Psychopharmacology for psychiatry Flashcards
What 4 types of treatments are there in medicine (with psych examples)
Chemical: drugs/medicines (antidepressants, antipsychotics, anxiolytics)
Electrical stimulation: ECT for depression, neurostimulation for pain syndromes
Structural rearrangement: surgery and orthopaedics (psychosurgery/ deep brain stimulation for severe depression )
Talk therapy: CBT, exposure therapy for anxiety
What 3 methods can we use for drug classification?
Based on chemical structure
Based on the illness they treat
Neuroscience based nomenclature
Pros and cons of classifying drugs based on chemical structure
Pro: every single drug has a unique structure, so there’s specific identification and easy allocation of data
Con: no use in clinical decision making
Pros and cons of classifying drugs based on the illness they treat
Pro: easy for Drs to choose a drug as docs make diagnosis (e.g. antidepressants, anti-psychotics, anxiolytics, hypnotics)
Cons: Certain drugs treat many different mental conditions (e.g. antidepressants can be used to treat depression but also anxiety and OCD)
Mental conditions have many different symptoms, all of which cannot be treated by a single drug (e.g. depression is characterised by anhedonia, anergia, low mood, poor concentration, loss of appetite, loss of libido)
How does neuroscience based nomenclature work?
We classify drugs based on the neurotransmitter they target (e.g. instead of antidepressants, we say serotonin enhancers)
What are the 4 main drug targets?
Transport proteins
Ion channels
Receptors
Enzymes
((TIRE))
How do drugs that target receptors work?
Most of these are antagonists (blockers)
e.g. dopamine receptor antagonists for psychosis, serotonin receptor subtype antagonists for depression, histamine receptor antagonists for sleep
Some enhance receptor activity
e.g. benzodiazepines enhance GABA for sleep
guanfacine enhances noradrenaline for ADHD
How do drugs that target ion channels work?
Some drugs block ion channels and reduce neuronal excitability
Sodium channel blockers (e.g. carbamazepine, sodium valproate) for epilepsy and mood stabilisation
Calcium channel blockers (e.g. gabapentin, pregabalin) for epilepsy and anxiety
How do drugs that target enzymes work?
Generally block enzyme activity
e.g.
Monoamine oxidase inhibitors for anxiety and depression (prevent breakdown of serotonin)
Acetylcholinesterase inhibitors for dementia (Block ACh breakdown)
lithium blocks glycogen synthase kinase for mood stability (stabilises neurones)
How do drugs targeting reuptake sites function?
Many block re-uptake sites to increase neurotransmitter concentration in the synapse and enhance post synaptic receptor activity
Serotonin re-uptake transporters (citalopram): depression and anxiety
Dopamine reuptake inhibitors (methylphenidate): ADHD
Noradrenaline re-uptake inhibitors (desipramine): depression
Some drugs switch re-uptake site direction to enhance release
Amphetamines for ADHD
How does the 5-HT system stop itself from releasing too much 5-HT?
Serotonin released acts on presynaptic auto receptors to inhibit further NT release through negative feedback
How many post synaptic serotonin receptors are there in the brain?
14
What are the 2 main types of post synaptic serotonin receptor?
5-HT1A: inhibitory receptor which dampens activity in neurones to reduce depression and anxiety
5-HT2: psychedelic drugs act on this to produce hallucinogenic effects. May be involved in schizophrenia and is involved in eating and regulation of sleep
How can the effects of neurotransmitters be divided into 2 groups?
Fast acting
Slow acting
How can the effects of neurotransmitters be divided into 2 groups?
Fast acting
Slow acting
What is the function of fast acting neurotransmitters?
On-off switch
What is the function of slow acting neurotransmitters?
Modulators
Give 2 examples for fast acting neurotransmitters
Glutamate (major excitatory neurotransmitter)
GABA (major inhibitory neurostransmitter)
What type of neurones secrete glutamate and what percentage of all neurones do these make up?
Pyramidal cells
=>80%
What type of neurones secrete GABA and what percentage of all neurones do these make up?
Interneurons
15%
What is the balance of GABA and glutamate responsible for?
Contents of everything we do
e.g. memory, movement, vision
Give examples for slow acting neurotransmitters
Dopamine, serotonin, noradrenaline, enkephalins, endorphins and other peptides