Up to one-third of patients with mild to moderate Alzheimer's disease may show 
improvement in cognitive function with tacrine, a centrally-acting, 
noncompetitive inhibitor of acetylcholinesterase. Candidates for tacrine must 
have a diagnosis of probable Alzheimer's dementia based on NINCDS-ADRDA or 
DSM-IV criteria and should have no history of liver disease. For patients 
receiving the drug, do follow-up cognitive testing with a sensitive measure such 
as the Alzheimer's Disease Assessment Scale. The most common adverse effects 
associated with tacrine therapy are elevated liver transaminases and 
gastrointestinal effects. Weekly blood tests are necessary to monitor liver 
function. A reliable caregiver is essential to ensure compliance with frequent 
dosing and weekly blood testing.