Pharmacology of the Basal Ganglia disorders Flashcards
What is dystonia?
Lasting muscle spasms; repeated twisting movements or altered posture.
Occurs in Parkinson’s
If a patient has writhing movements, what is it called?
Athetosis
Occurs in Huntington’s
If a patient has twitching or jerking of a group of muscles, what do they have?
Chorea
Occurs in Huntington’s
And too much Levodopa - e.g. Parkinson’s patient on too high a dose
What is Ballismus?
Large, flinging, limb movements (Hemiballismus - unilateral)
Caused by any damage to subthalamic nuclei
What regions of the brain are involved in Parkinson’s, Huntington’s and Hemiballismus?
Parkinson’s - Substantia nigra (loss of dopamine)
Huntington’s - Striatum (Caudate and Putamen - loss of GABA cells and ACh)
Hemiballismus - Subthalamic nuclei
What is Wilson’s disease?
Pseudoparkinsonism - due to toxic copper buildup.
What type of parkinsonism is Progressive Supranuclear Palsy disease?
Parkinsonism with extras
Name the 4 main DOPAMINE pathways
Nigrostriatal/Mesostriatal (SN to Striatum)
Mesolimbic (ventral tegmental area in the midbrain, to the ventral striatum of the basal ganglia)
Mesocortical (connects the ventral tegmentum to the prefrontal cortex)
Tubero-hypophyseal (hypothalamus to pituitary gland - dopamine antagonist means more prolactin produced)
What are the three main groups that Parkinsonism can be divided into and name some examples of each?
Pure Parkinsonism:
Idiopathic – Parkinson’s disease
Iatrogenic
Post-encephalitic
Parkinsonism with extras:
Multiple systems atrophy (3-types: MSA-A*, -P, -C)
Progressive supranuclear palsy
Pseudoparkinsonism:
Wilson’s disease
Essential Tremor
Trauma and vascular-related
What are the four cardinal features of parkinsons (TRAP)?
Tremor (resting)
Rigidity (lead pipe, cogwheel)
Akinesia (bradykinesia)
Postural instability
What are the three main pharmacological treatments for Parkinsonism?
Levodopa Dopamine agonists (if motor not affection QOL) MAOB inhibitor (if motor not affection QOL)
Why can you not use dopamine for treatment of parkinsonism?
Dopamine does not cross the blood brain barrier. Therefore you use the precursor (Levadopa)
What is the name of the enzyme which converts L-Dopa to Dopamine?
Dopa-decarboxylase
What do you have to give a patient with parkinsonism, along with Levadopa?
DDIs (Dopa-decarboxylase inhibitors):
Carbidopa
Benserazide
Combined with L-Dopa:
Co-careldopa
Co-beneldopa
How will giving a dopmaine antagonist to a patient, affect lactation?
One of the main regulators of the production of prolactin from the pituitary gland is the hormone called dopamine, which is produced by the hypothalamus. Dopamine restrains prolactin production, so the more dopamine there is, the less prolactin is released. Therefore, a dopamine antagonist will increase the levels of prolactic and so activate lactation.
What can you give to prevent breakdown of Dopamine?
Monoamineoxidase inhibitors (MAOB)
Use alone in early stage or as adjuvant with L-dopa:
Selegiline
Rasagiline
Catechol-O-methyltransferase (COMT) inhibitors
At later stages if L-Dopa and MAOB insufficient can include as an adjunct:Entacapone
Tolcapone
Name some dopamine synthetic agonists.
Pramipexole - most important!
Ropinirole
Rotigotine