Chapter 21 - Drugs for Parkinson's Disease Flashcards
Parkinson’s Disease - def
a disorder of the extrapyramidal system associated with disruption of neurotransmissions within the striatum.
Parkinson’s results in….
Dyskinesias - a disorder of movement.
Parkinson’s affects over ____ American.
one million.
Symptoms of Parkinson’s -
tremors, rigidity, postural instability, bradykinesia (slowed movement), psychological disturbances (loss of cognitive ability, depression, impaired memory.)
What is the cause of Parkinson’s?
Loss of dopaminergic neurons in substantia nigra.
Dopamine and GABA are inhibitory or excitatory?
Inhibitory
ACH is inhibitory or excitatory?
Excitatory.
What is the therapeutic goal of Parkinson’s Treatment?
Improve activities of daily living, because drugs can’t cure it - just try and get rid of the seconds.
Treatment strategy - Parkinson’s disease.
Regain balance of dopamine and ACH, by using agents that directly or indirectly activate dopamine receptors. You can also use agents that block ACH receptors.
What are the two major categories of drugs that treat PD?
Dopaminergic agents and Anticholinergic Agents.
Dopaminergic agents - def
promote activation of dopamine receptors. - Levodopa (Dopar.)
Anticholinergic Agents - def
prevent activation of cholinergic receptors. - Benzotropine (Cogentin.)
Dopaminergic Agents can….4
Promote dopamine synthesis, promote dopamine release, directly activate dopamine receptors, prevent dopamine degradation.
Anticholinergic drugs can…1
Block muscarinic cholinergic receptors in the striatum.
What are some Dopaminergic Drugs? (6)
Levodopa, Carbidopa, Amantadine, Selegiline, Bromocriptine, Bromocriptine, Pergolide
Levodopa - what does it do?
increase synthesis of dopamine.
Carbidopa - what does it do?
Inhibits peripheral decarboxylase enzyme, hence reduce degradation of Dopamine.
Amantadine and Selegiline - what do they do?
Promote release of dopamine
Bromocriptine and Pergolide - what do they do?
They activate dopamine receptors.
Anticholinergic Drug - 1 - and what does it do?
Benzotropine - Blocks ACH receptors.
What is a major side effect of Anticholinergic drugs?
Xerostomia - dry mouth.
Are levodopa and carbidopa combined in treatment?
Yes.
What is the drug of choice for PD treatment?
Levadopa.
If a patient fails to respond to levodopa, then what should happen?
We should ask ourselves rather or not PD is the correct diagnosis.
It only takes weeks to respond to levodopa - T/F?
FALSE. It may take months.
How can we minimize the gradual loss/wearing off of Levodopa? 3
Shorten the dose interval, give drug that increases the half-life (tocapone) and give a direct acting dopamine agonist.
We should eat a shit ton of protein with Levodopa - T/F?
NO! That could cause it! So avoid it!
What’s the MOA for Levodopa ?
Enters brain by active transport –> taken up by the few remaining dopaminergic nerve terminals that remain –> converted to dopamine by enzyme decarboxylase, which is enhanced by pyridoxine - vitamin B6!! –> balance ACH
Levodopa - Pharmacokinetics
Administered orally and rapidly from small intestine, and food delays absorption. Only 2% of dose reaches brain because decarboxylase enzyme metabolizes it.
Levodopa - side effects.
Nausea, vomitting, Dyskinesias, Hypotension, Psychosis
Drug interactions for Levodopa -
don’t mix it with antipsychotic drugs (drugs that block dopamine receptors), MAO inhibitors, anticholinergic drugs, or foods with high protein.
Carbidopa has a ton of adverse effects - T/F?
False! None
Why is PD not treated with straight up dopamine? 2 Reasons.
Dopamine cannot cross the Blood brain barrier and it has a short half life.
