Acetylcholinesterase (AChE) inhibitors from several chem. classes have been tested for the symptomatic treatment of Alzheimer's disease; however, the therapeutic success of these compounds has been limited.Recently, another AChE inhibitor, galanthamine hydrobromide (GAL), has shown increased clin. efficacy and safety.Using biochem., behavioral and pharmacokinetic analyses, this report compares GAL with two of its analogs, 6-O-acetyl-6-O-demethylgalanthamine hydrochloride (P11012) and 6-O-demethyl-6-O[(adamantan-1-yl)-carbonyl]galanthamine hydrochloride (P11149), for their therapeutic potential.P11012 and P11149 were found to be potent, competitive and selective inhibitors of AChE, demonstrating central cholinergic activity, behavioral efficacy and safety.P11012 and P11149, through pharmacokinetic analyses, were shown to act as pro-drugs, yielding significant levels of 6-O-demethylgalanthamine.In vitro, 6-O-demethylgalanthamine was 10- and 20-fold more potent than GAL as an inhibitor of AChE, and it demonstrated greater selectivity for inhibition of AChE vs. butyrylcholinesterase.Like GAL, both P11012 and P11149 showed central cholinergic activity biochem., by significantly inhibiting rat brain AChE; physiol., by causing hypothermia; and behaviorally, by attenuating scopolamine-induced deficits in passive avoidance.In addition, GAL, P11012 and P11149 enhanced step-down passive avoidance, another measure of behavioral efficacy.By comparing efficacious doses with primary overt effects, P11012 and P11149 had better oral therapeutic indexes than GAL.Oral pharmacokinetic analyses of GAL, P11012 and P11149 revealed differences.Although P11012 and P11149 exhibited similar area under the curve values, P11149 had slower, lower and more sustained concentration maximum levels.P11012 and GAL rapidly reached their concentration maximum, but GAL, in brain, had the highest area under the curve and concentration maximumBecause of its composite profile, including duration of action, oral therapeutic index and pharmacokinetics, P11149 is considered the better therapeutic candidate for the treatment of Alzheimer's disease.