22) Drugs in Neurological Disorders Flashcards
What are the features of Parkinsonism?
Bradykinesia, rigidity, tremor
What signs and symptoms are those with Parkinson’s likely to develop?
Resting tremor Lead pipe and cog-wheeling rigidity Bradykinesia Postural instability Hypophonia
What are some other causes of Parkinsonism?
Drug induced - anti-psychotics Vascular Progressive supranuclear palsy Multiple systems atrophy Corticobasal degeneration
Describe the synthesis pathway for adrenaline:
L-tyrosine -> L-DOPA -> dopamine -> noradrenaline -> adrenaline
What is a DAT scan?
Using a labelled tracer, looks at the number of dopamine receptors in the brain
Why is L-DOPA used in treatment of Parkinson’s rather than dopamine?
Can cross the blood brain barrier
What can be given with L-DOPA to increase the amount reaching brain?
Carbidopa - peripheral DOPA decarboxylase inhibitor
What are the side effects of L-DOPA?
Nausea, hypotension, psychosis and tachycardia
What are the disadvantages of using L-DOPA long term?
Loss of efficacy (less cells to take up L-DOPA)
Involuntary movements
Motor complications
What are the disadvantages of dopamine receptor agonists?
Less efficacy than L-DOPA, impulse control disorders, psychiatric, expensive
Describe some impulse control disorders (caused by dopamine receptor agonists):
Pathological gambling
Hypersexuality
Compulsive shopping
Desire to increase dose
What are some side effects of dopamine receptor agonists?
Sedation, hallucinations, confusion, nausea, hypotension
Give an example of MAO type B inhibitor and its mechanism of action:
Rasagaline
Inhibits dopamine breakdown by enzyme which predominates in dopamine containing regions of the brain
Give an example of COMT inhibitor and its mechanism of action:
Entacapone
Reduces peripheral breakdown of L-DOPA to 3-O-methyldopa which competes with L-DOPA for AT across the BBB
Why may anti-cholinergics be used in treating Parkinson’s?
ACh can antagonise dopamine effects
Can treat tremor
