Drug Therapy - Parkinson's & MS Flashcards
Which hormone/neurotransmitter is depleted in Parkinson’s Disease?
Dopamine
Diagnosis of Parkinson’s Disease
- Bradykinesia + 2 or more of the following:
- limb muscle rigidity
- resting tremor (attenuated by movement)
- postural instability
- micrographia
- Lack of other neurologic impairment
- Responsiveness to L-dopa
- Rule out drug-induced
What are the treatment goals of Parkinson’s Disease?
- Maintain patient independence, ADLs, and QOL
- Alleviate symptoms
- Minimize development of response fluctuations
- Limit medication-related adverse effects
Name the three classes of drugs used in pharmacologic therapy of PD.
- Dopamine Enhancers
- Dopamine Agoninsts
- Anticholinergics
Name the four sub-classes of Dopamine Enhancers.
- Levodopa/Carbidopa
- Amantadine
- MAO-B Inhibitors
- Selegiline & Rasagiline
- Catechol-o-methyltransferase (COMT) inhibitors
- Entacapone & Tolcapone
What is the most effective treatment of PD?
Levodopa/Carbidopa
What is the MOA for Levodopa/Carbidopa?
- Increases dopamine (DA) in the CNS
- Levadopa is the immediate precursor to DA, crosses the BBB (DA does not)
- Carbidopa inhibits peripheral conversion of levodopa to DA
Why do you titrate Levodopa/Carbidopa doses slowly?
To avoid peripheral adverse effects - nausea, vomiting, hypotension
What is the MOA for Amantadine?
NMDA receptor antagonist, blocks glutatmate transmission, promotes DA release, and blocks Ach
What is the concern with abrupt discontinuation of Amantadine?
Rebound Parkinson’s Disease
Name the MAO-B Inhibitors
- Selegiline
- Rassagiline
What is the MOA for MAO-B inhibitors?
- Prevent breakdown of DA via MAO-B
Which PD medication may be neuroprotective and neurorestorative?
Rasagiline
Why do you avoid MOA-B use with TCA, SSRI, SNRI, and meperidine?
- CNS toxicity
- autonomic instability
- HTN
- increased temp
- death
What is the MOA of COMT inhibitors?
Inhibit breakdown of levodopa
Name the COMT inhibitors
- Entacapone
- Tolcapone
What doe COMT inhibitors do to levodopa?
Increase the half life by 50% –> more continuous stimulation of dopamine receptors
What is the trade name of Levodopa/Carbidopa?
Sinemet
What is the trade name for Rasagiline?
Azilect
What is the trade name for Entacapone?
Comtan
What are the adverse effects of dopamine enhancers?
- agitation
- confusion
- insomnia
- psychosis
- headache
- dizziness
- orthostasis
- dyskinesias
- nausea
- vomiting
What is the benefit to dopamine agonists?
- May delay need for use of levodopa in early disease or decrease the dose of levodopa in advanced disease
What is the trade name of Pramipexole?
Mirapex
What are the adverse effects of dopamine agonists?
- confusion, dizziness, hallucinations, orthostasis, nausea, asthenia, syncope, peripheral edema
What happens when there is excess dopamine?
- CNS Effects
- confusion, hallucinations
- Systemic Effects
- GI complains, orthostatic hypotension
What is the MOA of anticholinergics in PD?
decreased cholinergic activity leads to improvement in tremor
What is often used as adjuvant therapy in early PD?
Anticholinergics - Benztropine (Cogentin)