In this video we will talk about this drug liver dopa plus carbidopa so in which this is this is used this is used in parkinsonism so what is parkinsonism and why it occurs parkinsonism mostly occurs in old men more than females right it is a disease of basal ganglia because of decrease dopamine in the basal ganglia region which causes moment disorder okay so
There is a moment disorder ensure in this parkinsonism patient becomes slow okay patient becomes slow there is a rigidity there are tremors in the patient and hypo or bready kinesia so patient is slow patients rigid and there are tremors and this occurs because of the disorder of the basal ganglia and there is a decreased level of dopamine so if this is our
Brain this is our ventricles okay this is our hypothalamus and there is this basic angle which is looking this is a coordinate lobe of the basic ganglia this is putamen this is globus pallidus okay and this is a thalamus and there is a midbrain okay and there is a midbrain where it is located substantia and this substantia secretes this loop so if dopamine
Is not enough in the brain this basal ganglia activity is affected and which will lead to all the symptoms of parkinsonism so what we can do is we can give them dopamine from outside like if patient is not making enough dopamine we can give them from outside through medicine now the problem with dopamine is if we give dopamine okay this is a protein right
So it will get digest in the stomach and small intestine because of the protein enzymes so we would develop the drug which was river lupa so levodopa is a pro drug and after absorption with the help of dopa decarboxylase enzyme the carboxylase enzyme this gets converted into dopamine so when we give this drug okay imagine that you have given the drug to the
Patient it has reached the small intestine sorry it has read the stomach then the small intestine then portal circulation then in the liver and then through the systemic circulation it has reached the brain okay now in the brain it will act in the basal ganglia after converting into the dopamine with the help of dopadi carboxylase now you can imagine that the
Drug is to travel through this much of fruit before reaching it so by the time it reaches the brain most of the drug will get digested okay because this dopa decarboxylase enzyme will be present in this uh at many places okay in the body in the circulation so what will happen is this dopa uh this levodopa will get converted into dopamine okay in the circulation
Because of this enzyme before reaching the brain so on one side we are getting less drug to the brain okay decrease amount of the drug to the brain and also dopamine amount of dopamine in the circulation and in the systemic body is getting increased and this can lead to arrhythmia this can lead to changes in bp so now what we can do is so this was the problem with
This drug so a scientist developed another drug that is carbidopa now this carbidopa is a drug that cannot enter the brain because it cannot cross the blood-brain barrier so when we give levodopa and carbidopa what will happen is this carbidopa will not be able to enter the brain but this livo dopa will reach the brain now what the use of carbidopa then this
Carbidopa will inhibit the enzyme dopa d carboxylase okay so this dopa decarboxylase will get inhibited if this gets inhibited then you can imagine that this levodo this levodopa which we will give with the carbidopa will prevent the conversion okay into dopamine in this systemic circulation so in the systemic circulation there will be no conversion of levodopa
Uh into dopamine okay because this carbidopa will prevent the enzyme here but as this carbidopa will not be able to enter the brain only levodopa will enter so in the brain this large amount of the liver dopa which i will reach from this systemic circulation to the brain okay will be able to convert into dopamine and it will carry out this action so this is the use
Of carbidopa with levodopa so now you understood that why we give levodopa to compensate for the dopamine right and why we give this carbidopa to prevent the peripheral conversion of now what are the side effects of this drug one is arrhythmia and other is dyskinesia after a longer term use of this drug there will be development of on and off phenomenon and
This leads to this dyskinesia okay what is on and off phenomenon on phenomenon is when the effect of the drug is on and off phenomenon is when the effect of the drug is off okay that is that means there is no effect of the drug so imagine that if you’re given the patient one dose and this is the time for the second dose okay this is first dose time and this is
Second dose time initially everything goes well okay when there is enough dopamine but with time you know that the there is a degenerative changes that occurs in the basal ganglia and also the neurons that are producing dopamine so with time there will be decrease in dopamine okay so with decrease in dopamine the dose the x amount of the dose which we are giving
To this patient will not be able to compensate for that uh decreased dopamine over time so what will happen is when you give the dose to the patient it will be normal for most of the time but by the time of the second dose okay before that for this much time the amount of the drug will be so less that it want to be able able to compensate for the dopamine
Compensate for the decreased dopamine level in the body or in the brain so during this time there will be again symptoms of parkinsonism and when you give them second dose okay then the patient will again become normal now again when the time for the another dose okay before that there will be this symptom again so this is known as on and off phenomenon it occurs
Because of the ongoing uh ongoing degenerative process in the brain okay so imagine that we are giving x amount of the drug okay and there are uh this y amount of neurons after some years this y amount of neurons will be like half of the original neurons okay so now this much amount of the drug cannot compensate for this much neurons because this much neurons
Will form very less amount of dopamine so we need to increase the dose okay but there is some limit to increasing the dose also okay so with time the treatment is like it’s not that much satisfactory but yeah this is the treatment that we have today and we are giving a patient to the patients and yeah that’s all for this video if you have any doubt you can
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Transcribed from video
Levodopa-carbidopa-Parkinsonism treatment By Neurons plus