Parkinsons Disease Flashcards
Why is levodopa used instead of dopamine to treat Parkinson’s disease?
Dopamine cannot cross the blood-brain barrier (BBB), so it cannot reach the brain to replenish dopamine levels.
Levodopa is a precursor to dopamine that can cross the BBB and be converted into dopamine in the brain.
To reduce peripheral side effects (e.g., nausea, vomiting), levodopa is combined with carbidopa, a DOPA decarboxylase inhibitor that prevents peripheral conversion of levodopa to dopamine.
How is Parkinson’s disease classified?
A neurodegenerative disorder caused by the progressive loss of dopaminergic neurons in the substantia nigra pars compacta, leading to motor and non-motor symptoms.
What are the core motor symptoms of Parkinson’s disease?
Bradykinesia – slowness of movement
Rigidity – resistance to passive limb movement
Resting tremor – occurs when limbs are at rest
Postural instability – impaired balance, leading to falls
What are some non-motor symptoms of Parkinson’s disease?
Depression, cognitive impairment, sleep disturbances, autonomic dysfunction (e.g., constipation, orthostatic hypotension).
How is Parkinson’s disease diagnosed?
Clinical diagnosis based on motor symptoms, with supportive criteria such as response to levodopa. No definitive lab test.
What imaging tests may help in uncertain cases?
DaTscan (dopamine transporter scan) – Shows reduced dopamine activity in the substantia nigra.
MRI/CT scan – Used to rule out other conditions (e.g., stroke, tumors).
What is the first-line treatment for Parkinson’s disease?
If motor symptoms affect quality of life → Levodopa + carbidopa (co-careldopa) or benserazide (co-beneldopa)
If motor symptoms do not affect quality of life → Choice of:
Levodopa
Non-ergot dopamine agonists (pramipexole, ropinirole, rotigotine)
MAO-B inhibitors (rasagiline, selegiline)Levodopa + Carbidopa (e.g., Sinemet) or Levodopa + Benserazide (e.g., Madopar)
Most effective for improving bradykinesia and rigidity, but long-term use can lead to motor complications.
non-drug treatments are available for Parkinson’s disease?
Physiotherapy for balance/motor issues
Speech therapy for communication/swallowing problems
Occupational therapy for daily activities
Dietitian referral if needed
What are treatment options for advanced Parkinson’s disease?
Apomorphine (subcutaneous injection or continuous infusion)
Domperidone (for nausea, ECG monitoring required)
Deep Brain Stimulation (if symptoms are uncontrolled on medication)
Intestinal levodopa gel or subcutaneous foslevodopa/foscarbidopa infusion (if apomorphine & DBS fail)
hat impulse control disorders can occur in Parkinson’s?
Compulsive behaviors: Gambling, hypersexuality, binge eating, shopping
More common with: Dopamine agonists
Management:
Reduce or stop dopamine agonists gradually
Monitor for withdrawal symptoms
Consider cognitive behavioral therapy (CBT)
second-line treatment options for Parkinson’s disease?
Dopamine agonists (e.g., pramipexole, ropinirole, bromocriptine) – Used in younger patients to delay levodopa use.
MAO-B inhibitors (e.g., selegiline, rasagiline) – Reduce dopamine breakdown.
COMT inhibitors (e.g., entacapone, tolcapone) – Extend the effect of levodopa.
Amantadine – Helps with dyskinesias (levodopa-induced involuntary movements).
adverse effects of levodopa?
Nausea, vomiting (due to peripheral dopamine activation)
Dyskinesias (involuntary movements, common with long-term use)
“On-Off” phenomenon (fluctuations in symptom control)
Postural hypotension
