Cholinergics

Two different mechanisms under one heading, both pointed at raising cholinergic tone. The precursors — choline bitartrate, alpha-GPC and citicoline — supply substrate for acetylcholine synthesis and differ mainly in how much of a dose reaches the brain as choline. The inhibitors — huperzine A and donepezil — leave synthesis alone and block the enzyme that clears acetylcholine from the synapse, so the effect keeps building while the drug is present. Reading one half's tolerability onto the other is the mistake this family exists to prevent.

Cholinesterase inhibition is where the harm is: too much produces a recognisable cholinergic picture — nausea, sweating, salivation, cramps, a slowed heart — and it is additive with any other inhibitor. Donepezil is a prescription drug and huperzine A is sold as a supplement, which says nothing about their relative potency. Antimuscarinics, including the deliriants, oppose them directly.