Donepezil hydrochloride (Aricept - Eisai), a piperidine-based acetylcholinesterase inhibitor, is now being marketed for oral treatment of cognitive symptoms in patients with mild to moderate dementia due to Alzheimer's disease. Donepezil is the second drug approved for this indication; tacrine hydrochloride (Cognex), also an acetylcholinesterase inhibitor, has been available in the USA for four years (Medical Letter, 35:87, 1993).

The FDA has approved Namzaric (Forest), a fixed-dose combination of extended-release (ER) memantine (Namenda XR), an NMDA-receptor antagonist, and donepezil (Aricept, and generics), an acetylcholinesterase inhibitor, for treatment of moderate to severe Alzheimer's type dementia in patients previously stabilized on both drugs. The patent for Namenda has recently expired and generic formulations of memantine 5- and 10-mg tablets have been approved.

Rivastigmine tartrate (Exelon - Novartis), a carbamate-based cholinesterase inhibitor, is now being marketed for treatment of patients with dementia due to Alzheimer's disease.

Galantamine hydrobromide (Reminyl), a tertiary alkaloid and phenanthrene derivative extracted from daffodil bulbs, is now being marketed for oral treatment of mild to moderate Alzheimer's disease. Galantamine is the fourth acetylcholinesterase inhibitor approved for this indication.

A once-weekly transdermal formulation of the acetylcholinesterase inhibitor donepezil (Adlarity – Corium) has been approved by the FDA for treatment of mild, moderate, and severe Alzheimer's disease (AD) dementia. Donepezil is the second acetylcholinesterase inhibitor to become available in a transdermal formulation; transdermal rivastigmine (Exelon Patch), which is applied once daily, has been available for years for the same indication. Donepezil is also available in oral formulations (Aricept, and generics) for treatment of AD dementia.

Memantine hydrochloride, which has been used to treat dementia in Germany (Axura Merz) since 1982, has become the latest word-of-mouth miracle drug for Alzheimer's disease in the US (G Kolata, NY Times, June 15, 2003). Forest Laboratories has submitted a New Drug Application to the FDA for memantine. This review describes the standard treatment for Alzheimer's Disease, mechanism of action, clinical studies, adverse effects and dosage. Also included are sections on availability of the drug and how some people are obtaining memantine from abroad.

Cholinesterase inhibitors are now used routinely in patients with dementia. Rivastigmine transdermal system (Exelon Patch - Novartis), a patch formulation of the cholinesterase inhibitor rivastigmine tartrate, has been approved by the FDA for treatment of mild to moderate dementia associated with Alzheimer's or Parkinson's disease. An oral formulation of rivastigmine tartrate has been available in the US since 2000,2 but gastrointestinal adverse effects possibly related to rapidly rising serum concentrations have limited its use.

View the Comparison Table: Drugs for Alzheimer's Disease

Solifenacin succinate (VESIcare - Yamanouchi and GlaxoSmithKline) and darifenacin hydrobromide (Enablex - Novartis) have been approved by the FDA for oral treatment of overactive bladder.

Alzheimer's disease (AD) is the most common cause of dementia, but cognitive decline is also associated with other neurological conditions such as Parkinson's disease, dementia with Lewy bodies, vascular dementia, and frontotemporal dementia.