or a slower rate of progression of symptoms are positive results compared to the more rapid decline a person with Alzheimer's disease might experience without treatment. It is important to understand that every day symptom progression is delayed may allow the person with Alzheimer's disease to spend more quality time with his or her loved ones.
How it works?
Namenda works in a unique way and is different from other prescription medications approved to treat Alzheimer's disease. As the only NMDA receptor antagonist, Namenda targets a brain chemical known as glutamate. Nerve cells rely on a variety of chemical messengers to transmit messages from one cell to the next. One of those chemical messengers is glutamate.
Glutamate is a chemical in the brain that has been associated with learning and memory. Abnormal glutamatergic activity in the brain may lead to Alzheimer's disease symptoms. Namenda may help block abnormal glutamatergic activity to improve symptoms.
Other Alzheimer's disease medications, known as AChEIs (acetylcholinesterase inhibitors), such as Aricept (donepezil), work by targeting a different brain chemical called acetylcholine. When there is too little acetylcholine in the brain of a person with Alzheimer's disease, memory and learning can be affected. AChEIs work by addressing that problem.
Taking Namenda alone or in combination with donepezil may help improve quality of life for people with Alzheimer's disease and their caregivers. There is no evidence that Namenda prevents or slows neurodegeneration in patients with Alzheimer's disease.
Therapy begins at a low dose (5 mg per day) and is gradually increased until the recommended target dose (10 mg, twice daily) is reached. A common dosing schedule for beginning Namenda therapy is provided below:
Recommended Namenda dosing schedule
- Week 1: Start on Day 1
Take one 5 mg tablet in the morning, each day.
- Week 2: Start on Day 8
Take one 5 mg tablet in the morning and one 5 mg tablet at night, each day.
- Week 3: Start on Day 15
Take one 10 mg tablet in the morning and one 5 mg tablet at night, each day.
- Week 4: Start on Day 22
Take one 10 mg tablet in the morning and one 10 mg tablet at night, each day.
- Once the recommended target dose (10 mg, twice daily) has been reached, people taking Namenda can continue with that daily regimen unless instructed otherwise by their doctors (For patients with severe renal impairment, 5 mg twice daily is the recommended dose).
Although generally well-tolerated, the most common side effects are dizziness, headache, constipation, and confusion. Unlike cholinesterase inhibitors such as Aricept, Exelon, and Razadyne, those taking Namenda have a low risk of gastrointestinal side effects.
Namenda has a low potential for drug interactions. However, other NMDA antagonist medications, which include some cold and flu medications (like dextromethorphan), should be used with caution while taking Namenda. Sometimes, doctors prescribe Namenda along with a cholinesterase inhibitor to treat moderate Alzheimer's disease, as some studies have shown additional benefit from combining these medications.
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