Making sense of the Alzheimer's drug pipeline
Alzheimer's disease is a thief. It robs seniors of a lifetime of experience and memories as it also robs their children and other loved ones of the benefits of their wisdom. It empties the wallets of families, and leaves many emotionally drained at seeing their elders slowly disappear into themselves.
According to the Alzheimer's Association, deaths attributed to the disease have increased by more than 46 percent between 2000 and 2006. Today, in the United States alone, 5.3 million people have Alzheimer's disease, and its annual cost is $172 billion. It is the sixth leading cause of death, and mortality rates are expected to rise as the baby boomer population ages.
So, what new answers has medical science has come up with? At best, it's good news and bad news. First, the bad news: there is no cure. There is not even complete agreement as to its cause. There is a general consensus that extracellular amyloid-beta (Aß) plaques and intraneuronal tangles in the brain are to blame. Drugs being developed tend to target these plaques. But, at best, they hold off symptoms temporarily.
Now, the good news. Biomarkers research is making it increasingly possible to determine whether a person might develop Alzheimer's disease, perhaps even decades in advance. The earlier the disease is detected, the better the chances are of being able to delay its symptoms or at least prepare for them. It could be argued, however, that this detection capability is, in itself, a good news/bad news scenario.
But, those sticky philosophical issues aside, medical progress marches on in its usual lurching way--many failures mixed with some progress. Here's a rundown of what's on the market, recent drug failures, pipeline prospects and the most recent research from the the laboratory trenches.
On the Market
- Galantamine (Razadyne, Nivalin)
This medication is among a class of Alzheimer's drugs called cholinesterase inhibitors, which are prescribed for mild to moderate symptoms. Razadyne is marketed by Ortho-McNeil Janssen Pharmaceuticals. Sopharma, based in Bulgaria, markets Nivalin primarily in Eastern Europe. The Indian pharmaceutical company Sun Pharmaceutical Industries recently received the FDA OK to sell a generic version of galantamine in the United States. The drug helps delay symptoms, or prevents them from becoming worse, for a limited time.
- Rivastigmine (Exelon)
Exelon is marketed by Novartis, although there are generic equivalents, including those marketed by Sandoz and Sun Pharmaceuticals. It is used to treat mild to moderate dementia due to Alzheimer's. Rivastigmine, too, is a cholinesterase inhibitor. One of many things Alzheimer's does to the brain is decrease the levels of acetylcholine, which is a chemical messenger tied to memory. Cholinesterase inhibitors improve the effectiveness of acetylcholine. Unfortunately, since the brain produces less acetylcholine as Alzheimer's progresses, medications like rivastigmine can lose their effectiveness over a period of time.
- Donepezil (Aricept)
According to the Mayo Clinic, Donepezil is among the most prescribed of the cholinesterase inhibitors and was the first to offer once-a-day dosing. It is also the least likely to produce serious side effects, the Mayo Clinic says, and appears to temporarily postpone the development of Alzheimer's in people with mild cognitive impairment (MCI), a memory-related condition that may precede Alzheimer's. Donepezil is marketed under the name Aricept Japanese drugmaker Eisai and partner Pfizer. The FDA is now taking a look at a patch form of Aricept by Teikoku Pharma USA. Aricept is among 2010's biggest patent expirations, and Roxane, Apotex and Aurobindo all have submitted ANDAs for multiple strengths of the drug.
- Memantine (Namenda)
Memantine, marketed under the brand name Namenda, helps delay the progression of some symptoms associated with moderate to severe Alzheimer's, allowing patients to maintain some functions--like using the bathroom independently--a little longer. Namenda works by regulating glutamate, a brain chemical that can kill brain cells if an excessive amount builds up. Because it works differently than cholinesterase inhibitors, the two types of drugs can be prescribed in combination. Generally, Namenda is prescribed in later stages of Alzheimer's. The drug is marketed in the United States by Forest Laboratories and Merz Pharmaceuticals. A generic version of Namenda is marketed in the United States by Sun Pharmaceuticals.