2. Antidepressants Flashcards
what are the 8 main classes of antidepressants?
- SSRI’s
- SNRI’s
- SARI’s (trazodone)
- TCA’S
- NDRI (bupropion)
- NaSSA (mirtazipine)
- MAOI
- multi-modal
NE’s action can be terminated through multiple mechanisms: dopamine can be transported out of the synaptic cleft and back into the presynaptic neutron via the ______________________ where it may be repackaged for future use
norepinephrine transporter
NE’s action can be terminated through multiple mechanisms: norepinephrine can be broken down extracellularly via the enzyme _____
COMT
NE’s action can be terminated through multiple mechanisms: these enzymes that can break down norepinephrine which are present in the mitochondria both with the presynaptic neutron and in other cells, including neurone glia
MAO-A and MAO-B
a presynaptic receptor on the norepinephrine neuron where NE binds and causes less production of NE?
alpha2 autoreceptor
what is the result if NE binds to and inhibits a postsynaptic alpa1 receptor
orthostasis
what is the result if NE binds to and activates a postsynaptic alpha2 receptor in the prefrontal cortex?
activation and insomnia
what is the result if NE binds to and activates a postsynaptic beta1 receptor in the prefrontal cortex?
mood regualtion; this is our target because beta1 is what is causing the issue in depression
if beta1 is activated in other parts of the body, may cause tremors and increased HR
what is the amino acid precursor for serotonin?
tryptophan
serotonins action is terminated by the enzymes _______ and ______ outside the neuron and ______ within the neuron when it is present in high concentrations
outside the neutron - MAO-A and MAO-B
inside the neutron - MAO-B
this clears serotonin out of the synapse and back into the presynaptic neuron
SERT
what are the 4 receptors that are present on the serotonin presynaptic neuron
5HT 1B/D autoreceptors brake
5HT 1A autoreceptors brake
alpha2 heteroreceptor brake
alpha1 heteroreceptor accelerator
what is the result when the 5HT 1a post-synaptic receptor is activated
mood regualtion and antidepressant efficacy therefore this is the target of drug action
what is the result when the 5HT 2a post-synaptic receptor is activated
5 A side effects
A - Agitation
A - Anxiety
A - Akathisia (restlessness)
A - Awake (insomnia)
A - Asexual (sexual dysfunction)
what is the result when the 5HT3 receptor is activated
headache and GI upset
(the migraine receptor)
what is the result when the 5HT 2C receptor is activated
weight gain
when an antidepressant is introduced, how quickly do neurotransmitter levels change, time to see a clinical effect and time for neurotransmitter receptors to be desensitized
- amount of NT changes rapidly
- time to see clinical effect and downregulation of neurotransmitter receptors is delayed
*known as the monoamine receptor down regulation hypothesis
true or false: when an antidepressant is introduced there is a lag time to see a clinical effect and side effects
false - lag time to see clinical effect but side effects can be seen right away but usually decrease overtime
true or false: upregualtion of postsynaptic monoamine neurotransmitter receptors results in depression
true
explain how antidepressants work with regards to the monoamine receptor hypothesis
monoamine receptor hypothesis: depression is caused by up regulation of monoamine receptors
when an antidepressant blocks a monoamine reuptake pump, this causes more NT to accumulate in the synapse.
the increased availability of NT causes the receptors to down regulate. the time for this to happen is consistent with the delayed clinical affects of antidepressants and the development of tolerance to antidepressant side effects
what are the 3 targets for drug action in the presynaptic/synaptic region by increasing the amount of NT available in the cleft
- block the reuptake pump
- block/cut the auto/heteroreceptor brakes
- inactivate the degrading enzymes
if this receptor is activated in the 5HT system, a patient may experience anxiety, akathisia, agitation, insomnia and/or sexual dysfunction
5HT2a
if this receptor is blocked in the 5HT system, a patient may experience headache and GI side effects
5HT3
if this receptor is blocked in the 5HT system, a patient may experience weight gain
5HT2c
if this receptor is blocked in the noradrenergic system, a patient may experience orthostasis
alpha 1
if this receptor is blocked in the histaminic system, a patient may experience sedation and weight gain
H1
if this receptor is blocked in the cholinergic system, a patient may experience dry mouth, dry eyes, blurry vision, constipation, urinary retention, confusion and delirium
M1
if this receptor is blocked in the cholinergic system, a patient may experience T2DM and impaired glucose tolerance (IGT)
M3
which TWO classes of antidepressants antagonize the serotonin reuptake pump as their main MOA?
1.selective serotonin reuptake inhibitors (SSRI’s)
- citalopram
- escitalopram
- fluoxetine
- fluvoxamine
- paroxetine
- sertraline
- serotonin antagonist reuptake inhibitors -> serotonin 2A antagonist/reuptake inhibitor
- trazodone
the serotonin reuptake inhibitor (SRI) portion of this drug molecule inserts into the serotonin reuptake pump, blocking it and causing an antidepressant effect
SSRI
SSRI’s can lead to increased 5-HT in the synapse which can then bind to a number of presynaptic receptors. what are these postsynaptic receptors and what effect will be seen if serotonin binds to them?
5HT1a - target receptor; causes downregulation of receptors and therefore treats the depression
5HT2a - “5A’s” - Agitation, Anxiety, Akathisia, Asexual, Awake
5HT3 - headache & GI upset
true or false: trazodone acts on both the presynaptic and post synaptic neuron
true
how does trazodone work on the presynaptic neuron?
the serotonin reuptake inhibitor (SRI) portion of trazodone is inserted into the serotonin reuptake pump and blocks it