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]
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)
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]
^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. PMID15834447.
^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.
^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. PMID9842955.
^Rang HP, Dale MM, Ritter JM, Moore PK (2003). Pharmacology (5th ed.). Edinburgh: Churchill Livingstone. ISBN978-0-443-07145-4..