Hi. Welcome to our video on Parkinson's medication.
Now this is part of a series and we're gonna talk about levodopa and its good friend carbidopa.
Now let's do a quick review.
If you watched our overview series then you've seen some of these before
but a review is always a good idea.
Repetition for your brain is a way to encode and recall information more effectively.
So, Parkinson's Disease is a progressive nervous system disorder.
It affects a person’s ability to control movement.
It also negatively impacts how they feel, how they think, how they sleep and how they talk.
So you’ve got common symptoms like tremors and bradykinesia which means slow movement,
they have stiff muscles, kind of stooped over, you can see that in the picture there.
They have changes to their speech and they lose their fine motor control
so they can't button a shirt very easily and it’s difficult for them to use hand writing or to sign a check.
Parkinson interferes with the person’s ability to work, to dress themselves, to feed themselves,
and just your basic daily activities.
So they’ve got these dyskinesias, the difficulty with movement and tremors, the rigidity,
the posture instability so they're at risk for falling and they have this slowed movement.
So if I was gonna zero in and think about a great summary slide for difficult movement,
I would think tremors, slow movement, risk for falls, and they're very, very, stiff.
Now it’s not enough that they have these motor symptoms to deal with,
Parkinson’s patients can also deal with autonomic disturbances and there is a significantly long list for you there.
Also depression, psychosis, dementia and they can have this flat affect
where it appears like they have no emotion, they don’t have much of a facial expression.
Okay, so Parkinson’s disease is imbalanced, let me say that again -
Parkinson's disease is imbalance.
Okay, I want you to you think about imbalance in movement,
an imbalance between dopamine and acetylcholine in the brain.
So I'm talking to you this way because I want to make the point,
Parkinson’s is all about imbalance - in their movements
and in their neurotransmitters in the brain - dopamine and acetylcholine.
They don’t have enough dopamine; that’s why you've got a scale therefore to help your memory,
see that the dopamine in relationship to the acetylcholine there's just not enough of it
to keep a proper balance in the brain.
So why don’t we just give Parkinson’s patients dopamine?
See if you can recall the answer to this question. It seems logical that if all their problems are
because they don’t have enough dopamine in their brain, just give them dopamine,
don’t we have dopamine?
Yeah, we do but it can't cross the blood-brain barrier that’s why if we gave them dopamine,
let's say if we gave it IV, it has sympathetic nervous system response
but it won't make it across the blood-brain barrier because of that tight junction.
On the left you see the normal blood vessel that has those portals where things can cross
but in the brain, it really tries to protect itself so it has a blood-brain barrier, super tight junctions,
they don’t have the same kind of pores so they need some type of active transport to make it across.
So we give drugs that help increase dopamine levels in the brain or act like dopamine in the brain.
Okay, now when it comes to our options for treating Parkinson’s,
what about six different types or mechanisms of action?
Remember we’re trying to address the imbalance between dopamine and acetylcholine.
Now the first group are the MAO-B inhibitors, they conserve dopamine in the brain.
If the patient has mild symptoms of Parkinson’s we would likely start with this group of medications.
Now the next is the NMDA-type glutamate antagonist
and when we have this type of antagonist or blocker it will increase the amount of dopamine released.
Third group are dopamine agonist, they mimic or act like dopamine in the brain.
Dopamine prodrugs help replace missing dopamine.
We’ll also talk about carbidopa and the decarboxylase inhibitor that we use with levodopa.
Now a COMT inhibitor optimizes the delivery of levodopa to the brain, that’s a good thing
because the more levodopa the more dopamine we’ll end up with and the sixth group is an anticholinergic.
Now the first five groups help us have more dopamine in the brain.
The sixth group the anticholinergic block the cholinergic receptors or the acetylcholine receptors
so that helps us kind of even out the odds.
We have way too much acetylcholine compared to the amount of dopamine
that is available so the first five ways increase the amount of dopamine that is available or act like they're dopamine,
and the sixth one blocks the action of acetylcholine