Parkinsons Disease Flashcards
Role of Parkinsons Meds
Designed to normalize dopamine activity in the BG
What is the primary drug used to treat PD?
Levodopa- almost always improves the symptoms associated with parkinsonim (especially bradykinesia and rigidity)
Levodopa mechanism of action
Levodopa is taken orally, absorbed through the GI tract and converted into dopamine by the enzyme dopa decarboxylase. Any thing converted into dopamine outside of the brain will be useless- only small amounts actually make it to the brain before being converted
Why would taking dopamine orally or parenterally not be effective for treating PD?
It cannot cross the BBB and thus would never reach the brain
Why would patients need to take such large quantities of levodopa?
Since so much of it is converted to dopamine in the periphery and is rendered useless
Why is Carbidopa important?
Carbidopa inhibits the enzyme that converts levodopa into dopamine within the periphery which allows for more levodopa to reach the brain before being converted
What is a Sinemet?
A manufactured pill containing both levodopa and carbidopa- these 2 drugs are almost always given together in order to allow for a smaller dosage of levodopa
Side effects of Levodopa
-GI problems
-cardiac problems
-orthostatic hypotension
-dyskinesias
-behavioral changes (depression, anxiety, confusion, psychosis)
When does Levodopa start to become less effective?
After prolonged use for a prolonged period of time- about 3-4 years
What is the End of Dose Akinesia?
When the drug’s effectiveness wears off prior to the next dose
-can be resolved by adjusting the timing and quantity of doses
What is the On-Off Phenomenon?
When the effectiveness of levodopa suddenly and spontaneously decreases which results in worse parkinsonian symptoms due to a drop in dopamine levels- known as the “off” phase
-can occur repeatedly throughout the day
What does Freezing mean?
When a patient stops talking and appears to be frozen in an upright position- reason unknown
What is a drug holiday and what is the overall goal?
Patient is gradually removed from all parkinsons meds for 3 days-3 weeks while being closely supervised when their drugs are no longer effective or their side effects become too severe
Goal: to let the body recover from any drug toxicity or tolerance due to prolonged usage
Effectiveness of a Drug Holiday and Risks associated
50-70% of people benefit from them, however there are risk associated such as- DVT, PE, pneumonia, and other impairments because of immobility
Which drugs are used for Parkinsons Disease?
-Levodopa
-Carbidopa
-Dopamine agonists
-Anticholinergic drugs
-Amantadine
-MAO-B Inhibitors
-Catechol-O-Methyltansferase Inhibitors
When are dopamine agonists typically used?
Typically used with levodopa when it starts to become less effective or the patient has developed end-of-dose akinesia or On-Off Syndrome
Which drugs alleviate acetylcholine to help with PD tremors and rigidity?
Anticholinergic Drugs- most effective when used with levodopa
-causes anticholinergic side effects
What is the purpose of Amantadine?
Taken with Levodopa to help reduce dyskinesias and other motor symptoms that can occur with Levodopa
How do MAO- Inhibitors work?
These drugs inhibit the enzyme MOA-B from breaking down dopamine which allows for dopamine to have a longer effect in the brain
What is the purpose of Catechol-O-Methyltansferase (COMT) Inhibitors?
To inhibit the enzyme COMT which converts levodopa in within the periphery to an inactive metabolite. This allows for more levodopa to reach the brain to be converted into dopamine
Which drug can be used in the early stages of PD to prolong having to take Levodopa?
MAO-B Inhibitors- thought to slow the progression of PD
What is Stalevo?
A combination drug of levodopa, carbidopa, and COMT inhibitor
Which Parkinsons Drugs should be used for initial treatment?
Dopamine Agonists or MAO-B Inhibitors
When should patient begin taking Levodopa?
Should be incorporated into drug regimen as their disability increases
What is Deep Brain Stimulation?
Surgically implanted electrodes into the deep brain structures where high frequency stimulation may help normalize neuronal activity within the BG- helps to resolve motor and non-motor PD symptoms
