PD Flashcards
1
Q
PD symptoms
A
resting tremor, rigidity, bradykinesia, impaired balance, mask-like appearance, speech difficulties, cognitive deficits*
2
Q
PD is characterized by…
A
- PD is characterized by a loss of dopaminergic neurons in the substantia nigra**: Gradual loss of darkly pigmented, dopamine-releasing neurons in the SN pars compacta in the midbrain
- presence of Lewy bodies in the various regions of the brain: Enriched with fibrillar forms of the protein α-synucelin, Aggregation of α-synuclein: Stage 1: Lower brainstem**, Stage 2: Raphe, Stage 3: SN (-> classic PD symptoms), Stage 4: mesocortex/thalamus, Stage 5: neocortex, Stage 6: entire neocortex
3
Q
Neurotoxic/ Neuroprotective mechanisms in PD
A
- Mitochrondria: electron chain dysfunction increase build up of ROS
- α-synuclein is oxidized and aggregates
4
Q
Midbrain
A
- SN pars compacta provides input to the basal ganglia and supplies dopamine
- Undergoes neurodegeneration in PD
5
Q
Basal Ganglia
A
- Striatum (caudate nucleus, putamen*)
- Globus pallidus (external and internal segments)
- Dopamine Signaling: Direct Pathway: involving D1 receptors in the striatum; Indirect Pathway: involving D2 receptors in the striatum; Effect of thalamocortical signaling is disrupted in PD**
6
Q
antimuscarinics
A
- adjunct therapy
- Loss of dopamine = increase in cholinergic activity** (sort of compensation)
- Cholinergic antagonists (antimuscarinic) can partially compensate for over activity
7
Q
LDOPA
A
- gold standard for PD therapy
- Precursor of dopamine, but needs to be converted in SN, not periphery
- L-DOPA crosses BBB, dopamine does not cross BBB
- Carbidopa is a peripherally acting DOPA decarboxylase inhibitor** to prevent conversion of L-DOPA -> dopamine in the periphery
- Carbidopa does not penetrate BBB, so does not inhibit conversion in SN
- Challenges: In PD there are less nigral dopaminergic neurons to convert L-DOPA to dopamine over time, Dyskinesias : aberrant and exaggerated motor effects, Address these challenges by using dopamine receptor analogs as a possible alternative
8
Q
DA receptor agonists
A
apomorphine, ergolines, nonergolines
9
Q
apomorphine
A
(mixed D1/D2 agonist): used in late-stage PD; use is limited due to N/V
10
Q
ergolines
A
bromocriptine, pergolide
- Bromocriptine: used as adjunct to L-DOPA to be able to lower dose
- Pergolide: very potent D2 agonist used to treat PD (no longer in US)
11
Q
nonergolines
A
ropinirole, pramipexole, rotigotine
- D2/D3 agonists with fewer side effects than ergolines
- Generally used as monotherapy for early-stage PD
- Rotigotine offered in a transdermal patch
12
Q
MAOB inhibitors
A
selegiline and rasagiline**
- These drugs inhibit the oxidation of dopamine to DOPAL by MAO-B
- Both drugs can initially be used to delay first use of L-DOPA or as adjuncts to L-DOPA
13
Q
dopamine metabolism inhibition
A
COMT inhibitors (entacapone, tolcapone)
- Inhibition of COMT by entacapone decreases metabolism of L-DOPA in the periphery, allowing more to reach the brain
- Tolcapone works in CNS to increase CNS levels of dopamine from L-DOPA
- Entacapone can increase duration of effect
14
Q
propargylamines
A
R2N-CH2-C—CH
15
Q
PD motor symptoms
A
tremor, bradykinesia, rigidity, Parkinsonian gait