Table 1. Cholinesterase Inhibitors and Memantine for the Treatment of Cognitive Deficits in Patients with Alzheimer Disease (AD)6,59
DrugApproved IndicationSuggested DosageSide EffectsAdditional Notes/Caution
Cholinesterase inhibitors
    Donepezil (Aricept)Mild to moderate ADOnce daily, beginning with 5 mg/day, which can be increased to 10 mg/day (maximum dosage) after 4 weeksAEs are mild and include nausea, vomiting, and diarrheaGastrointestinal-related AEs can be reduced if medication taken with food
Some patients exhibit an initial increase in agitation, which subsides after first few weeks of therapy
Severe AD
    Rivastigmine (Exelon)Mild to moderate ADOral: Twice daily, beginning with 1.5 mg
Transdermal patch: Once daily, 4.6 or 9.5 mg
The target dose is 9.5 mg/24 hr per patch (a 10 cm2 patch) and requires a simple one-step dose titration to the therapeutic dose
There is a higher-dose patch (20 cm2) available, delivering 17.4 mg/24 hr; however, it is currently an unapproved treatment in the United States. Lack of approval was based on it having similar efficacy to the 10 cm2 patch, but with a tolerability profile comparable to that of the capsule formulation
AEs include nausea, vomiting, diarrhea, weight loss, headaches, abdominal pain, fatigue, anxiety, and agitation
Gastrointestinal-related AEs are less prominent with the patch: the 9.5 mg/24 hr patch provides efficacy similar to that of the highest dose of capsules, with 3 times fewer reports of nausea and vomiting
Higher dosages are more efficacious than lower dosages
No laboratory monitoring is required
    Galantamine (Razadyne)Mild to moderate ADTwice daily, beginning with 4 mg
After 4 weeks, dosage is increased to 8 mg twice daily
An increase to 12 mg twice daily can be considered on an individual basis after assessment of clinical benefit and tolerability
Also available in an extended-release formulation that can be taken once daily
Most common side effects are nausea, vomiting, and diarrheaGastrointestinal-related AEs can be minimized by titrating the dosage gradually and taking the medication with meals
NMDA antagonist
    Memantine (Namenda)Moderate to severe ADTwice daily, beginning with 5 mg, increasing the dose to 10 mg twice daily over 3 weeksAEs include fatigue, pain, hypertension, headache, constipation, vomiting, back pain, somnolence, dizzinessModerate to severe AD may respond better with memantine/donepezil combination versus donepezil alone
  • AE, adverse event; NMDA, N-methyl D-aspartate.