Psychiatric Drugs

Question 1

What are the main types of drugs that are used in treating Parkinson’s?

Answer 1

LevodopaDopamine receptor agonistsMAO Type B inhibitorsCOMT inhibitorsAnticholinergicsAmantadine

Question 2

Give some characteristics of Levodopa

Answer 2

Given with a peripheral dopamine antagonist, helps to reduce already large dosesVitamin B6 increases peripheral breakdown of L-DOPAAbsorbed in competition with amino acids90% inactivated by MAO and dopa decarboxylase in intestinal wall9% converted to dopamine in peripheral tissues1% crosses BBB

Question 3

Give some advantages of Levodopa

Answer 3

Very effectiveLow side effects

Question 4

Give some disadvantages of levodopa

Answer 4

Is a precursor, needs to be enzymatically converted. Loses efficacy over the long term - only works for about 2 years

Question 5

Give some examples of D2 receptor agonists

Answer 5

Bromocriptine - most used RopinirolePergolideApomorphine

Question 6

Give some characteristics of D2 agonists

Answer 6

Adjunct to L-DOPAADRs - nausea, hypotension, psychiatric symptoms

Question 7

Why do you use adjunct with L-DOPA?

Answer 7

Helps limit side effects and ADRs

Question 8

What is the MOA of monoamine oxidase type B inhibitors?

Answer 8

Selegiline selectively inhibits the MAOb enzyme which breaks down dopamine.

Question 9

Give some characteristics of COMT inhibitors

Answer 9

COMT degrades dopamine- causes increase in dopamine at substantia nigra

Question 10

Give some characteristics of anticholinergics

Answer 10

Antagonise muscarinic receptors that mediate striatal cholinergic excitation. Reduce excessive striatal cholinergic activity. ADRs - CNS (memory loss and acute confusional states)Need to withdraw gradually and parkinsonism can worsen if taken away abruptly

Question 11

Give some characteristics of amantidine

Answer 11

Stimulate neuronal dopamine release and inhibits dopamine re-uptake. Also has muscarinic antagonism actionADRs - anorexia, nausea, hallucinationsLoses effectiveness after 6 months

Question 12

Describe myasthenia gravis

Answer 12

Autoimmune destruction of end-plate ACh receptorsLoss of junctional folds at the end plate an the synaptic cleft widens

Question 13

Presenting symptoms of myasthenia gravis

Answer 13

Drooping eyelidsFatiguability and sudden falling (decreased ACh release)Double vision

Question 14

What are the treatments for myasthenia gravis?

Answer 14

Acetylcholinesterase inhibitorsCorticosteroidsPlasmapheresis

Question 15

Describe AChesterase inhibitors

Answer 15

PyridostigminePrevents ACh breakdown in synaptic cleftCan cause muscarinic effects

Question 16

Give some muscarinic effects

Answer 16

SSLUDGES- salivationS- sweatingL- lacrimationU- unrinary incontinenceD- diarrhoeaG- GI upset and hypermotilityE- emesis

Question 17

How do corticosteroids help in myasthenia gravis?

Answer 17

Decrease immune reponse

Question 18

How does plasmapheresis help in myasthenia gravis?

Answer 18

Removes the AchR antibodies, giving a short term improvement

Question 19

Give some drugs which can potentiate the effects of myasthenia gravis

Answer 19

AminiglycosidesBeta blockersChloroquinineSuccinylcholineMagnesiumACE inhibitors

Question 20

What is a myasthenic crisis?

Answer 20

An acute exacerbation of symptoms

Question 21

Give another acetylcholinesterase inhibitor which can be used

Answer 21

Neostigmine- can be given IV in ITU if no other option