F. Bosch et al., COMPARATIVE EFFECTS OF VELNACRINE, TACRINE AND PHYSOSTIGMINE ON THE TWITCH RESPONSES IN THE RAT PHRENIC-HEMIDIAPHRAGM PREPARATION, General pharmacology, 24(5), 1993, pp. 1101-1105
1. Cholinesterase inhibitors potentiated twitch responses induced by n
erve stimulation, with physostigmine more potent than tacrine and veln
acrine. However, at higher concentrations, tacrine decreased twitch re
sponses in a concentration-dependent manner. 2. Tacrine strongly depre
ssed directly-induced twitch responses, whereas the other drugs had mi
nimal effects. 3. Physostigmine was the most potent drug in reversal o
f tubocurarine-induced blockade, but its antagonism index was similar
to those obtained with tacrine and velnacrine at higher concentrations
. When evaluating their ability to reverse neomycin-induced blockade,
all drugs exhibited a similar effect. 4. It is concluded that tacrine
and velnacrine are less potent than physostigmine in potentiating skel
etal neuromuscular transmission. Additionally, the blocking effects of
tacrine could limit its therapeutic efficacy.