Parkinson's Pharmacology Flashcards
What is the first line Tx in Parkinson’s?
Levodopa is the first Line for PD, and is used in combination with Carbidopa (decarboxylase inhibitor)
Why is Carbidopa given with levodopa?
Inhibits breakdown of levodopa in peripheral tissue (outside the Blood Brain Barrier).
What are some of the adverse effects?
Nausea, vomiting
Postural Hypotension
Tachycardia.
Domperidone is preferred over metoclopramide as an antiemetic to treat Levodopa - induced nausea and vomiting because..?
Domperidone does not cross the Blood Brain Barrier.
Vomiting centre is outside the BBB.
What are some slowly developing effects with Levodopa?
Motor complications, including Response fluctuations - “wearing off”.
The “On-Off effect”
Dyskinesia’s
Lost a disproportionate amount of money in online betting. Which could be the offending medication?
Rotigotine (Dopamine Agonist)
- Causes a dysregulation of the reward pathway.
Adverse effects of Dopamine Agonist
- Excessive sleepiness
- Psychosis - Hallucinations / delusions.
- Impulse control disorders
When do we prefer Levodopa or Dopamine Agonists in Parkinson’s?
Prefer Levodopa in px > 70 yrs.
Prefer DA’s in px < 70 (unless have any predispositions to adverse effects of DA’s)
What are some Central Anticholinergic Drugs?
Orphenadrine, Benzatropine,
Benzatropine used to alleviate Extrapyramidal effect caused by antipsychotic medications.
What are some classical features of Parkinson’s?
Asymmetrical
What are the features of Drug-Induced Parkinson’s?
- ## Symmetrical
What causes Drug-Induced Parkinson’s?
- Anti-psychotics (promethazine, haloparidol)
- Anti-emetics (Procloperazine)
Why is drug-induced Parkinson’s not treated with levodopa?
Because receptors are blocked and not available.
What happens in Drug-induced Parkinson’s?
Drugs which cause blockage of the domaminergic system (dopamine receptor blockers) mimic the traits of Parkinson’s disease, such as tremors and postural instability.
Patients should be advised to take Levodopa with meals to avoid gastric side effects.
Yes.
Levodopa causes more daytime sleepiness than Rotigotine.
No, Daytime sleepiness is more common wit DA’s.
Patients started on Entacapone should have monthly checks of LFTs due to its hepatotoxic potential.
No, (precursor of Entacapone used to cause this by Entacapone does not)
When is Amantadine (Antiviral + Antiparkinsonian drug) for Drug-induced Parkinson’s.
If Anti-cholinergics were contraindicated this would be the next line.
Primarily an antiviral - Also has antiparkinsonian properties
What medication can be given in a Parkinson’s Freeze?
Apomorphine (non-selective Dopamine Receptior Agonist)
Parkinsons Freeze - aka Freezing gait, people w parkinsons disease cannot move limbs.
GABA agonist, role in spasticity/HD - What drug is this?
Baclofen
What Anti-psychotic drug can cause a loss of Parkinson’s control?
Haloperidol - Anti-psychotic medication (blocks Dopamine Receptors - particularly D2 subtype responible for movement)
- can cause Drug induced PD
Why are dopamine agonists preferred under 70?
They cause less neurodegeneration than Levodopa and also have less chance of causing The “On-Off” effect.
