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Tacrine
Clinical data
Trade names	Cognex
AHFS/Drugs.com	Monograph
MedlinePlus	a693039
Pregnancy; category	AU: C; ;
Routes of; administration	Oral, rectal
ATC code	N06DA01 (WHO) ;
Legal status
Legal status	AU: S4 (Prescription only); BR: Class C1 (Other controlled substances); UK: POM (Prescription only); US: ℞-only;
Pharmacokinetic data
Bioavailability	2.4–36% (oral)
Protein binding	55%
Metabolism	Hepatic (CYP1A2)
Elimination half-life	2–4 hours
Excretion	Renal
Identifiers
	IUPAC name 1,2,3,4-Tetrahydroacridin-9-amine;
CAS Number	321-64-2 ;
IUPHAR/BPS	6687;
DrugBank	DB00382 ;
ChemSpider	1859 ;
UNII	4VX7YNB537;
ChEBI	CHEBI:45980 ;
ChEMBL	ChEMBL95 ;
PDB ligand	THA (PDBe, RCSB PDB);
CompTox Dashboard (EPA)	DTXSID1037272 ;
ECHA InfoCard	100.005.721
Chemical and physical data
Formula	C13H14N2
Molar mass	198.269 g·mol−1
3D model (JSmol)	Interactive image;
Melting point	183 °C (361 °F)
Boiling point	358 °C (676 °F)
	SMILES n1c3c(c(c2c1cccc2)N)CCCC3;
	InChI InChI=1S/C13H14N2/c14-13-9-5-1-3-7-11(9)15-12-8-4-2-6-10(12)13/h1,3,5,7H,2,4,6,8H2,(H2,14,15) ; Key:YLJREFDVOIBQDA-UHFFFAOYSA-N ;
	(verify)

Tacrine is a centrally acting acetylcholinesterase inhibitor 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 in 1949. It also acts as a histamine N-methyltransferase inhibitor.^[2]

Clinical use

Tacrine was the prototypical cholinesterase inhibitor for the treatment of Alzheimer's disease. William K. Summers received a patent for this use in 1989.^[3]^[4]^[5] 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.^[6]^[7]

Tacrine has been discontinued in the US^[8] in 2013, due to concerns over safety.^[9]

Tacrine was also described as an analeptic agent used to promote mental alertness.^[10]

Adverse effects

Very common (>10% incidence) adverse effects include^[8]

Increased liver function tests (LFT), with 49% of patients displaying elevated ALA^[11]
Diarrhea
Dizziness
Headache
Nausea
Vomiting

Common (1-10% incidence) adverse effects include^[8]^[12]

Abdominal pain
Agitation
Anxiety
Ataxia — decreased control over bodily movements.
Belching
Confusion
Conjunctivitis (a link to tacrine treatment has not been conclusively proven)
Constipation
Diaphoresis — sweating.
Fatigue
Hallucinations
Indigestion
Insomnia
Myalgia — muscle pain
Rash
Rhinitis
Somnolence
Tremor
Urinary incontinence
Weight loss

Uncommon/rare (<1% incidence) adverse effects include^[12]

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.
Hepatotoxicity (that is toxic effects on the liver)
Ototoxicity (hearing/ear damage; a link to tacrine treatment has not been conclusively proven)
Seizures
Taste changes

Unknown incidence adverse effects include^[12]

Bradycardia
Delirium
Depression
Hypotension
Suicidal ideation and behaviour
Urinary tract infection
Other optic effects such as glaucoma, cataracts, etc. (also not conclusively linked to tacrine treatment)

Overdose

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.^[12]

Pharmacokinetics

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.^[12]

References

^ Anvisa (2023-03-31). "RDC Nº 784 - Listas de Substâncias Entorpecentes, Psicotrópicas, Precursoras e Outras sob Controle Especial" [Collegiate Board Resolution No. 784 - Lists of Narcotic, Psychotropic, Precursor, and Other Substances under Special Control] (in Brazilian Portuguese). Diário Oficial da União (published 2023-04-04). Archived from the original on 2023-08-03. Retrieved 2023-08-16.
^ 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. doi:10.1358/mf.2005.27.3.890872. PMID 15834447.
^ US 4816456, Summers WK, "Administration of monoamine acridines in cholinergic neuronal deficit states", issued 28 March 1989
^ Waldholz M (4 August 1987). 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-for research Furor. Wall Street Journal (Report). p. A-1.
^ Peacock D (25 March 2005). "New Mexico Doctor invents drugs, supplements for Alzheimer's disease, Multiple Sclerosis". NM Bus Weekly.
^ Qizilbash N, Whitehead A, Higgins J, Wilcock G, Schneider L, Farlow M (November 1998). "Cholinesterase inhibition for Alzheimer disease: a meta-analysis of the tacrine trials. Dementia Trialists' Collaboration". JAMA. 280 (20): 1777–1782. doi:10.1001/jama.280.20.1777. PMID 9842955.
^ Rang HP, Dale MM, Ritter JM, Moore PK (2003). Pharmacology (5th ed.). Edinburgh: Churchill Livingstone. ISBN 978-0-443-07145-4..
^ ^a ^b ^c "tacrine (Discontinued) - Cognex". Medscape Reference. WebMD. Archived from the original on 30 June 2019. Retrieved 8 October 2013.
^ "Tacrine". LiverTox. U.S. National Institutes of Health. Archived from the original on 2019-07-02.
^ Elks J, Ganellin CR, eds. (1990). Dictionary of Drugs. doi:10.1007/978-1-4757-2085-3. ISBN 978-1-4757-2087-7.
^ Watkins PB, Zimmerman HJ, Knapp MJ, Gracon SI, Lewis KW (April 1994). "Hepatotoxic effects of tacrine administration in patients with Alzheimer's disease". JAMA. 271 (13): 992–998. doi:10.1001/jama.1994.03510370044030. PMID 8139084.
^ ^a ^b ^c ^d ^e Truven Health Analytics, Inc. DRUGDEX® System (Internet) [cited 2013 Oct 8]. Greenwood Village, CO: Thomsen Healthcare; 2013.