Pharmacodynamics Pain is caused by the stimulation of free nerve endings. When the nerve endings are stimulated, sodium enters the neuron, causing depolarization of the nerve and subsequent initiation of an action potential. The action potential is propagated down the nerve toward the central nervous system, which interprets this as pain.<unk>  acts to inhibit the voltage-dependent sodium channels (VDSCs) on the neuron membrane, stopping the propagation of the action potential.
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