Table 1.

Currently available prescription drugs for treatment of different stages of Alzheimer’s disease

Drug	Prescribed for Alzheimer’s disease stage(s)	Mechanisms of action	Beneficial effects	Side effects
Donepezil (Aricept®)	All stages	It is a cholinesterase inhibitor that inhibits breakdown of acetylcholine in the brain.	As the drug maintains acetylcholine levels, it improves brain functioning, memory, and thinking and may delay or slow worsening of symptoms.	It causes nausea, vomiting, diarrhea, muscle cramps, fatigue, weight loss, and appetite loss.
Rivastigmine (Exelon®)	Mild to moderate	It is a cholinesterase inhibitor that prevents breakdown of acetylcholine and butyrylcholine in the brain.	As the drug maintains acetylcholine levels, it improves brain functioning, memory, and thinking and may delay or slow worsening of symptoms.	It causes nausea, vomiting, diarrhea, weight loss, appetite loss, indigestion, and muscle weakness.
Galantamine (Razadyne®)	Mild to moderate	It is a cholinesterase inhibitor that inhibits breakdown of acetylcholine but stimulates nicotinic receptors to release more acetylcholine in the brain.	As this drug stimulates release of acetylcholine, it strengthens the nerve cells to respond to certain messages.	It causes nausea, vomiting, diarrhea, decreased appetite, dizziness, and headache.
Memantine (Namenda®)	Moderate to severe	It is a N-methyl D-aspartate antagonist that prevents toxic effects of excess glutamate.	It shows significant improvement in mental functioning and ability to perform daily activities.	It causes dizziness, headache, diarrhea, confusion, and constipation.