Welcome to pharmacology by Lecturio. I'm Dr. Pravin Shukle.
We're going to be talking about skeletal muscle relaxants today.
With respect to skeletal muscle relaxants,
we have several categories of drugs.
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.
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.
Let's take a look at how skeletal muscle contracts.
Here we have two examples of ion channel.
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.
Those ions stimulate a cascade of reactions
that ultimately result in contraction of the muscle.
Acetylcholine is a common stimulus for opening that channel.
If you have a nondepolarizing blocker,
that agent will come along and lock the gate closed.
A depolarizing blocker on the other hand
will lock the gate open.
So, the gate that is open is still
allowing ions to flow through
But it leaves it open,
leaving the muscle completely depolarized.