Psychopharmacology Flashcards
What are the 4 main type of treatments in medicine?
Chemical
Electrical stimulation
Structural Rearrangement
Talking therapies
How can you class psychiatric drugs?
Based on chemical structure - but this dissent help in clinical decision making
Based on the illnesses that they treat - easy to choose drug, many psych drugs work in different disorders, most psych disorders have multiple symptoms - 1 might not treat them all.
Based on Pharmacology - classify drugs based on target they work on.
What do medicines used in Psychiatry work on?
Receptors
Neurotransmitter Re-uptake sites
Ion channels
Enzymes
Targets are in the brain
What leads to some of the unwanted side effects of pharmacology?
Targets are in the brain but receptor may also be present outside the brain, leading to some of th unwanted side effects.
What are drug effects on ezyme activity?
Almost always block enzyme activity e.g.
E.g. monoamine oxidase inhibitors [MAOIs] for anxiety and depression
E.g. acetylcholinesterase inhibitors for dementias
E.g. lithium blocks glycogen synthase kinase for mood stability
What are the affects of receptor targeting medicines?
Most treatments are receptor blockers [antagonists]
E.g. dopamine receptor blockers for schizophrenia
E.g. serotonin receptor subtype antagonists for depression
E.g. histamine receptor antagonists for sleep
Some stimulate receptors = enhancers (agonists)
E.g. benzodiazepines enhance GABA sleep
E.g. guanfacine enhance noradrenaline ADHD
How do drugs affect re-uptake 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
Some switch the reuptake site direction to enhance release
e.g. amfetamine for ADHD
What are the most important post-synaptic serotonin receptors?
5HT1a
5HT2a
How do some drugs affect ion channels?
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 2 main types of neurotransmitters?
- FAST acting (on-off switch)
Excitatory – glutamate = > 80% of all neurons - pyramidal cells
Inhibitory – GABA = 15% - inter-neurons
-> content e.g. of memory, movement, vision etc. - Slow acting (modulators) – about 5% of all neurons
dopamine – serotonin – noradrenaline -acetylcholine
endorphins and other peptides
->emotions, drives, valence of memory etc.
What are partial agonists?
Partial agonists – lower max efficacy than full agonists
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 do inverse agonists do?
Opposite effects to agonists
GABA – pro-cognitive - ? dementias
Histamine – increased attention – ADHD
e.g. reverse alcohols amnestic effect in humans
How many subtypes are there of the serotonin receptor?
14
How do you get different receptor subtypes regulating different functions?
5 separate proteins make up a receptor - multiple different combinations
What happens in Allosteric Modulation?
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
