PD Meds Flashcards
What are the 2 types of drugs used for PD?
- Dopaminergic agents: activate dopamine receptors
- Anticholinergic agents: block acetylcholine
What drugs treat mild symptoms?
MAOB-inhibitor (Dopaminergic agents):
-selegiline or rasagiline
What drugs treat severe symptoms?
Levodopa with carbidopa and possibly with entacapone
percursor to dopamine
levodopa
What happens to Levodopa over time?
- benefits diminish over time
- gradual wearing off: prevent by shortening dosing interval and give meds that prolog levodopa half life
- Abrupt loss: “on-off” phenomenon, lasts hours to minutes
Explain the mechanism of action of Levodopa.
- crosses BBB
- converts to dopamine in CNS and periphery
- activates post-synaptic dopaminergic receptor; increases dopamine at receptor site
- administer with decarboxylase inhibitors to increase bioavailability
What are some important adverse affects of Levodopa?
- difficulty with impulse control
- insomnia and nightmares
- darkens sweat and urine
- dyskinesias: involuntary movements
- anxiety, hallucinations, paranoia
What are the drug interactions with Levodopa?
- 1st gen antipsychotics
- MAOIs
- Anticholinergic drugs (benztropine (congentin) and Trihexyphenidyl (Artane).
What is the mech of action for carbidopa?
- inhibits decarboxylase leaving more levodopa available in the CNS
- does not allow metabolism in GI or peripheral tissue
- but then is unable to cross BBB so it won’t prevent conversion of levodopa to dopamine
What are the advantages of carbidopa?
- levodopa dosage can be reduced
- reduces N/V and cardiovascular response (dysrhythmias) caused by levodopa
What is one disadvantage of the levodopa and carbidopa combination?
abnormal movements and psychiatric disturbances can occur sooner and be more intense
What is sinemet?
Levodopa and Carbidopa
- take on empty stomach
- food reduces absorption
First line drug for PD for mild to moderate symptoms.
dopamine agonists
What are the 2 dopamine agonists (drugs)?
pramipexole (Mirapex)
apomorphine (Apokyn)
What are the serious side effects of dopamine agonists pramipexole (Mirapex) apomorphine (Apokyn)?
hallucinations
day time sleepiness
postural hypotension
What are the 2 types of dopamine agonists?
- derivatives of ergot: less selective
- non-ergot derivatives: highly selective for dopamine receptors
When is pramipexole (Mirapex) used?
- early on in PD used alone for motor improvement
- late in PD used with levodopa to reduce levodopa dosage
What else is pramipexole (Mirapex) used for?
RLS
What are the adverse effects of pramipexole (Mirapex) alone and with levodopa?
- monotherapy: nausea, dizziness, insomnia, constipation, hallucinations
- combined with levodopa: orthostatic hypotension, dyskinesias, increase in hallucinations, compulsive behaviors,
What are the characteristics of the non-ergot (highly selective) dopamine agonist
apomorphine (Apokyn)?
- used during “off” periods to treat hypo mobility for advanced PD pt’s
- not for routine PD management (no given PO)
- derivative of morphine but devoid of typical opioid effects
What are the adverse effects of apomorphine (Apokyn)?
- injection site reaction
- hallucinations
- drowsiness
- dyskinesias
- rhinorrhea
- N/V
- sleep attacks
- rare: priapism
What are the 2 COMT inhibitors and what do they do?
- entacapone (safer and more effective)
- Tolcapone
- inhibit metabolism of levodopa in the periphery and GI
- prolongs time levodopa is available to the brain
What are some important adverse effects of entacapone (Comtan)?
-yellow orange discoloration of urine
When are anticholinergics (benztropine (congentin) and Trihexyphenidyl (Artane) used for?
-used for second line therapy for tremor
These block cholinergic receptors in the periphery.
(benztropine (congentin) and Trihexyphenidyl (Artane)
