1,2,3,4-TETRAHYDRO-9-ACRIDINAMINE

In the 1950s, tacrine was used experimentally to reverse cholinergic coma in animals. In the 1960s, tacrine was used to reverse the effects of phencyclidine-like drugs. It was also marketed for many years as a respiratory stimulant. In 1993, the US Food and Drug Administration approved tacrine for the treatment of symptoms of mild to moderate Alzheimer’s disease.

The current use of tacrine is limited due to its poor oral bioavailability, the necessity for four daily doses, and serious side effects (including nausea, vomiting, dry mouth, indigestion, diarrhea, loss of appetite, urinary incontinence, collapse, convulsions, and hepatotoxicity). Currently, newer cholinesterase inhibitors (such as donepezil, rivastigmine, and galantamine) are preferred over tacrine.

ChEBI: Tacrine is a member of the class of acridines that is 1,2,3,4-tetrahydroacridine substituted by an amino group at position 9. It is used in the treatment of Alzheimer's disease. It has a role as an EC 3.1.1.7 (acetylcholinesterase) inhibitor. It is a member of acridines and an aromatic amine. It is a conjugate base of a tacrine(1+).

Tetrahedron Letters, 4, p. 1277, 1963 DOI: 10.1039/jr9630005127

Tacrine has numerous mechanisms of action. The putative principal mechanism of action of tacrine for Alzheimer’s disease is reversible inhibition of acetylcholinesterase (AChE), which thereby slows the breakdown of the chemical messenger acetylcholine (ACh) in the brain. Tacrine also inhibits butyrylcholinesterase activity. In addition, tacrine blocks sodium and potassium channels. Tacrine also acts as a histamine N-methyltransferase inhibitor.
At a therapeutic dose, tacrine causes liver toxicity. Cytotoxicity studies using the human liver cell line HepG2 showed that a therapeutic blood concentration of tacrine induces reactive oxygen species production and glutathione depletion, suggesting that oxidative stress might be involved in tacrine hepatotoxicity.