Nicotinic agonist

A nicotinic agonist is a drug that mimics the action of acetylcholine (ACh) at nicotinic acetylcholine receptors (nAChRs). The nAChR is named for its affinity for nicotine.

Examples include nicotine (by definition), acetylcholine (the endogenous agonist of nAChRs), choline, epibatidine, lobeline, varenicline and cytisine.

Nicotine has been known for centuries for its intoxicating effect. It was first isolated in 1828 from the tobacco plant by German chemists, Posselt and Reimann.

The discovery of positive effects from nicotine on animal memory was discovered by in vivo researches in the mid 1980s. Those researches led to a new era in studies of nicotinic acetylcholine receptor (nAChR) and their stimulation but until then the focus had mainly been on nicotine addiction. The development of nAChR agonists began in the early 1990s after the discovery of nicotine’s positive effects. Some research showed a possible therapy option in preclinical researches. ABT-418 was one of the first in a series of nAChR agonists and it was designed by Abbott Labs. ABT-418 showed significant increase of delayed matching-to-sample (DMTS) performance in matured macaque apes of different species and sex. ABT-418 has also been examined as a possible treatment to Alzheimer’s disease, Parkinson’s disease and attention-deficit hyperactivity disorder: those experiments showed positive outcomes.

One of the first nAChR active compounds, besides nicotine, that was marketed as a drug was galantamine, a plant alkaloid that works as a weak cholinesterase inhibitor (IC50=5µM) as well as an allosteric sensitizer for nAChRs (EC50=50 nM).

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