Psychopharmacology Flashcards

1
Q

What are the 4 main type of treatments in medicine?

A

Chemical
Electrical stimulation
Structural Rearrangement
Talking therapies

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2
Q

How can you class psychiatric drugs?

A

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.

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3
Q

What do medicines used in Psychiatry work on?

A

Receptors
Neurotransmitter Re-uptake sites
Ion channels
Enzymes

Targets are in the brain

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4
Q

What leads to some of the unwanted side effects of pharmacology?

A

Targets are in the brain but receptor may also be present outside the brain, leading to some of th unwanted side effects.

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5
Q

What are drug effects on ezyme activity?

A

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

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6
Q

What are the affects of receptor targeting medicines?

A

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

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7
Q

How do drugs affect re-uptake sites?

A

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

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8
Q

What are the most important post-synaptic serotonin receptors?

A

5HT1a

5HT2a

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9
Q

How do some drugs affect ion channels?

A

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

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10
Q

What are the 2 main types of neurotransmitters?

A
  1. 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.
  2. Slow acting (modulators) – about 5% of all neurons
    dopamine – serotonin – noradrenaline -acetylcholine
    endorphins and other peptides
    ->emotions, drives, valence of memory etc.
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11
Q

What are partial agonists?

A

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

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12
Q

What do inverse agonists do?

A

Opposite effects to agonists
GABA – pro-cognitive - ? dementias
Histamine – increased attention – ADHD
e.g. reverse alcohols amnestic effect in humans

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13
Q

How many subtypes are there of the serotonin receptor?

A

14

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14
Q

How do you get different receptor subtypes regulating different functions?

A

5 separate proteins make up a receptor - multiple different combinations

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15
Q

What happens in Allosteric Modulation?

A

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

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16
Q

How can you have different effects in dopamine blockers?

A

Haloperidol - Very selective for the dopamine receptor - Adverse effects due to dopamine receptor block.

Clozapine - Non-selective – lots of adverse effects due to off-target effects
E.g. sedation - weight gain – metabolic syndrome

Different side effects due to their other interactions as a product of different chemical structures.

17
Q

How can you have different effects in drugs blocking serotonin re-uptake?

A

Amitryptiline -One of the first antidepressants - “tricyclic” structure
- adverse effects from histamine and acetylcholine receptor blockade

Citalopram - A selective serotonin reuptake inhibitor(SSRI) – adverse effects driven solely by increased serotonin

Both drugs work by blocking serotonin reuptake – but have very different side-effect profiles due to their other interactions that are a product of their very different chemical structures