Compound/
Metabolited
MH+a RRTb Fragment Ions
from CIDc (m/z)
Proposed transformation from donepezil
donepezil 380 1.00 362, 288, 273, 243, 205, 189 151, 91 NA
M1/M2 366 0.96 348, 274, 259, 229,175, 137 91 O-demethylation
M4 290 0.89 290, 273, 261, 255, 243, 229, 205, 189, 151, 82 N-dealkylation
M6 396 1.02 378, 288, 273,243, 189, 151, 91 N-oxidation
M11/12 542 0.90 542, 366 O-demethylation/glucuronidation
M3 396 0.95 378, 290, 286,  241, 204, 107, 91 phenyl hydroxylation
aMH+: Protonated molecular ion from electrospray ionization.
bRRT: Relative retention time based upon LC method.
cCID: Collision induced dissociation
dNomenclature was taken from Matsui et al. (Matsui K, Mishima M, Nagai Y,
Yuzariha T, and Yoshimura T (1999) Drug Metab Dispos 27: 1406-1414)

Table 1: LC-MS/MS Characteristics of Donepezil and its Major Metabolites.