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Current time:0:00Total duration:9:59

Managing Parkinson's disease with medications

Video transcript

so our friend here has recently been diagnosed with Parkinson's disease and we need to figure out what kind of medications we can give him to help manage the symptoms that he's experiencing now you might have noticed there that I said manage instead of treat and you might reasonably be thinking well wouldn't you want to treat his symptoms in other words make them completely go away and not just manage them well that would be ideal but unfortunately we don't currently have any medications that can completely get rid of the symptoms of Parkinson's disease in other words we don't currently have a way to stop or or reverse the disease progression the loss of dopamine neurons in the brain that is causing his movement symptoms so instead we have to manage his symptoms we'll have to give him some medications that will minimize how much these symptoms crop up and interfere with his daily living right so the management of Parkinson's disease may look quite different for two different people and that's because the disease affects everyone a little bit differently so we want to make sure that we figure out which movement and non movement symptoms are really affecting our patient here really interfering with his day to day tasks so that we can address them properly and not give him any medications that he doesn't need because we don't necessarily want to put everyone on every medication right away if the symptoms aren't really causing too many problems right because there can actually be short and long term side effects that we might want to minimize or delay so let's say that our patient here is really struggling with his brady kinesia his tremor and his rigidity and he's also finding himself feeling really depressed lately so we want to manage these symptoms these are the key symptoms for our guy here these are the ones that are really decreasing his quality of life so what kind of medications would help with these movement problems here well let's start off by thinking about what's going on inside of our patient that's causing these problems he's losing dopamine neurons right and when you lose dopamine neurons you end up with reduced levels of dopamine in the brain so what can we do what can we do to fix this well we can try giving him dopamine to replace the dopamine that he's lost right so that seems like a reasonable idea but there one sort of caveat there dopamine doesn't cross the blood-brain barrier that barrier that keeps unwanted molecules and substances out of our central nervous system so if we just give our guy here straight-up dopamine the blood-brain barrier won't let it cross into his brain so there won't be any increase in dopamine in his brain which is where we really need to replace it to reduce these movement symptoms so we need a way around this little conundrum here so what we can actually do is we can give him a medication that is the precursor to dopamine so in other words it will turn into dopamine in the right circumstances and lucky for us this precursor is called l-dopa so here it is here's l-dopa it can cross the blood-brain barrier so that's great we're we're in business here so we give our patient here l-dopa oh and we also know l-dopa as levodopa so you might hear here that set as well and l-dopa can cross that pesky blood-brain barrier and get converted into dopamine so therefore it increases dopamine levels in our guy's brain and just an additional little note about that it turns out that if we just give l-dopa these enzymes that we have that hang around outside of the central nervous system they actually just go ahead and convert our l-dopa into dopamine before it even has a chance to get into the brain so that's kind of a problem right that kind of defeats the purpose of giving l-dopa in the first place so what we'll do about that is we'll give him another medication called a peripheral decarboxylase inhibitor and we'll do that at the same time as we give l-dopa and now this drug the peripheral decarboxylase inhibitor it will block those enzymes from turning our l-dopa into dopamine before it gets into the brain so good now l-dopa is getting into a central nervous system and it's turning into dopamine and this is helping with his movement problems so l-dopa has generally considered our most effective medication for dealing with the movement problems and someone like our patient here with idiopathic Parkinson's disease but there are a few problems that can arise about five to ten years after someone starts taking l-dopa one thing that can happen is something called wearing off and wearing off is when a dose of l-dopa it stops lasting as long as it used to so the patience symptoms become really bothersome again before it's even time to take the next dose of l-dopa so what can we do about this this wearing off well where does that dopamine go it's degraded right it's being broken down by special enzymes that we have in our brain so we can try to slow down that degradation of dopamine that's what we can do thatwe can hang around a bit longer and keep stimulating our dopamine receptors and that can help get our patient here through to their next dose of l-dopa without their symptoms coming back to bother them so we can do this with a few different types of medications we can use something called a monoamine oxidase B inhibitor also known as an MAO B inhibitor so Mao B is an enzyme that hangs around in our brain and it breaks down dopamine so we don't want that so we can use an MAO B inhibitor to stop this breakdown and that allows us to keep higher levels of dopamine in the brain good so that's so that's one thing that we can do to prevent this wearing off and another type of medication we can use is called a catechol o methyl transferase inhibitor man that's a mouthful but if we break that down the name actually makes sense so catechol here stands for catecholamine and dopamine is a type of molecule in the catecholamine group so is epinephrine and and norepinephrine you might have heard of those as well so these are all catecholamines and methyl transferase here means that this is an enzyme remember that the ACE part means that it's an enzyme this enzyme what it does is it transfers a methyl group onto the dopamine and this in activates the dopamine so already we know that we're gonna have to do something about this because we want our dopamine to stick around for a bit longer so when we give our patient here a calm T inhibitor I'll just go ahead and shorten this to calm t we stop that breakdown right so we have more dopamine floating around to bind to the receptors the dopamine receptors and reduce movement symptoms so another problem that we can see with prolonged use of l-dopa is too much involuntary movement now that's a little unexpected right that's kind of the opposite of what we would expect in someone with Parkinson's disease I mean Parkinson's disease messes around with our basal ganglia pathways so that we end up with a reduction in movement right so why are we getting too much movement here well we can think of l-dopa is a pendulum a pendulum that's trying to swing our patient from reduced movements to being able to move normally but over time after being on l-dopa for several years the pendulum can kind of overshoot and we end up with too much movement and we call this dyskinesia so that presents an interesting little problem here essentially what we need to think about when we're treating parkinson's disease is that well l-dopa is our most effective medication but if we use it for a long time there's a chance that the pendulum will swing the other way so to speak and dyskinetic movements will result so what do we do well sometimes we might delay starting l-dopa for as long as we reasonably can so in other words we'll try to manage our patient symptoms without resorting to l-dopa right away or maybe we'll just try to use a little bit of l-dopa and use another medication as well at least until later on in the disease when we really really need l-dopa l-dopa has kind of like the ace up our sleeve that we want to hang on to until we want to play it and that way we could maybe delay these long term side effects from happening so then the question becomes other than dopamine what else could we give our patient here that would help him with his movement problems well we could give him something that acts like dopamine right something that stimulates his dopamine receptors the same way that dopamine does so let's do that and and these are called dopamine agonists they play the role of dopamine kind of like how a substitute teacher plays the role of the regular teacher and helps teach the class while the regular teacher is away so when we give him these dopamine agonists the neurons with dopamine receptors are stimulated just as though dopamine was there doing the job so you might be wondering okay well if these dopamine agonists act like dopamine then why is l-dopa the most effective medication shouldn't these agonists be just as effective well while these agonists do acts like dopamine they're not dopamine right they're not a perfect fit for the receptor just like how the substitute teacher just isn't as good a fit for the class as the regular teacher is so these agonists they just aren't as effective as the real thing but they can be really helpful maybe early on when symptoms aren't too bad when the disease hasn't progressed too far or maybe when we're using them together with l-dopa so that may be l-dopa can be used a little bit less so those are the main types of medications that we would normally use to manage the movement symptoms of Parkinson's disease but we also need to manage the other symptoms right like the depression that our patient is experiencing so one thing that we we might want to do before we try to treat his depression or any other symptom that someone with Parkinson's disease might experience is that we would want to figure out if the symptom is due to the disease itself or if it's a side effect of one of his other medications if it is the disease itself and the symptom needs medication then we would just try to find the most suitable medication that we can for managing it and if instead it's a side effect of a medication that he's already on then we would try if we could to maybe adjust the dose of that medication if possible so that he experiences minimal side effects