Cholinesterase Inhibitors

Cholinesterase inhibitors include donepezil (Aricept), galantamine (Reminyl), rivastigmine (Exelon), and tacrine (Cognex).

• How cholinesterase inhibitors work: Cholinesterase is an enzyme that breaks down a chemical in the brain called acetylcholine. Acetylcholine acts as an important messaging system in the brain. Brain acetylcholine levels are low in most people with Alzheimer disease. Cholinesterase inhibitors improve acetylcholine levels by inhibiting the enzyme that breaks down acetylcholine. The first cholinesterase inhibitor, tacrine, has largely been replaced by newer drugs with low risk of liver toxicity.



• Who should not use these medications: Individuals with the following conditions should not take cholinesterase inhibitors.
  
  
  • Allergy to cholinesterase inhibitors
  
  
  
  • Allergy to carbamates (rivastigmine)
  
  
  
  • Liver impairment (should not use tacrine or galantamine)
  
  
  
  • Severe kidney impairment (galantamine)
     
• Use: Administered orally (by mouth)
  
  
  • Donepezil may be taken with or without food.
  
  
  
  • Galantamine and rivastigmine should be taken with food or milk.
  
  
  
  • Tacrine should be taken on an empty stomach at least 1 hour before meals (if stomach upset occurs it may be taken with food, although with food in the stomach, less of the drug may be absorbed).
     
• Drug or food interactions: Additive effects may occur when administered with succinyl choline, other cholinesterase inhibitors, or cholinergic blockers. Quinidine or ketoconazole increase cholinesterase accumulation in the body and cause toxicity. When taken with aspirin, ibuprofen, or arthritis medicine, it may increase the risk of stomach ulcers. Avoid drugs that counteract acetylcholine’s effects, such as scopolamine (Transderm-Scop), tolterodine (Detrol), oxybutynin (Ditropan), or benztropine (Cogentin). If taking tacrine, avoid other drugs or herbal products that may increase liver toxicity, such as atorvastatin, estrogen, or acetaminophen.



• Side effects:
  
  
  • Common side effects include the following:
    
    
    • Dizziness
    
    
    
    • Nausea
    
    
    
    • Vomiting
    
    
    
    • Diarrhea
    
    
    
    • Loss of appetite
    
    
    
    • Abdominal pain
    
    
    
    • Salivation
       
  • Contact the doctor immediately if the following occur:
    
    
    • Fainting
    
    
    
    • Abnormal heart rate
    
    
    
    • Bloody or black, tarry stools
    
    
    
    • Vomiting blood or substance that looks like coffee grounds
    
    
    
    • Seizures
    
    
    
    • Severe stomach pain
       
  • Use caution if experiencing any of the following:
    
    
    • History of seizures
    
    
    
    • Asthma or chronic obstructive pulmonary disease 
    
    
    
    • Abnormal heart rhythm
    
    
    
    • Active peptic ulcer disease
    
    
    
    • Anesthesia for surgery
    
    
    
    • Liver disease (tacrine)
    
    
    
    • Parkinson disease
    
    
    
    • High or low blood pressure