Psych - Pyschopharmacology: medicines in pyschiatry Flashcards
types of treatments in psych (4)
- chemical (+/- immunotherapy) e.g. drugs for depression
- Electrical stimulation
e. g. ECT for depression (neurostimu for pain syndromes) - Structural rearrangement
e. g. psychosurgery/deep brain stimulation for severe depression - Talking (psycho therapies)
e. g. CBT e.g. exposure for phobias
How to classify psychiatric drugs? (3)
- based on chemical structure (prodrug/active drug)
- -> not useful in clinical decision making - Based on the illnesses they treat
- -> problem as many meds work in several disorder e.g. antidepressants work for anxiety and OCD
- -> most psych disorders have multiple symptoms and a single medicine mighn’t treat them all. Likely have different NT mechanisms - Based on their pharmacology e.g. dopamine blocker, serotonin enhancer (GABA enhancer insteaf of hypnotic)
The 4 different sites that drugs act upon
- receptors
- NT reuptake sites
- Ion channels
- enzymes
enzymes of which organ can be particularly affected by psych drugs?
the liver
What is the only NT that isnt taken back up again?
ACh -> peptides broken down outside terminal
Examples of enzyme- targeting meds (3)
- MAOIs for anxiety/depression
- AChesterase inhibitors for dementia
- lithium
how does lithium help mood stability
- blocks glycogen synthase
Examples of receptor-blocker treatments (3)
- dopamineR blockers for schiz
- serotoninR subtype antagonists for depression (repuake?)
- histamineR antagonists for sleep
Examples of receptor-simulating treatments
- benzodiazeptines enhance GABA (Sleep)
2. guanfacine enhance NA (ADHD)
what does citalopram do?
enhances serotonin by inhibiting serotonin reuptake
-> for depression/anxiety
Give an example of a tricyclic antidepressant and what they do
Desipramine
Inhibitors of serotonin reuptake transporters (SERTs) and norepinephrine transporters (NETs)
This enhances noradrenaline and serotonin
Desipramine is a secondary TCA so only inhibits NETs and enhances noradrenaline
Give an example of a psychomotor stimulant drug
methylphenidate
enhances dopamine by inhibiting dopamine reuptake
Treatment for depression
what is an example of a drug that switches the reuptake site direction to enhance release?
- amfetamine for ADHD
- > lack of dopamine for reward centre in ADHD?
what type of receptor is the 5HT receptor?
an inhibitory receptor
-> increased stim of this receptors dampens activity of neurons where that receptor is
what conditions are thought to be related to the 5HT receptor?
- involved in conditions like schiz
- > also regulation of sleep and eating
drugs that block Na channels
sodium valporate
carbamazepine
-> both for epilepsy and mood stabilisation
drugs that block Ca channels?
gabapentin
pregabalin
-> both for epilepsy and anxiety
examples of fast acting NTs
- excitatory (glutamate) -> 80% of all neurons (pyramidal cells)
- inhibitory (GABA) -> 15%: interneurons
examples of slow acting NTs
- dopamin, serotonin, NA, ACh
- endorphins and other peptides
emotions, drives, valence of memory
what can XS glutamate cause?
epilepsy
alcoholism
treatment for XS glutamate? (3)
perampanel - blocker
acamprosate - blocker- helps with alcohol craving
ketamine - blocker
what can GABA deficiency cause?
anxiety
treatment for GABA deficiency
Benzodiazepines - GABA enhancer
what can 5-HT deficiency cause?
depression
anxiety
treatment for 5-HT deficiency
SSRIs and MAOIs - serotonin enhancer
what can XS dopamine cause?
psychosis
treatment for XS dopamine?
dopamine receptor blockers
what can XS NA cause?
nightmares
treatment for XS NA?
Prazosin - blocker
what can ACh deficiency cause?
impaired memory
dementia
treatment for ACh deficiency?
AChesterase enzyme blockers
benefits of partial agonists?
-> these have lower max efficacy than full agonists
- improved safety, esp in overdose
2. in states of high NT or excess agonist med, can act as an antagonist
examples of partial agonists
buprenorphine -safer than heroin
aripiprazole - safer than haloperidol (is used in the treatment of schizophrenia, tics in Tourette syndrome, mania in bipolar disorder, delirium, agitation, acute psychosis, and hallucinations in alcohol withdrawal.)
varenicline- safer than nicotine
how can you reverse amnestic effect of alcohol in humans?
give alpha51A inverse agonist
-> works in the hippocampus
what in an inverse agonist?
a drug that binds to the same receptor as an agonist but induces a pharmacological response opposite to that of the agonist
what is allosteric modulation?
a group of substances that bind to a different site on the receptor ( allosteric site) to enhance the effects of the neurotransmitter that binds to the orthosteric site of the receptor (normal binding site for the NT)
where does GABA binds to it’s receptor?
on the orthosteric site
-> the GABA-A receptor is an ion-channel linked
what happens when GABA binds to its receptor?
- enhances Cl- conductance -> inhibits neurons -> calms the brain
where do the benzodiazepines, barbiturates , alcohol and neurosteroids bind?
on the allosteric sites of the GABA-A receptor
- > enhance its action
- > leads to reduced anxiety, sleep, anti-epilepsy
