Anticholinergic Drugs To Avoid

Anticholinergic drugs can be toxic to the central nervous system over the long term. Blockade of nicotinic and muscarinic receptors impinges on working memory and long-term memory.

Harvard developed a scale (from 1 to 3) that ranks drugs according to their anticholinergic burden. A good proxy for anticholinergic burden is to look at the binding affinity of a drug for muscarinic receptors (e.g., M1, M2). Tighter binding to muscarinic (and nicotinic) receptors is reflected by a smaller Kd (dissociation constant).

Some common examples of OTC and prescription drugs include:

  • diphenhydramine (Benedryl)
  • trihexyphenidyl (Artane)
  • benztropine mesylate (Cogentin)
  • biperiden (Akineton)
  • clomipramine (Anafranil)
  • chlorpromazine (Thorazine)

Further reading: Drugs That Impair Memory.