movement disorders pharm Flashcards
1
Q
Pathophys of parkinson’s
- tx goal?
A
- normally high conc of dopamine in basal ganglia is reduced in parkinsonism
- pharm attempts to restore dopaminergic activity in the brain is the goal of tx
- tx goals also include management of SEs of dopaminergic therapy
2
Q
Levadopa/carbidopa (sinemet)? Use?
A
- GOLD STD of Tx!!!!
- traditionally used first line, but selegaline often given to pts with mild parkinsons
- tends to be less effective with prolonged use in some pts
- effectiveness greatly decreases after 3rd year of tx and may return to pretx levels in 6-7 years
- completely or partially relieves akinesia, rigidity, and tremor in about 80%
- preferred initial tx in pts over 70, particulary those with dementia
3
Q
What sxs will sinemet tx?
A
- may be useful to tx dysphasia, seilorrhea, seborrhea, and improve fxnl ability and otehr secondaray motor sxs
- most effective against rigidity and slowness
- less benefit for tremor, balance and gait
- produces a general altering response, increases vigor, and sense of well-being
4
Q
Is Sinemet neuroprotective?
A
- no, concern is taht prolonged use of levodopa may directly hasten degeneration of dopamine neurons in substantia nigra by promoting the generation of free radicals and oxidative stress is basis for delaying use of levodopa in tx of PD
- but it is very effective!
5
Q
MOA of Sinemet?
A
- levodopa is immed metabolic precursor to dopamine, penetrates the brain, where it is decarboxylated into dopamine (1-5% of admin levadopa enters the brain, rest is metabolized extracerebrally by decarboxylation to dopamine)
- Carbidopa is decarboxylase inhibitor, peripheral metabolism is reduced and plasma levels of levadopa are higher and more is available to enter the brain
- thus combo produces better effects
- effective but short acting
6
Q
AEs of sinement?
A
- phyiscal: low BP arrhythmia GI effects (when levodopa used alone) hair loss dyskinesias (80%)
psych/mental: confusion anxiety vivid dreams hallucinations
prevention: try giving smaller doses more frequently, reduce or stop evening dose if severe psych effects occur
7
Q
What is wearing off effect of sinement? How is this prevented?
A
- may occur w/in 4-6 years of tx
- initially may be bradykinesia or tremor in am b/f next dose (motor fluctuations - alt b/t periods of being on, during which pt enjoys a good response to med, and being off during which pt experiences underlying sxs of PD)
- on-off effect in 15-20%
- sometimes sxs switch back in forth w/in minutes or even seconds - this transition may follow sxs as intense anxiety, sweating and rapid heartbeats
- prevention:
mult small doses on empty stomach, liquid form, controlled release formulation
8
Q
CIs and precautions in sinemet?
A
- CIs: concurrent use with MAOIs psych pts angle closure glaucoma hx of melanoma (dopamine driven)
- precautions:
cardiac disease
PUD
9
Q
Why does wearing off effect occur with sinemet?
A
- theories:
disease progresses beyond ability of levodopa to control it
some pts become tolerant to prolonged exposure to dopamine and at same time disease is progressing
brain’s own dopamine neurons become incapable of storing dopamine and when levadopa wears off - little or no natural dopamine remains
levadopa itself accel disease by producing oxygen free radicals, unstable particles that increase injuries to brain and dopamine degradation
10
Q
How can we prevent the wearing off effect?
A
- maintain consistent level of dopamine as possible
- unfortunately, levadopa is poorly absorbed and may remain in stomach for long time
- thus it’s beneficial for add of dopamine agonists, MAOBs and COMT inhibitors to the regimen
11
Q
What class is Selegiline (Elderlyl, Zelapar)? MOA?
A
- MAO-B inhibitor
- stops breakdown of dopamine
- enhances peak levadopa levels
- may have neuroprotective properties by reducing oxidative metabolism of dopamine
- lipophilic and penetrates BBB rapidly
- 5 mg w/ breakfast and 5 mg with lunch, shouldn’t take later in day due to insomnia
12
Q
What class is Rasagiline (Azilect)? MOA?
A
- MAO-B inhibitor
- more potent than selegiline
- stops breakdown of dopamine
- enhances peak levadopa levels
- may have neuroprotective properties by reducing oxidative metabolism of dopamine
- lipophilic and penetrates BBB rapidly
- 1 mg qd when used alone, .5 mg qd when used w/ sinemet
13
Q
Adverse effects of all MAO-Bs?
A
- insomnia
- jitteriness
- dykinesias
- orthostatic hypotension
- may enhance levadopa adverse effects
14
Q
Cautions and CIs with MAO-B inhibitors?
A
caution with: impaired liver fxn CV disease cerebral vascular disease seizure disorder hyperthyroidism diabetes psych disorders
CIs: concurrent use with TCAs, SSRIs and demerol
15
Q
When are MAO-B inhibitors used first line?
A
- in pts with mild disease to slow progression and delay need for levodopa (has neuroprotection)!!!
- used as adjunctive therapy to decrease “wearing off”
16
Q
Class of dopamine agonists?
A
- bromocriptine (parlodel) and pergolide (permax): older agents, and ergo derivatives (not used anymore)
- pramipexole (mirapex) and ropirinole (requip) - newer agents, not ergo derivatives
17
Q
MOA of dopamine agonists?
A
- stim dopamine receptors in substantia nigra
- effective in delaying motor complications during first 1-2 years of tx
- studies also report improvement in impaired movements and disability
- may delay the need or increase of dose of sinemet
- **mod sxs in younger pts may be tx with dopamine agonists first line
18
Q
AEs of dopamine agonists?
A
- drowsiness and sleepiness
- Nausea, and constipation
- HA
- orthostatic hypotension
- nasal congestion
- nightmares, hallucinations, psychosis
- dyskinesias
- older meds used less frequently due to higher incidence of adverse effects
19
Q
CIs of dopamine agonists?
A
- pts with psychotic illness
- pts with recent MI
- pts with PUD
- ergo derived best avoided in pts wtih PVD
20
Q
Apomorphine (apokyn) class? use?
A
- dopamine agonist
- to tx acute episodes of hypermobility or freezing
- given SQ
- very expensive
- cause profound nausea, must be given with antiemetic (no zofran or kytril can be used with this drug, must use other antiemetic) - both block dopamine
21
Q
AEs of apokyn (apomorphine)?
A
- N/V
- yawning
- dyskinesias
- sedation
- dizziness
22
Q
COMT inhibitors class?
MOA?
A
- Entacapone (comtan), tolcapone (tasmar)
- MOA: increase concentration of existing dopamine in brain by inhibiting breakdown
- diminishes peripheral metabolism
- improve motor fluctuations related to wearing off and improve on time
- reduce need for levadopa/carbidopa
- **only indicated in pts taking levodopa/carbidopa (often need to decrease levadopa/carbidopa)
23
Q
AEs of COMT inhibitors?
A
- involuntary muscle movements
- mental confusion and hallucinations
- cramps, nausea, diarrhea
- insomnia
- HA
- urine discoloration
24
Q
Dosing of COMT inhibitors?
A
- 200 mg w/ each levadopa/carbidopa dose (max: 8 tablets/day)
- try for 2-3 weeks and if no benefit seen - stop meds due to SEs - going to happen, pts don’t tolerate them - not worth it!
25
Q
Use of Amantadine? MOA?
A
- MOA: potentiates dopaminergic fxn by inluencing the synthesis, release or reuptake of dopamine
- useful for early mild sxs
- benefits may be short-lived but does favorably influence akinesia, rigidity. Not really effective with tremor
- used as adjunct therapy
- not confirmed - that there are true benefits
26
Q
AEs of amantadine?
A
- sedation
- vivid dreams
- dry mouth
- depression
- hallucinations
** caution with renal dysfxn
27
Q
Class of anticholinergic acetylcholine-blocking drugs?
Use?
A
- trihexyphenidyl (artane)
- benztropine )cogentin)
MOA: blocks acetylcholine (inhibits dopamine) - so it’s blocking inhibition of dopamine
use:
-primarily for tremor
-helps with rigidity
-no effect on akinesias
-drugs differ in potency
-if pt doesn’t respond to one drug, a trial with another is warranted
28
Q
AEs of acetylcholine blocking drugs?
A
- CNS: drowsiness mental slowness restlessness confusion hallucination
- systemic: dry mouth blurred vision mydriasis urinaray retention N/V constipation palpitations, arrhythmias IOP
29
Q
CIs of acetylcholine-blocking drugs?
A
- BPH
- obstructive GI disease
- angle closure glaucoma
30
Q
What are some investigative neuroprotective agents?
A
- coenzyme Q: antioxidant impt for cellular energy (not very beneficial)
- Budipine and other glutamate blockers: glutatmate is potent nerve cell killer
- cannabinoids: may have nerve protecting properties
- genetic therapy: admin genes that produce dopamine to protect or heal damaged nerve cells
31
Q
When do you decide to begin therapy in PD?
A
- determined by degree to which pt is functionally impaired
timing of this varies greatly among pts but is influenced by number of factors:
-effect of disease on dominant hand
-degree to which the disease interferes with work, ADLs, or social or leisure function - presence of sig bradykinesia or gait disturbance
- personal philosophy regarding use of drugs
- sx tx of mild parkinsons is probably best avoided until there is some degree of disability or sxs begin to have sig impact on ADLs
32
Q
What meds are considered first?
A
- when tx becomes necessary, selegiline has neuroprotective affects, is often considered first. Esp in mild cases early on
- a trial of amantadine or an antimuscarinic drug (or both) may be worthwhile
- as disease progresses, dopaminergic therapy becomes necessary: use dopamine agonists, either alone or in combo with low dose levodopa/carbidopa therapy
- when on-off phenomena starts - a trial of COMT is worthwhile
- Have to make tx plan specific to PD pt - and degree of disease and progression
33
Q
Emerging therapies in PD?
A
- stem cell therapy
- gene therapy
- immunotherapy
- other pharm trials
