1b Psychopharmacology for psychiatry

Question 1

targets for psychiatric medicines

Answer 1

receptors
neurotransmitter reuptake sites
ion channels
enzymes

Question 2

how are psychiatric drugs classified?

Answer 2

based on chemical structure
based on illnesses they treat
based on pharmacology

Question 3

pros/cons of grouping drugs based on chemical structure?

Answer 3

WHO classification system
pro - each drug has unique structure so easy to allocate data
con - no use in clinical decision making

Question 4

pros/cons of grouping drugs based on illnesses they treat?

Answer 4

pro - easy for Dr to choose drug as they make diagnosis
cons - many medicines work for several disorders, many psychiatric disorders have multiple symptoms, one drug may not treat them all
multiple symptoms may be based on different neurotransmitter systems

Question 5

how is grouping drugs based on pharmacology done?

Answer 5

neuroscience based nomenclature, targets neurotransmitters

Question 6

what is the only NT not taken back up by cell

Answer 6

Ach acetylcholine
acetylcholinesterase breaks it down

Question 7

what is a neuron auto-receptor?

Answer 7

usually inhibitory, activated by neurotransmitter it releases
inhibits calcium influx
switches off firing of terminal
reduces neurotransmitter release
(autoregulating neuron firing)

Question 8

what is the most common form of psychiatric drug? give an example

Answer 8

blocking enzyme activity
MOAIs for anxiety/depression block breakdown of serotonin and NA
acetylcholinesterase inhibitors for dementia
lithium blocking glycogen synthase kinase for mood stability

Question 9

give examples of receptor targeting psychiatric medicines

Answer 9

dopamine receptor blockers - schizophrenia
serotonin receptor subtype antagonists - depression
histamine receptor antagonists - sleep/insomnia
benzodiazapines - enhance GABA for sleep
guanfacine - enhance NA for ADHD

Question 10

how do reuptake targeting medicines produce effect?

Answer 10

most neurotransmitters are recycled via reuptake sites
drug blocks reuptake site
increases neurotransmitter concentration in synapse
enhances post-synaptic receptor activity
e.g citalopram SSRI

Question 11

reuptake targeting drugs examples

Answer 11

citalopram SSRI
desipramine - NA reuptake inhibitor (depression)
methylphenidate - dopamine reuptake inhibitor (ADHD)
amfetamine - ADHD swithces reuptake site direction to enhance release

Question 12

key neurotransmitter system in psychiatry and its receptors

Answer 12

5-HT
post synaptic 5-HT1A inhibitory, reduces downstream firing
5HT2A implicated in psychadelic drugs

Question 13

ion channel targeting psychiatric medicines examples (and channels targeted)

Answer 13

Na channels sodium valproate and carbamazepine - epilepsy and mood stabiliser
Ca channels - gabapentin, pregabalin - epilepsy and anxiety

Question 14

how are neurotransmitters categorised?

Answer 14

fast acting - on/off switches (effects on content e.g memory, movements)
slow acting - modulation - not on/off as too slow (effects on emotions/drives)

Question 15

examples of fast acting neurotransmitters

Answer 15

excitatory - glutamate from pyramidal cells
inhibitory - GABA from inter-neurons

Question 16

examples of slow acting neurotransmitters

Answer 16

only 5% of neurons
dopamine
serotonin
acetylcholine
noradrenaline
endorphins

Question 17

drug classes that treat depression

Answer 17

MAOIs
TCAs
SSRIs
SNRIs
receptor antagonists

Question 18

impact of excess glutamate in psychiatric disorders and its treatment

Answer 18

epilepsy - perampanel
alcoholism - acamprosate, ketamine

Question 19

impact of GABA deficiency in psychiatric disorders and its treatment

Answer 19

anxiety
treated by benzodiazapines (gaba enhancers)

Question 20

impact of 5-HT deficiency in psychiatric disorders

Answer 20

depression and anxiety
MAOIs and SRIs

Question 21

role of excess dopamine in psychiatric conditions and their management

Answer 21

psychosis

dopamine receptor blockers

Question 22

role of excess noradrenaline in psychiatric disorders and management?

Answer 22

nightmares
prazosin - blocker

Question 23

role of acetylcholine deficiency in psychiatric disorders and management?

Answer 23

impaired memory/dementia
acetylcholinesterase enzyme blockers

Question 24

what is a partial agonist?

Answer 24

lower max efficacy than full agonists
has improved safety - overdoses
can act as antagonist in states of high neurotransmitter
some intrinsic agonist to allow normal function

Question 25

examples of partial agonists?

Answer 25

aripiprazole
buprenorphine
varenicline

Question 26

what is an inverse agonist?

Answer 26

opposite effects to agonists
role of GABA in dementias and histamine in ADHD

Question 27

what is meant by GABA subtypes?

Answer 27

neurotransmitter has 14 subtypes
receptor made of 5 different proteins
different locations for different receptor subtypes meaning they have different functions

Question 28

comparison of dopamine blocker drug selectivity

Answer 28

haloperidol - very selective, adverse effects due to dopamine receptor block
clozapine - non selective, many adverse effects due to off targets (sedation, weight gain)

Question 29

what is allosteric modulation?

Answer 29

drug acts on different sites of same protein complex e.g benzodiazapines and alcohol (GABA)

Question 30

what is orthosteric binding?

Answer 30

drug binds to same site as endogenous neurotransmitter

Question 31

comparison of serotonin reuptake blocker drug selectivity?

Answer 31

amitriptyline - TCA, less selective. also inhibits histamine and acetylcholine receptor
citalopram - SSRI, adverse effects driven solely by inc serotonin