Test 1 Flashcards
What does the central nervous system act upon?
the brain and the spinal cord
Is the central nervous system and open or a closed system?
closed
There are a bunch of neurotransmitters in the central nervous system at least _______ have been identified and there are a lot more that are suspected.
21
There are a lot more keys floating around in our head then there are in the periphery.
____________, there are a bunch of them, their precise function is not clear, it is difficult to know exactly how central nervous system drugs work.
Neurotransmitters
Passage through the blood brain barrier is limited to what?
lipid soluble agents,
drugs that are able to cross via active transport system
also any highly protein-bound drugs generally cannot cross.
What are the characteristics that a drug needs to have in order to pass freely through the body?
Nonionized, non polar, lipophylic, and minimal protein-bound are the characteristics that allow drugs to pass freely through the body.
Drugs that are not able to be _______ _______ are difficult to get into the brain because of the blood brain barrier.
actively transported
Why is the blood brain barrier a mixed blessing?
it protects our brain, but when the brain is diseased it makes it extremely difficult to get medication into the brain.
What is dopamine?
Dopamine is Catecholamine. This prevents it from crossing the blood brain barrier.
In Parkinson’s disease, the problem is that the brain does not have enough ___________.
dopamine, but the dopamine is hard to get into the brain because it’s a Catecholamine.
Describe Central Nervous System Adaptation
When the central nervous system is exposed to drugs on a chronic basis, adaptive changes occur over time.
In essence you may see effects later as opposed to earlier. So oftentimes you need to be patient when you’re talking about central nervous system type drugs.
For example if a person is depressed, and they are put on an antidepressant and they start feeling good in about a week, that is called the placebo effect because the medication has not had enough time to cause adaptation in the brain.
The same thing applies for schizophrenia medications, anxiety medications, seizure medication and Parkinson’s disease medications.
What are some characteristics that you see with central nervous system adaptation?
Some of the things that you can see with central nervous system adaptation are increased therapeutic effects, decreased side effects, tolerance and physical dependence.
Are increased therapeutic effects seen earlier or later when taking a central nervous system medication?
Increased therapeutic effects are often seen later when taking the medication such as the person’s depression gets better the person seizures are better controlled the person has less anxiety etc. as well as we will see less side effects.
An example of this would be a person that takes morphine for the first time or any opioid will have nausea and vomiting, but the more that they take it and are exposed to it the nausea and vomiting will subside.
What is tolerance?
Tolerance, is a reduced responsiveness with prolonged exposure.
For example a person that has chronic pain such as cancer pain, their pain medication will stop working with prolonged exposure so it is absolutely appropriate for the doctor to crank up the dose to help them not be in pain.
What is physical dependance?
Physical dependence, a state where abrupt discontinuation results in withdraw.
The brain, due to the adaptive changes, needs the medication to function properly and cannot be stopped abruptly.
Physical dependence does not always mean that the patient is abusing the medication. It just means that the brain has adapted to the medication, and the medication needs to be weaned off.
What is Parkinson’s Disease?
Parkinson’s disease is a neurologic disease. Parkinson’s disease- disease of extrapyramidal system characterized by dyskinesias (tremors, rigidity, postural instability and bradykinesia).
What causes Parkinson’s disease?
Results from an imbalance of dopamine (inhibitory) and acetylcholine (excitatory) in the striatum.
How do people with parkinson’s disease present?
Parkinson’s disease presents with a masked face, sometimes drooling, shuffling gait, stooped over, cogwheeling, off balanced and they can fall easy.
What is the goal of therapy for Parkinson’s disease?
The goal of therapy is to improve the patient’s ability to carry out activities of daily living.
There is no cure for Parkinson’s disease.
What is the main neurotransmitter in the peripheral nervous system?
Acetylcholine
About how many people does parkinson’s effect?
Parkinson’s disease affects over 1 million Americans, it is second to Alzheimer’s disease. It is the most common degenerative disease of neurons.
How can you establish balance in a Parkinson’s patients brain?
In Parkinson’s disease, since you don’t have enough dopamine you need to reestablish balance between dopamine and acetylcholine.
You can do this by adding more dopamine, or by taking away some of the acetylcholine.
What is the pharmacotherapy goal for Parkinson’s?
Pharmacotherapy goal is to restore balance between acetylcholine and dopamine in the brain.
What is Wearing-Off?
Wearing off, this is almost like a light switch. It happens at the end of the dosing interval, And indicates sub therapeutic levels of dopamine in the brain.
When this happens symptoms begin to reemerge.
What could you do to prevent the wearing off of a drug?
One thing that you can do, is to shorten the dosing interval.
This would mean instead of giving it twice a day you would give it three times a day. This causes there to be less peaks and valleys associated with it.
You can give a drug that prolongs the dopamine half-life.
You could give a direct acting dopamine agonist. These go directly to the brain and stimulate dopamine production in the brain.
What does on/off Mean in Parkinson’s disease?
When the person is on and the medication is working correctly, that the person is functional and you can hardly tell that there something wrong.
When the patient is off, the medication is not working and sometimes the patient can even be catatonic.
Levodopa, is capable of entering the brain via ________.
active transport
Remember, the problem with dopamine is that dopamine is a catecholamine.
Catecholamines cannot be actively transported into the central nervous system, but levodopa can.
Levodopa is a pro drug this means that it is not in its active form until after it gets into the brain and is metabolized. This makes it active.
What is a pro drug?
A pro drug is a drug that is inactive when it is given to the patient and the body metabolizes it and makes it become active.
What is the name of the enzyme that metabolizes dopamine?
Dopamine is metabolized by an enzyme called dopa-decarboxylase.
Dopa-decarboxylase metabolizes _______ and turns it into the active form of dopa.
levodopa
Why can’t you give dopamine and its active form to treat Parkinson’s disease?
You cannot give dopamine to treat Parkinson’s disease because it has a short half life, it cannot cross the blood brain barrier, and it cannot be absorbed.
What are the kinetics of levodopa?
The vast majority of levodopa is metabolized in the periphery because Dopa-decarboxylase is also in the periphery.
This causes an increase of dopamine in the periphery. This can cause problems such as tachycardia arrhythmias blood pressure issues.
How much Levodopa actually passes through the blood brain barrier?
Less than 2% of levodopa gets past the blood brain barrier so 98% of levodopa stays in the periphery.
What are the stimulant properties of dopamine?
At really low doses it can stimulate dopamine receptors in the periphery, at moderate doses it can stimulate beta-1 receptors, And at high doses it can stimulate Alpha-1 receptors.
Dopamine->Beta1->Alpha1
What are the adverse drug affects of levodopa?
It can cause nausea, dyskinesias, (it is used to treat dyskinesias but also can cause them) Grimaces, head bobbing, arrhythmias,tachycardia, psychosis such as vivid dreams, hallucinations, or cause the patient to become paranoid.
What is the most successful drug that is used for Parkinson’s disease?
Levodopa/carbidopa
What is the method of action of levodopa?
Levodopa is a pro drug that delivers dopamine to the brain.
What is the method of action of levodopa carbidopa?
carbidopa has no therapeutic effects alone. This means that you can give somebody a boat load of carbidopa and it will not do anything.
It inhibits dopa-decarboxylase in the periphery which allows more of the inactive form of levodopa to cross through the blood brain barrier where it is then metabolized into dopa, thus increasing the dopamine levels in the brain.
True or False
Carbidopa only works in the periphery and it cannot into the brain.
True
What are the kinnetics of levodopa/Carbidopa?
They allow reduction of levodopa by 75%.
This is because there is less levodopa being transformed to dopamine in the periphery so more of it gets into the brain because only the inactive form can get into the brain due to the blood brain barrier.
What are the side effects of levodopa/carbidopa?
The side effects that are produced by levodopa such as nausea, dyskinesias, grimacing, head bobbing, arrhythmias, tachycardia, are minimized by decreasing dopamine levels in the periphery.
What form does levodopa/carbidopa come In?
It comes in immediate release tablets, and now comes in extended release tablets.
What is the method of action of dopamine agonist?
They caused direct activation of dopamine receptors in the brain.
What are the drugs of choice for patients with Mild to Moderate symptoms of Parkinson’s Disease?
A dopamine agonist is considered the drug of choice for patients with mild or moderate symptoms of Parkinson’s disease. They are less effective than levodopa carbidopa but have some advantages.
What are the advantages of dopamine agonist?
They are not dependent on enzymatic conversion, which means that they are not pro drugs. And the affects don’t wane as much overtime.
Will the effects of Levodopa/Carbidopa last forever?
Nothing works as well as levodopa carbidopa for Parkinson’s disease, however the effects of levodopa carbidopa will decrease overtime (works 5-7 years) thus making it ineffective.
This is why you do not start a patient on levodopa carbidopa first you would try other methods such as dopamine agonist first.
Name two dopamine agonists.
Pramipexole and Robinirole
What is the method of action of Pramipexole and Robinirole.
They bind selectively to central dopamine receptors.
What are the adverse drug reactions of Pramipexole and Robinirole?
These do not cause movement disorders such as dyskinesia but they do cause nausea and hallucinations.
Besides Parkinson’s disease what is Pramipexole and Robinirole also used to treat.
These dopamine agonists are also used to treat restless leg syndrome.
MOA of COMT-
(catechol-O-methyltransferase) are responsible for the metabolism levodopa in the periphery along with dopadecarboxilase as well as catecholamines in general.
MOA of COMT inhibitors-
Work By blocking catechol-O-methyltransferase or COMP from metabolizing levadopa…..so that the levels of levodopa can rise in the periphery without having to increase the dose.
Name the COMT inhibitors.
Entacopone and Tolcapone
The Al Capones of Pharmacology
Actions and therapeutic usage of COMT inhibitors?
Indicated only for use with Levadopa. Prolongs the half life of Levadopa by about 50 to 75 percent.
Why can’t you give catecholamines orally?
You cannot give them or orally because they get metabolized too fast by enzymes such as COMT and Dopadecarboxilase so they don’t have the ability to be absorbed.
MOA of MAO- Monoamine Oxidase
is an enzyme responsible for breaking down some of our neurotransmitters. So if we block MAO our neurotransmitters will increase.
MOA of MAO-B- Monoamine Oxidase-B
is responsible for breaking down or metabolizing dopamine in our brain. It can metabolize endoginous dopamine as well as dopamine created by Levadopa.
So inhibitting MAO-B will essientially increase dopamine levels in the brain.
MOA of MAO-B inhibitors-
supress the metabolism of endoginous and dopamine created by levadopa in the brain thus allowing dopamine levels to rise without increasing the amount of Levadopa given.
MOA of MAO-A-
metabolizes norepinepherine and seritonin in the brain and is used to treat depression disorders.
Name a MAO-B inhibitor.
Selegiline
What is the MOA of Selegiline?
Suppresses the destruction of dopamine in the brain. This can be endoginous dopamine or dopamine created by Levadopa.
Central acting anticholinergic drugs means?
(simply means they are active in the brain)
Name a central acting anticholinergic drug.
Benztropine
What is the MOA of Benztropine?
Relieves symptoms of Parkinson’s disease by blocking muscarinic receptors in the brain, thus restoring balance. (brings normal level of Acetylcholine down to match depleted level of dopamine)
What are the side effects of Benztropine?
Opposite of muscarinic man. So dry mouth, blurred vision, tachycardia, constipation, urinary retention, dilated eyes ect,.
Name the 5 classes of Parkinson’s Drugs
Levadopa Levadopa/Carbidopa Dopamine Agonists COMT Inhibitors MAO-B Inhibitors
Carbidopa = ________% more Levadopa in the system
75
What medication would you give in adjunct to Levadopa/Carbidopa to a person who is having lots of On-Off Periods?
COMT Inhibitors (Entacopone, Tolcapone) because they prolong the 1/2 life of the dose, so that you do not have to raise the dose of Levadopa/Carbidopa.
What is the pathophysiology of Alzheimer’s disease?
It effects over 4.5 Million Americans, and kills over 400,000 people a year. It is the 4th leading cause of death behind cancer and strokes from hypertension. It is caused by:
Early: degeneration of neurons in the hippocampus, which serve in a significant role in memory formation. As these neurons begin to deteriorate your short term memory begins to fail initially.
Late: degeneration of neurons in the cerebral cortex, which is central to things such as speech, higher reasoning, perception, and higher functioning within the brain. As it continues to wrech the cerebral cortex within the brain, patients lose the ability to communicate, they lose bowel and bladder function wich results in death over time.
In Alzheimers Patients, what begins to fail initially? (EARLY STAGE)
Their short term memory.
This indicates that the disease progression is in the hippocampus
In Alzheimers Patients, What begins to fail when the disease process moves from the hippocampus to the cerebral cortex? (LATE STAGE)
degeneration of neurons in the cerebral cortex, which is central to things such as speech, higher reasoning, perception, and higher functioning within the brain.
As it continues to wrech the cerebral cortex within the brain, patients lose the ability to communicate, they lose bowel and bladder function wich results in death over time.
What are the 3 features of Alzheimer’s disease?
- Acetylcholine declines (can target from a pharmacological standpoint). Patients with Alzheimers have about 90% less Aceytalcholine than healthy patients. Acetylcholine is important in the role of memory formation, so by increasing this in the brain it could help them with memory loss.
- Beta-amyloid neuritic plaques (protein fragments in the brain seen upon autopsy)
- Neurofibrillary tangles- normally the brain is orderly. Autopsy of an Alzheimers patient’s brain shows a tangled mess.
What is the number 1 risk factor for Alzheimer’s disease?
Advanced age. It is also hereditary. 90% of the time patients are over the age of 65. After the age of 65, the risk factor doubles every 10 years.
What are the symptoms of Alzheimer’s disease?
Memory loss and confusion Impaired judgement Personality changes Aggressive combative Sundowning
What is sundowning?
Alzheimers patients do not sleep at night. They can be paranoid ect. When the sun goes down, they become wide awake. This is referred to as sundowning.
Which 2 of these symptoms are the classic cause of an Alzheimer’s patient to be placed into a nursing home?
Memory loss and confusion Impaired judgement Personality changes Aggressive combative Sundowning
Aggressive
Combative
How can a definitive diagnosis of Alzheimer’s disease be made?
A definitive diagnosis can only be made at death upon autopsy.
What is the only class of drugs used for Alzheimer’s disease that is FDA approved to help with memory loss?
Cholinesterase inhibitors.
What is the MOA of Acetylcholinesterase?
It metabolizes Acetylcholine
What is the MOA of Cholinesterase inhibitors?
Prevents the breakdown of acetylcholine in the brain by Acetylcholinesterase, thus increasing the availability at the muscarinic receptors.
What is the goal of therapy for Alzheimer’s disease?
To slow progression and Slow memory loss to try and preserve independant function.
What is the side effect of Cholinesterase inhibitors?
The elevation of Acetylcholine levels in the periphery.
As a result, it makes muscarinic man. (increased snot and spit production, heart slows down, beady eyes, bowels and urine increase, bronchoconstriction, makes asthma and peptic ulcer disease worse***)
What class of drugs do Cholinesterase inhibitors interact with?
Anticholinergic drugs,
Antidepressants, Tylenol PM
Name the specific Cholinesterase inhibitors
Tacrine
Donepezil
Rivastigmine
Galantamine
What is the MOA of Tacrine and its important characteristics?
Cholinesterase inhibitor, HEPATOXICITY, short half life requiring 4 times a day dosing. (not an ideal drug)
What is the MOA of Donepezil and it’s important characteristics? (Second Alzheimers Drug)
Cholinesterase inhibitor, VERY EXPENSIVE, dose is 5-10mg a day, Nonhepatoxic Better tolerated than tacrine
What is the MOA of rivastigmine?
IRREVERSIBLE Cholinesterase inhibitor
What is the MOA of Galantmine?
Reversible Cholinesterase inhibitor
What are the cautions for Galantmine?
Use with caution in pulmonary disease or COPD, avoid in severe hepatic or renal impairment.
True or False
Donepezil
Rivastigmine
Galantamine
Are all Cholinesterase inhibitors used to treat Alzheimers disease that are used interchangeably because there is not any evidence that one is any better than the other.
TRUE
What is the MOA of Memantine?
Modulates Glutamate or Glutamic Acid which is the major excitatory neurotransmitter in the brain
What drug is used for moderate to severe Alzheimer’s Disease?
Memantine
What is Glutamate?
It is the major excitatory neurotransmitter in the brain
What is the major neurotransmitter in the periphery?
Acetylcholine
What are some additional non-traditional Alzheimer’s drugs?
Vitamin E
Selegiline
NSAIDS (May help if taken at a young age)
Estrogens