Memantine is a derivative of the decades old anti-influenza drug amantadine. Memantine is used in Germany to treat Parkinson's disease, dementia in the elderly, and to speed the recovery of comatose patients. Memantine may also be useful for PWAs with HIV encephalopathy (which can mean anything including memory loss, confusion, difficulty speaking, walking, and/or concentrating).
While some PWAs have been using memantine, and the AIDS Clinical Trial Group is currently planning to study it, at present there is no data from any clinical study in PWAs. We'll keep you posted on upcoming trials. Since there is no proven treatment for HIV-related neurologic problems, the PWA Health has decided to import memantine for any PWA with a doctor's prescription.
While the root cause of neurologic problems in PWAs is different from what causes Parkinson's or dementia in the elderly, people with these problems all lose neurons, the key brain or nerve cell, in much the same way. (PWAs with encephalopathy can lose up to 20-50% of their neurons.) How does this happen? Much of what we know comes from experience in Parkinson's disease. As the theory goes, too much of certain amino acids in the brain send signals to neurons that make them self-destruct. Memantine keeps to a minimum the destructive signals that neurons receive. These amino acids may be elevated in some PWA's too. What's worse, test tube and animal studies show that the HIV protein gp120 can also send neurons self-destruct signals. But until we know to what extent HIV related neurologic disorders are caused by these signals, we can't predict how helpful memantine will be in PWAs. If the theory is correct, another drug being studied in PWAs for neurologic problems, nimodipine, may increase the effect of memantine. With a prescription you can get nimodipine from a pharmacy, but it is very expensive, and since it isn't approved for this purpose, your insurance may not want to pay for it.
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We don't know the best dose for PWAs. In other groups, doses range from 5-60 mg a day, depending on the condition that it is being used for. 10-30 mg a day seems to be the standard maintenance dose in patients with Parkinson's disease. Since there isn't much information on the use of memantine in PWAs, it may make sense to start at a low dose, such as 5 mg a day (see below).
Memantine is fairly well tolerated in the elderly. One study noted a few cases of restlessness, insomnia and nervous energy (such as pacing, fidgeting). An open label study in fourteen patients with Parkinson's using 30 mg/day reported that four (28%) of these patients quit memantine because of nervous energy, emotional agitation, confusion, dizziness and stomach upset.
One doctor who has monitored some PWAs using memantine reports no serious side effects. She starts patients at a low dose, watches for adverse reactions and then gradually increases the dose. A number of PWAs have safely used related drugs, such as amantadine and Flumadine, which may bode well for the use of memantine. Even so, since there have been no clinical trials using memantine in PWAs, be very careful if you decide to take this drug. The potential for adverse or unexpected side effects for this kind of drug might be much greater in PWAs. Let your doctor know immediately of any adverse reaction, such as feeling like you want to climb the walls, emotional agitation, headaches, stomach aches and changes in mucous secretions, sweating, or any other sign of body dehydration.
Be extra careful if you are on any antidepressants such as Prozac or Zoloft since memantine may effect the way they work. You might be extra prone to hyperactivity or "manic" states if you take these drugs together. There could be a dangerous interactions between memantine and MAO inhibitors (including phenelzine sulfate, pargyline hydrochloride and methylclothiazide, furazolidone, isocarboxazid, procarbazine and tranylcypromine). If you are taking any of these start at a low dose of memantine. If you have ever had seizures you should be cautious with memantine. Data from animal studies suggest that very high doses of memantine could make seizures worse.
The PWA Health Group carries Akatinol brand memantine made by Merz Pharmaceuticals in Germany. It comes in boxes of 50 x 10 mg tablets (which can be split in half for patients who wish to start at 5 mg a day).
The PWA Health Group can help you import memantine from Germany. To order it from us, you must have your doctor write a prescription.