The skeletal muscle relaxant, vecuronium, acts at cholinergic receptors where it exhibits:
Vecuronium is a curare-like drug classified as a nondepolarizing skeletal muscle relaxant. It exhibits pharmacologic antagonism by competing with acetylcholine for available N2-nicotinic receptors on the motor end plate. In this reversible mechanism, vecuronium exhibits affinity, or the ability to bind with a paicular receptor. Vecuronium does not elicit a response in the muscle cell it lacks efficacy, or effectiveness, the ability to produce an effect relative to a given number of drug-receptor complexes. Vecuronium prevents depolarization, thereby preventing the muscle cell from contracting. It has no effect on the regulation of receptor numbers at synapses. Ref: Hibbs R.E., Zambon A.C. (2011). Chapter 11. Agents Acting at the Neuromuscular Junction and Autonomic Ganglia. In L.L. Brunton, B.A. Chabner, B.C. Knollmann (Eds), Goodman & Gilman's The Pharmacological Basis of Therapeutics, 12e.
Affinity but no efficacy
Efficacy but no affinity
Receptor upregulation
Affinity and efficacy