Parkinson's Flashcards
Parkinson’s pearls
- Dopamine deficiency (loss of balance with ACh)
- Loss of dopaminergic cells in SNc/basal ganglia AND formation of Lewy bodies
- Mostly male
- Average age of onset = 62
- Rural life increases risk (pesticides?)
- INVERSE correlation between smoking and caffeine for PD development
- 30-80% of nigral cell death before disease manifests
Diagnosis
Bradykinesia (slow/difficult movement) and at least 1:
- Limb rigidity (usually starts unilateral)
- Resting tremor (usually starts unilateral)
- Postural instability
What drugs can cause parkinsonism?
- 1st generation antipsychotics
- Antiemetics (reglan, compazine)
Anticholinergics
Benztropine, Trihexyphenidyl
- Avoid in >65 y/o
- Linked to cognitive decline/impairment
Levodopa
- Gold standard*
- Precursor to dopamine, crosses BBB
- Take on empty stomach to maximize abs.
- Be consistent with administration (w,w/o food)
- CI in breast-feeding, closed-angle glaucoma
- ADE dyskinesia, GI, orthostatic HTN, waste discoloration, psychiatric disturbances
- Stops working over time**
- DDI with MAOis, iron, pyridoxine, DAs
- Start 200-300 mg/day in divided doses
Carbidopa
- Does not cross BBB
- useless alone, only helps deliver levodopa to brain
- CI in pregnancy, lactation
- Maintain 70-100 mg/day when in L-dopa combo
Sinemet
- 1:10 or 1:4 ratio of carbidopa/levodopa
- Sinemet CR has decreased bioavailability compared to IR (give 25% more)
- CR has decreased off time, but delayed onset (can supplement IR)
- Start decreasing frequency to switch IR -> CR
Duopa
- Carbidopa/Levodopa intestinal gel - PEG-J tube
- Mostly for advanced PD to achieve more consistent L-Dopa levels (less off time)
- Pts must convert to oral IR first
Inbrija
- Levodopa powder for inhalation
- Not replacement for PO Carb/Levo but used for off episodes
- Avoid in respiratory disorders
COMT inhibitors
Tolcapone, Entacapone, Opicaopone
- prevents breakdown of L-Dopa
- no effect in absence of L-dopa
- DI with non-selective MAOis
Entacapone (Comtan)
- Shorter t1/2
- Give 200mg with EACH DOSE of levodopa/carbidopa (up to 8 times/day)
- May cause brown/orange urine
- Stalevo is a combo product of entacapone/levodopa/carbidopa
Tolcapone (Tamsar)
- Contraindicated in hepatic disease
- Rarely used due to hepatocellular injury (inc. LFTs)
Opicapone (Ongentys)
- New (4/2020)
- Absorption decreased with big meal
- Once daily dosing, do not eat within 1 hour
MAOis
Selegiline, Rasagiline, Safinamide
- Decrease breakdown of dopamine
- Increase L-Dopa peaks, less dosing needed
- Can be used as monotherapy or adjunctive
- Tyramine reaction (cheese, wine)
Selegiline
- Labeled indication for adjunct, but data supports monotherapy
- 3 active metabolites, lingers for weeks
- ADE insomnia, jitteriness
Rasagiline (Azilect)
- Potentially DISEASE MODIFYING***
- 0.5 mg QD with levodopa
- 1 mg QD for monotherapy
Safinamide (Xadago)
- Adjunctive therapy for wearing off sx.
- Newer agent
- Na and K channel blocker, dec. glutamate
- 90% renal
- hepatic metabolism
Amantadine
- MOA poorly understood
- Decrease rigidity, tremor, bradykinesia, and L-Dopa-induced dyskinesia**
- Adjust dose with renal impairment
- ADE peripheral edema, livedo reticularis
Dopamine agonists
Apomorphine, Pramipexole, Ropinirole, Rotigotine
- Can be used as monotherapy
- Reduce risk of developing motor complications compared to L-Dopa
- Used as adjunct for L-Dopa loss of effect
- Non-motor ADE more common compared to L-Dopa
- Impulsive behaviors, psychosis, N/V, vivid dreams, orthostatic HTN, daytime sedation
Pramipexole (Mirapex)
- Renal dosing
Ropinirole (Requip)
- CI in hepatic disease
- Do not abruptly discontinue, taper
- CYP1A2 DIs
Rotigotine (Neupro)
-Transdermal patch
- Causes skin burns in MRI, caution with heat
- Careful with sulfite sensitivity (has metabisulfite)
- Application site reaction
Apomorphine (Apokyn)
- Used in advanced PD “as needed” for off episodes (not monotherapy)
- 2mg SC test dose under medical supervision required, monitor BP
- Pre-treat with antiemetic (NOT 5HT3 -> hypotension)
- Rapid onset of action
- 40 minute terminal t1/2
Istradefylline (Nourianz)
- Adenosine A2A receptor blocker (motor inhibition is caused by overactive adenosine A2A)
- Used for off episodes of carbidopa/levodopa (adjunct)
- Dosage adjustment for concomitant tobacco smoking
- DDi with CYP3A4
