Final answer:
Benzocaine is a local anesthetic with a quick onset of action, usually taking effect within minutes. It and other local anesthetics like lidocaine work by blocking sodium channels, preventing nerve impulse transmission, and causing reversible sensory and motor paralysis.
Step-by-step explanation:
Benzocaine is a local anesthetic known for its short-acting effect and rapid onset of action. The onset of action refers to the period from the administration of the medication until the start of its therapeutic effect. For benzocaine, the onset is typically just a few minutes, though precise timing can vary based on the formulation and individual differences.
Local anesthetics like benzocaine work by blocking sodium channels in neuronal membranes. This action prevents the initiation and transmission of nerve impulses, leading to a reversible loss of sensation in the area where the anesthetic is applied. The effect is that sensory and sometimes motor paralysis occurs in the region supplied by the nerves, without causing structural damage or long-term effects on nerve fibers or cells.
Different types of anesthetics perform differently. The first known local anesthetic was cocaine, derived from the leaves of Erythroxylon coca. Today, safer alternatives like benzocaine and lidocaine are commonly used instead. Lidocaine, similar to benzocaine, acts as a Na+ channel blocker, making it an effective local anesthetic for inducing numbness and managing pain in specific areas of the body.