Parkinson's Flashcards
Signs and symptoms
Shuffling gait Stooped posture Monotonic speech Masked face Freezing, struggles to start/stop moving
Compensations by rewiring can help up to
80% neurones in movement pathway lost
Dopamine pathways (5)
Motor function Reward Psychosis Prolactin secretion Nausea/vomiting
Enzyme that metabolises dopamine
COMT, polymorphisms determine how much dopamine is active, links to risk behaviour
Carbidopa, benserazide use
Used for pheochromocytoma and as adjunct with L-DOPA so L-DOPA is used in CNS
Carbidopa, benserazide MOA
Inhibits DOPA decarboxylase, prevents L-DOPA -> dopamine, doesn’t cross BBB so only in body hence used as adjunct to L-DOPA
D2R antagonist MOA
Domperidone blocks D2 receptors in periphery, reduces SE from dopaminergic drugs
D2R antagonist use
Mainly anti-emetic, used as adjunct to L-DOPA/D2 agonist to prevent SE from dopamine
Muscarinic antagonist MOA
Procyclidine, orphenadrine, benzhexol block muscarinic receptors in striatum
Muscarinic antagonist use
Only used in drug-induced PD (DA antagonists used in antipsychotics) as increases susceptibility to dementia in elderly patients
Muscarinic antagonist SE
Dry mouth, urinary retention, constipation
MAO-B inhibitors MOA
Selegiline, rasagiline inhibit dopamine specific breakdown enzyme in brain, potentiates L-DOPA
MAO-B inhibitor use
Adjunct to L-DOPA as can reduce dose needed by up to 1/3, also has anti-parkinsonian action when used alone and delays need for Levodopa
D2 agonist MOA
Ropinirole (monotherapy in younger), Bromocriptine, pergolide act on D2 receptors
D2 agonist SE
Restrictive valvular heart disease
Nausea
Psychiatric symptoms
Postural hypotension
Behaviour changes (gambling/hypersexuality)
Daytime somnolence (strong desire for sleep)
D2 agonist use
Used with domperidone to prevent nausea, used mostly in young patients or in late disease to buffer L-DOPA fluctuation but usually apomorphine for this instead
Amantidine MOA
Initially made as antiviral but blocks NMDA receptors and works well for small % of patients without SE
Possibly works due to effect on glutamate in globus pallidus and thalamus
Deep brain stimulation use
STN stimulation works well in some who haven’t responded to other treatments, very expensive so used last ditch
Other motor problems and treatments
Huntingdons Chorea - tetrabenazine depletes DA
Restless legs - ropinirole (possibly decreases DA sensitivity)
Tourettes - haloperidol (DA antagonist), pimozide
