Treatment of PD

Question 1

Levodopa (1st choice)

Answer 1

Increase content of L-Dopa in basal ganglia

Usually combined with CARBIDOPA (Dopa decarboxylase inhibitor - peripheral action on gut - prevent severe vomiting side effects caused by excessive dopamine)

Initial improvement in rigidity and hypokinesia but limited effectiveness with time
Fluctuating clinical state due to receptor dynamics
Levodopa induced dyskinesia

Question 2

Dopamine agonists

Answer 2

(1) Ergots - Bromocriptine, Cabergoline, Pergolide
Action on D1/2 receptors

(2) Pramipaxole, Roprinole
Action on D2/3 receptors
used in younger patients as associated with cognitive function decline and hallucination in elderly

(3) Rotigotine
Transdermal patch

(4) Apomorphine
Injection or subcutaneous pump

Dopamine dysregulation syndrome:
Sudden onset of sleep, Neuroleptic malignant syndrome (Extreme rigidity, may lead to kidney failure) if withdraw abruptly, Impulse control disorder (Binge eating, hypersexuality gambling), Hypotension

Question 3

MAO -B inhibitor

Answer 3

Selegiline, Rasagiline

prevent extracellular breakdown of dopamine

Question 4

Amantidine

Answer 4

Antiviral drug (Uncoating inhibitor - prevent fusion with endosome - only works before infection, used in vulnerable contacts) as Dopamine release enhancer

Question 5

Ach Antagonist

Answer 5

BENZHEXOL; ORPHENADRINE; PROCYCLIDINE
Ach inhibitory effect on dopaminergic neurones, Antagonists compensate for lack of dopamine
Common cholinergic side effects - Dry mouth, Glaucoma