Overview – Skeletal Muscle Relaxants

00:01 Welcome to pharmacology by Lecturio. I'm Dr. Pravin Shukle. We're going to be talking about skeletal muscle relaxants today.

00:10 With respect to skeletal muscle relaxants, we have several categories of drugs.

00:15 We have those drugs that are the neuromuscular blockers. They can be either depolarizing like succinylcholine, or non-depolarizing like this list of agents. We can also have spasmolytic agents.

00:27 Spasmolytic agents are used in certain types of diseases that are not necessarily related to that which we use for anesthesia. We can use spasmolytics in acute use like cyclobenzaprine and chronic use in chronic spasmotic diseases such as those drugs like baclofen and others.

00:49 Let's take a look at how skeletal muscle contracts. Here we have two examples of ion channel.

00:55 One is closed in its resting state. When you have an agonist, whatever that agonist may be, let's say it's cyclic AMP or calcium, that agonist will open up the channel and allow ions to flow in.

01:10 Those ions stimulate a cascade of reactions that ultimately result in contraction of the muscle.

01:17 Acetylcholine is a common stimulus for opening that channel.

01:23 If you have a nondepolarizing blocker, that agent will come along and lock the gate closed.

01:30 A depolarizing blocker on the other hand will lock the gate open.

01:36 So, the gate that is open is still allowing ions to flow through But it leaves it open, leaving the muscle completely depolarized.