antiparkisons and antipsychotics

Question 1

synthesis of dopamine

Answer 1

l-tyrosine converted into l-dopa then dopamine via tyrosine hydroxylase and DOPA decarboxylase respectively

Question 2

metabolism of dopamine+ locations of enzymes

Answer 2

taken up by dopamine or noradrenaline transporter, and broken down by MAO-A, MAO-B (more selective for dopamine) (either in presynaptic terminal or glial cell), or COMT (in post-synaptic membrane)

Question 3

main dopaminergic pathways and side effect of tubero pathway

Answer 3

nigrostriatal, mesolimbinc (reward), mesocortical (VTA to cerebrum), and TUBEROINFUNDIBULAR (arcuate nucleus to median eminence- inhibition= hyperprolactinaemia)

Question 4

cause of degeneration of nigrostriatal pathway

Answer 4

lewy bodies and neurites and present in neurones- may contribute

Question 5

non-motor symptoms of parkinsons

Answer 5

ansomia, constipation, hypotension, as well as memory loss

Question 6

main treatment of parkinsons and what given with and why

Answer 6

L-DOPA (levodopa), given with carbidopa (dopamine in periphery can lead to nausea), and COMT INHIBITORS (entacapone+tolcapone)

Question 7

side effects of levodopa and why

Answer 7

dyskinesia (opposite of bradykinesia if too much given) and ‘on-off’ effects (large dose of L-dopa given, which wears off quickly, leading to FLUCTUATIONS IN L-DOPA)

Question 8

other treatment for parkinsons

Answer 8

D2 receptor agonists- bromocriptine is an ERGOT derivative and may cause cardiac fibrosis, hence ROPINIROLE (non-ergot derivative) given

Question 9

treatment for parkinsons not often used

Answer 9

MAO B inhibitors eg Selegiline

Question 10

who most at risk for schizoprenia

Answer 10

between 15-35 yrs, highest in ethnic minorities

Question 11

symptoms of schizoprenia- binary

Answer 11

POSITIVE symptoms due to increased mesolimbic pathway- more hallucinations/delusions, can’t keep track on convos, and unpredictable: NEGATIVE symptoms due to decreased mesocortical pathway- lack of emotion, speech (allogia) and apathy (motivation)

Question 12

first generation anti-psychotics+ side effects: what type of symptoms does it treat

Answer 12

chlorpromazine and haloperidol- D2 receptor ANTAGONISTS: treats POSITIVE symptoms- lead to extrapyramidal symptoms ie parkisons like symptoms

Question 13

second generation antipsychotics+ side effects

Answer 13

CLOZAPINE- 5-HT receptor antagonists, which is the only drug to treat the NEGATIVE symptoms: can cause cardiac issues+ weight gain: RISPERIDONE- inhibit both 5HT and D2: ARIPRIPAZOLE is a PARTIAL agonist of both D2/5HT receptors