Which class of neuromuscular blockers has a mechanism based on depolarization?

The class of neuromuscular blockers that operates through a mechanism based on depolarization is indeed the depolarizing agents, also referred to as agonists. These agents work by binding to the nicotinic acetylcholine receptors at the neuromuscular junction, mimicking the action of acetylcholine. Upon binding, they cause persistent depolarization of the motor end plate, which leads to repeated stimulation of the muscle fiber. This initial muscle contraction (fasciculation) is followed by a phase of paralysis as the receptors become desensitized and unable to respond to further stimulation.

In contrast, nondepolarizing neuromuscular blockers act as antagonists, competing with acetylcholine for binding at the neuromuscular junction but do not cause depolarization. They effectively prevent any action of acetylcholine without inducing the initial muscle contraction.

Selective blockers and related classifications may include additional features or mechanisms, but fundamentally, they do not align with the depolarization mechanism characteristic of the agonist (depolarizing) class. Hence, the ability of depolarizing neuromuscular blockers to produce an initial depolarization followed by paralysis is the key aspect that distinguishes them within this pharmacological context.