Parkinsons Flashcards
Dyskinesia occurs when patients get too much dopamine
T
Decrease levodopa dose; add dopamine agonist ( amantadine ) they cause fewer dyskinesias than levodopa
When you think Parkinson’s we use medications like anticholinergics. Why do we use anticholinergics?
Recall balance of ach and DA. If DA levels are low and we give an anticholinergic to decrease Ach we bring the levels to balance.
The main reason we use an anticholinergic is if patient has extrapyramidal side effects ( due typical and atypical antipsychotics and if we have a younger patient that has tremor. **Problem with anticholinergic medications is we cant use in BPH, bladder neck obstruction, myasthenia gravis, glaucoma we can not use anticholinergics here.
•diphenhydramine : ( Benadryl ) : if no benztropine around to tx extrapyramidal you can use this ( comes IM /IV )
•Trihelphenidyl : ( Artane ) : PO
•Benztropine ( Cogentin ) : DOC for drug induced extrapyramidal ( acute dystonic reaction ) ( IM /IV /PO)
dopamine precursors
Levodopa : you never give levodopa alone. Sinemet : carbidopa levodopa
MAOI- B
MAO enzymes metabolize seratonin, dopamine, and epinephrine. Some are more selective MAOI-B
- selegiline ( eldepryl/ zelapar for Parkinson’s ) ( recall selegiline for depression EMSAM patch once daily )
- Rasagiline ( azilect )
- Safinamide ( xadago ) -
Dopamine Reup
Amantadine : pretty mild but does increase dopamine and has anticholinergic effect to it.
Dopamine agonist
- bromocriptine ( parlodel )
- pramipexole ( mirapex/ER )
- rotigotine ( Neupro ) - a Patch
- Ropinirole ( Requip/ XL )
- Apomorphine ( apokyn )
COMT inhibitor
COMT Inhibitors : never want to give a COMT inhibitor alone. You give this patients on sinamet ( levodopa Carbidopa ). If you need to allow more of the levodopa not to be metabolized and more to stay in the BBB you can add a COMT inhibitor.
* Stalevo: Carbidopa + levodopa + ENTACAPONE
COMT inhibitor:
• Entacapone
• Tolcapone ( major hepatotoxicity so mainly we use entacapone )
DOC in tx of antipsychotic induced pseudo Parkinson’s
Anticholinergic drugs
Additive anticholinergic agents
DDIs
-atropine
-scopolamine
-TCA’s
-Dicyclomine ( Bentyl )
- Hyoscyamine
Additive CNS side effects: confusion, hallucination, memory impairment
-anti SLUDGE
Tachycardia , constipation
Sinemet
Carbidopa / Levodopa : carbidopa allows levodopa to NOT BE metabolized in the periphery so you can have more in BBB
First line agent with older patients
CR, ER , ODT
Need at least 75 mg of carbidopa a day to block enzyme ( dopa decarboxylase in periphery )
T so you can benefit of increase of dopamine in brain.
Some patients need up to 200 mg carbidopa a day
Rytary
IR + ER beads of ( carbidopa / levodopa ) in a capsule. Works within 1 hour and lasts 6 hours
If you go from non CR carbidopa + levodopa to CR you must _____ dose by _____
Increase dose by 10 - 30%
What is the rate limiting factor of using carbidopa levodopa ?
Dyskinesia ( 80% at 1 year : major limiting factor in dosing )
carbidopa levodopa counseling point. With food?
Avoid high protein. Intestinal protein will compete with levodopa and decrease levodopa’s effectiveness. Take protein at a different time. Take with food for GI effects but less protein
Drugs to avoid in patients with Parkinson’s?
Drugs that decrease dopamine
1) antipsychotics : haldol : decreases dopamine
2) Reglan : blocks dopamine
3) phenothiazines ( prochlorperazine ) : blocks DA
4) avoid combination of non selective MAOIs: increase DA, NE nad seratonin: too much dopamine in system: HTN crisis
Also caution with MAOI ( Linezolid , tedizolid , Procarbazine )
5) iron : chelates to levodopa
6) pyridoxine ( VB6 ) not a problem with added carbidopa
Cyclobenzaprine chemically structurally looks like…
TCAs which looks like carbamazepines.
DDI similar. Dont give with MAOIs
Amantadine
Symmetrel
An antiviral drug that acts as antagonist at N-methyl-D- aspartame ( NMDA ) receptors
Used to be used for influenza A however due to resistance no longer recommended.
•MOA : it increases dopamine and is slightly anticholinergic for use in Parkinson’s
100% renally excreted
If younger patient gets parkinsons you should start with
Dopamine agonists instead of carbidopa and levodopa. Why? Bc carbidopa levodopa have a high chance of dyskinesia so thats why we wait to use those later on disease state.
You can use dopamine agonist in combination with other medications
Anytime you increase dopamine you have increase chance of orthostatic hypotension
T
Yes because when you increase dopamine you have increased vasodilatory effects so you get more orthostatic hypotension.
Also with dopamine agonists you need to worry about dose dependent peripheral edema. May increase chance of heart failure.
When you increase dopamine you decrease prolactin
T and vice versa
Recall antipsychotics for schizophrenia ( Aripiprazole, Risperidone, paliperidone, asenaphine these all block dopamine so increases prolactin. Worst was Risperidone )
So in schizophrenic patients I’m blocking dopamine ( increase prolactin ) but in Parkinson’s patient I’m increasing dopamine ( decrease prolactin )
Thats why bromcriptine ( parlodel ) a parkinsons drug also used for hyperprolactinemia
When you increase dopamine you decrease prolactin
T and vice versa
Recall antipsychotics for schizophrenia ( Aripiprazole, Risperidone, paliperidone, asenaphine these all block dopamine so increases prolactin. Worst was Risperidone )
So in schizophrenic patients I’m blocking dopamine ( increase prolactin ) but in Parkinson’s patient I’m increasing dopamine ( decrease prolactin )
Thats why bromcriptine ( parlodel ) a parkinsons drug also used for hyperprolactinemia
Apomorphine causes severe nausea. Can you use Ondansetron?
NOOO
Ondansetron and other serotonin agonists and apomorphine can causes severe hypotension and loss of consciousness
Prochlorperazine and metoclopramide should be avoided in Parkinson’s patients because
We want to avoid dopamine antagonists in parkinsons
