Systematic (IUPAC) name
Clinical data
Trade names Cognex
  • AU: C
  • US: C (Risk not ruled out)
Legal status
Routes of
Oral, rectal
Pharmacokinetic data
Bioavailability 2.4–36% (oral)
Protein binding 55%
Metabolism Hepatic (CYP1A2)
Biological half-life 2–4 hours
Excretion Renal
CAS Registry Number  Y
ATC code N06
DrugBank  Y
ChemSpider  Y
PDB ligand ID THA (, )
Chemical data
Formula C13H14N2
Molecular mass 198.264 g/mol
Physical data
Melting point 183 °C (361 °F)
Boiling point 358 °C (676 °F)

Tacrine is a centrally acting anticholinesterase and indirect cholinergic agonist (parasympathomimetic). It was the first centrally acting cholinesterase inhibitor approved for the treatment of Alzheimer's disease, and was marketed under the trade name Cognex. Tacrine was first synthesised by Adrien Albert at the University of Sydney. It also acts as a histamine N-methyltransferase inhibitor.[1]


  • Clinical use 1
  • Adverse Effects 2
    • Overdose 2.1
  • Pharmacokinetics 3
  • References 4
  • External links 5

Clinical use

Tacrine was the prototypical cholinesterase inhibitor for the treatment of Alzheimer's disease. William K. Summers received a patent for this use (US Patent No. 4,816,456).[2][3][4] Studies found that it may have a small beneficial effect on cognition and other clinical measures, though study data was limited and the clinical relevance of these findings was unclear.[5][6]

Tacrine has been discontinued in the US[7] in 2013, due to concerns over safety.[8]

Adverse Effects

Very Common (>10% incidence) adverse effects include[7]
  • Increased LFTs
  • Nausea
  • Vomiting
  • Diarrhea
  • Headache
  • Dizziness
Common (1-10% incidence) adverse effects include[7][9]
  • Indigestion
  • Belching
  • Abdominal pain
  • Myalgia — muscle pain
  • Confusion
  • Ataxia — decreased control over bodily movements.
  • Insomnia
  • Rhinitis
  • Rash
  • Fatigue
  • Weight loss
  • Constipation
  • Somnolence
  • Tremor
  • Anxiety
  • Urinary incontinence
  • Hallucinatons
  • Agitation
  • Conjunctivitis (a link to tacrine treatment has not been conclusively proven)
  • Diaphoresis — sweating.
Uncommon/Rare (<1% incidence) adverse effects include[9]
  • Hepatotoxicity (that is toxic effects on the liver)
  • Ototoxicity (hearing/ear damage; a link to tacrine treatment has not been conclusively proven)
  • Seizures
  • Agranulocytosis (a link between treatment and this adverse effect has not been proven) — a potentially fatal drop in white blood cells, the body's immune/defensive cells.
  • Taste changes
Unknown incidence adverse effects include[9]
  • Urinary tract infection
  • Delirium
  • Other optic effects such as glaucoma, cataracts, etc. (also not conclusively linked to tacrine treatment)
  • Depression
  • Suicidal ideation and behaviour
  • Hypotension
  • Bradycardia


As stated above, overdosage of tacrine may give rise to severe side effects such as nausea, vomiting, salivation, sweating, bradycardia, hypotension, collapse, and convulsions. Atropine is a popular treatment for overdose.[9]


Major form of metabolism is in the liver via hydroxylation of benzylic carbon by CYP1A2. This forms the major metabolite 1-hydroxy-tacrine (velnacrine) which is still active.[9]


  1. ^ Taraschenko, OD; Barnes, WG; Herrick-Davis, K; Yokoyama, Y; Boyd, DL; Hough, LB (April 2005). "Actions of tacrine and galanthamine on histamine-N-methyltransferase.". Methods and findings in experimental and clinical pharmacology 27 (3): 161–165.  
  2. ^ {US Patent No. 4,816,456} http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=4,816,456.PN.&OS=PN/4,816,456&RS=PN/4,816,456
  3. ^ Waldholz M. A Psychiatrist’s work leads to a US study of Alzheimer’s drug: but Dr. Summers shuns test, seeks to widen his own; is Memory really aided; Fee-forresearch Furor. Wall Street Journal. Tuesday August 4, 1987 p A-1
  4. ^ Peacock D. New Mexico Doctor invents drugs, supplements for Alzheimer’s disease, Multiple Sclerosis. NM Bus Weekly. 25 MAR 2005
  5. ^ Qizilbash N, Whitehead A, Higgins J, et al. (1998). "Cholinesterase inhibition for Alzheimer disease: a meta-analysis of the tacrine trials". Journal of the American Medical Association 280 (20): 1777–82.  
  6. ^ Rang HP, Dale MM, Ritter JM, Moore PK (2003). Pharmacology (5th ed.). Edinburgh: Churchill Livingstone.  .
  7. ^ a b c "tacrine (Discontinued) - Cognex". Medscape Reference. WebMD. Retrieved 8 October 2013. 
  8. ^ Tacrine at LiverTox
  9. ^ a b c d e Truven Health Analytics, Inc. DRUGDEX® System (Internet) [cited 2013 Oct 8]. Greenwood Village, CO: Thomsen Healthcare; 2013.

External links

  • Acetylcholinesterase: A gorge-ous enzyme QUite Interesting PDB Structure article at PDBe