Anti-Parkinson Drugs Flashcards
what is Parkinson’s Disease?
chronic and progressive degenerate disease of the CNS that impairs motor skills and speech
what are symptoms of Parkinson’s Disease?
muscle rigidity
tremors
postural instability
bradykinesia/akinesia
mood disturbances
cognitive disturbances
sleep disturbances
what two areas of the brain are effected in Parkinson’s disease and what does this tell us?
Substantia nigra and Locus coeruleus have a loss of pigmentation which points to a loss of the neurotransmitters Dopamine and NE respectiively in those areas
what are risk factors of Parkinson’s Disease?
family history
male gender
head injury
exposure to pesticides
rural living
how is Parkinson’s disease diagnosed?
there are no blood or lab tests so diagnosis is based on medical history and neurological examination
what are the three major components of the motor system?
pyramidal
extra-pyramidal
cerebellum
explain the Pyramidal Tract and what a lesion would cause
responsible for voluntary movement,
starts in the motor cortex —> midbrain —> pons —> medulla —> spinal cord (LMN)
* lesion would cause muscle weakness or paralysis
**explain the Extra-Pyramidal Tract and what a lesion would cause
controls involuntary movement through the Basal ganglia and stratium and is a slow, indirect, multi-neuron path that connects to the motor and premotor areas
* lesion would cause tremors at rest, rigidity (PD)!!!!
explain the Cerebellar Pathways and what a lesion would cause
responsible for fine-tuning movement and balance and works through a feedback loop involving: Cerebellum → Red Nucleus → Thalamus → Motor Cortex
* lesion would cause intention tremor and ataxia
the deficit for Parkinson’s Disease lies in the
extra-pyramidal system that is composed of the basal ganglia and the striatum
the symptoms of Parkinson’s disease results from a loss of
dopamine-secreting (dopaminergic) cells in the pars compact of the substantia nigra
what is the pathway that is occurring in the brain that leads to Parkinson’s?
- substantia nigra is not releasing dopamine to activate the striatum (D1 receptors)
- an inactive striatum is not releasing GABA to inhibit GPi
- if GPi is active then it will inhibit the thalamus leading to hypokinesia
what is Sporadic/Idiopathic Parkinson’s?
Most common type with an unknown cause usually starting after the age of 40 where cells in pigmented brain areas (like the substantia nigra) die off
what is Genetic Parkinson’s?
Rare type that tends to appear in younger individuals caused by inherited mutations in certain genes (e.g., α-synuclein, parkin)
what is latrogenic Parkinson’s?
Drug-induced type from certain medications that interfere with dopamine usually occurring 3 months after starting the drug
what are examples of drugs that can cause latrogenic parkinson’s?
- Haloperidol, phenothiazines: Block dopamine receptors
- Reserpine, tetrabenazine: Deplete dopamine stores in the brain
what is Manganese Poisoning?
Manganese builds up in the substantia nigra, damaging cells that can mess with enzymes and causes oxidative stress to dopamine (DA)
what is Arteriosclerotic Parkinsonism?
strokes that cause damage to areas important for motor control (putamen), leading to Parkinson-like symptoms
what is Post-Encephalitic Parkinsonism (von Economo’s disease)?
A rare complication following viral encephalitis where people slowly develop Parkinson symptoms
what is MPTP-Induced Parkinsonism?
a toxic substance called MPTP causes damage to dopamine neurons by entering the brain and being converted by the enzyme MAO-B into MPP+ which kills dopamine-producing neurons in the substantia nigra
what is the current treatment for Parkinson’s disease?
symptomatic therapy that relies on a balance between:
- dopaminergic system (enhancing dopamine – D1 and D2 receptors) that has both excitatory and inhibitory effects
- cholinergic system (inhibit acetylcholine – specifically muscarinic receptors) that has mostly excitatory effects
what is L-DOPA (Levodopa)?
precursor to dopamine that can cross the BBB through neutral amino acid transporters and once inside the brain converts L-DOPA into dopamine
what are the side effects of L-DOPA?
most L-DOPA is converted to dopamine in the periphery (outside the brain) before it can enter the brain → causes side effects like nausea
what is Carbidopa?
drug that blocks the enzyme DOPA decarboxylase that converts L-DOPA into dopamine in the periphery (unable to cross BBB) which reduces nausea and increases the amount of L-DOPA that reaches the brain
* used in combo with L-DOPA
