1b// Pharmacology of Psychiatry Flashcards
What are the types of treatments in medicine?
Chemical – drugs/medicines (+Immunotherapy)
e.g. drugs for psychosis e.g. drugs for depression
Electrical stimulation
e.g. ECT for depression e.g. neurostimulation for pain syndromes
Structural rearrangement - surgery & orthopaedics
e.g. psychosurgery/deep brain stimulation for severe depression
Talking (pycho) therapies
e.g Cognitive Behaviour Therapy (CBT) e.g. exposure for phobias
What are the options on how to classify psychiatric drugs?
- based on chemical structure
- based on what illnesses they treat
- based on their pharmacology
What are the pro and cons of classifying drugs based on their chemical structure?
E.g. as the WHO classification system does
Pro- each drug has a unique structure = a fact so easy to allocate data
Con – no use in clinical decision making
What are the pros and cons of classifying drugs based on what illnesses they treat?
E.g. antidepressant - antipsychotic – anxiolytic – hypnotic
Pros – easy for Drs to choose a drug as docs make diagnosis
Con –1. many psychiatric medicines work in several disorders
E.g. - antidepressants also treat anxiety and OCD (obsessive compulsive disorder)
E.g. – some antipsychotics used as add on (augmentation) treatment for depression
Con- 2. most psychiatric disorders have multiple symptoms and a single medicine might not treat them all
E.g. symptoms in depression include – anxiety-insomnia-low mood-agitation-loss of pleasure- loss of appetite- poor concentration -loss of libido with likely different neurotransmitter mechanisms
What does it mean to classify drugs based on their pharmacology?
Core pharmacology used to classify medicines
Targets neurotransmitters
E.g. instead of antipsychotic – we can say dopamine blocker
E.g. instead of antidepressant – we can say serotonin (or with some drugs noradrenaline or dopamine enhancer)
E.g. instead of hypnotic or anxiolytic – we can say GABA enhancer
What are the types of GABA receptors?
GABA-A
GABA-B
What does NbN stand for?
neuroscience based on nomenclature
What is the benefit of NbN?
makes it clear e.g., Alprazolam -GABA-A PAM
What is an example of a GABA-B agonist?
baclofen
What do drugs work on?
receptors
neurotransmitter reuptake sites
ion channels
enzymes
*TARGETS ARE IN THE BRAIN
BUT CAN AFFECT SYSTEMS ELSEWHERE IN BODY ESPECIALLY LIVER ENZYMES
Describe the basic neuronal principles.
What do MAOIs do?
monoamine oxidase inhibitors [MAOIs] for anxiety and depression
work on enzyme activity
What do acetylcholinesterase inhibitors treat?
dementias
work on enzyme activity
What does lithium do?
lithium blocks glycogen synthase kinase for mood stability
work on enzyme activity
What are receptor blockers called?
antagonists
What are receptor enhancers called?
agonists
aka stimulate receptors
Give examples of antagonists?
E.g. dopamine receptor blockers for schizophrenia
E.g. serotonin receptor subtype antagonists for depression
E.g. histamine receptor antagonists for sleep
Give examples of agonists?
E.g. benzodiazepines enhance GABA=> sleep
E.g. guanfacine enhance noradrenaline => ADHD
Give examples of drugs that block neurotransmitter block reuptake sites?
Many psychiatric drugs block these reuptake sites so increase neurotransmitter concentration in the synapse to enhance post-synaptic receptor activity
e.g. citalopram – enhances serotonin (= serotonin reuptake inhibitor or SRI)– for depression and anxiety
e.g. desipramine – noradrenaline reuptake inhibitor (NRI)= enhances noradrenaline - for depression
e.g. methylphenidate – dopamine reuptake inhibitor (DRI)- enhances dopamine - for ADHD
Give drugs that enhance release sites of neurotransmitters?
e.g. amfetamine for ADHD
they switch the reuptake site direction to enhance release
Describe the 5-HT neurotransmitter system.
Give examples of ion targeting medicines.
Some drugs block channels so reduce neuronal excitability
Sodium channels
E.g. sodium valproate- epilepsy and mood stabilisation
E.g. carbamazepine - epilepsy and mood stabilisation
Calcium channels
E.g. gabapentin & pregabalin – epilepsy anxiety
What are the fast acting neurotransmitters?
Excitatory – glutamate = > 80% of all neurons - pyramidal cells
Inhibitory – GABA = 15% - inter-neurons
=> content e.g. of memory, movement, vision etc.
What are the slow acting neurotransmitters?
Slow acting (modulators) – about 5% of all neurons
dopamine – serotonin – noradrenaline -acetylcholine
endorphins and other peptides
=> emotions, drives, valence of memory etc.
What are the neurotransmitter system in psychiatric disorders? (6)
What are the drugs that treat depression and give examples? (8)
What are partial agonists?
Partial agonists – lower max efficacy than full agonists
Partial agonists aredrugs that bind to and activate a given receptor, but have only partial efficacy at the receptor relative to a full agonist
What do partial agonists do?
Improved safety – especially in overdose
In states of high neurotransmitter or excess agonist medicine can act as an antagonist
E.g. buprenorphine < heroin
E.g. aripiprazole < haloperidol
E.g. varenicline < nicotine
What are inverse agonists?
opposite effects to agonists
Inverse agonistbinds to the samereceptor as agonist but induces a pharmacological response opposite to that of the agonist
Give an example of a receptor subtype.
GABA-A receptors
What are the 2 sites that neurotransmitters and drugs can act on?
orthosteric site
allosteric site
What is the difference between orthosteric site and allosteric site?
Some drugs act on the same site as the natural (endogenous) neurotransmitter
Others work on different sites on the target proteins
E.g.
GABA-A receptor is an ion-channel linked receptor
GABA binds to the GABA receptor = orthosteric site
This binding enhance chloride ion conductance
=> inhibits neurons => calm the brain
Benzodiazepines – barbiturates –alcohol – neurosteroids
All act at allosteric sites on the same protein complex
They enhance the action of GABA => sedation, sleep, reduce anxiety, anti-epilepsy
Compare the 2 dopamine receptor blockers drugs for schizophrenia.
haloperidol
clozapine
Compare 2 5-HT reuptake blockers.
amitriptyline
citalopram
for depresion
What is allosteric modulation?
Y/N
Y/N
Y/N
Y/N
