CPTP 3.3 Neuropharmacology 1 (Antidepressants) Flashcards
(42 cards)
What creates biological vulnerabilities for depression and mood disorders?
- Genetic predisposition
* Early adverse life experiences
Are catecholamines monoamines?
Yes
list the catecholamines
- NA
- Serotonin
- Dopamine
Outline briefly the monoamine hypothesis?
Depression is due to a deficit in central monoamine neurotransmission.
What evidence is there against monoamine theory?
- Cocaine inhibits NA uptake, but isn’s an antidepressant
* Lowered monoamines aren’t seen in patients with depression
Outline the biochemical pathway for the synthesis of 5-HT
Tryptophan –TPH–> 5-HTP
5-HTP –AADC–> 5-HT
TPH = tyrptophan hydroxylase AADC = 5-hydroxytryptophan decarboxylase
What occurs to 5-HT after synthesis?
Either stored into vesicles or broken down by MAO into 5-HIAA and extruded
What are the most important postsynaptic 5-HT receptors?
- 5-HT 1A
- 5-HT 1B
- 5-HT 2A
- 5-HT 2C
What is the 5-HT autoreceptor?
5-HT 1A
How is serotonin terminated?
SERT in the presynaptic membrane pumps 5-HT back into the presynaptic neurone.
It can then either be transported back into vesicles or broken down by MAO
What two pharmacological targets are there for antidepressants?
The termination step:
• MAO
• SERT
Which antidepressants block 5-HT reuptake?
- Tricyclic antidepressants
- SSRIs
- SNRIs (serotonin & noradrenaline)
Which antidepressants block NA reuptake?
- SNRIs (serotonin & noradrenaline)
* NARIs
What effect do reuptake inhibitors have?
They prolong the effects of the neurotransmitter
What are the clinical limitations of TCAs?
- Delayed onset of 2 weeks before effective
- M1 antagonistic effects
- H1 antagonistic effects
- a1-adrenoreceptor antagonistic effects
- Cardiotoxic in overdose
What do TCA M1 antagonistic side effects include?
- dry mouth
- blurred vision
- constipation
- urinary retention
What do TCA H1 antagonistic side effects include?
- Sedation
* Weight gain
What do TCA a1 antagonistic side effects include?
Postural hypotension
What do the clinical limitations of TCAs result in?
Feeling worse before you feel better because the side effects are immediate but the therapeutic effects are delayed
This results in poor compliance
What are the benefits of TCAs
- Can be used for severe or resistant (other drugs aren’t working) depression
- They are cheap
In what groups are TCAs not used?
- Elderly
- Young
- Cardiac patients
- Suicidal patients (overdose)
- Drivers (sedation)
Why are TCAs not used in cardiac patients?
They increase the chance of conduction abnormalities.
What are the ‘second generation’ antidepressant classes? What is special about these?
• SSRIs
• SNRIs
• NARI
Selective for 5-HT or NA transporters and do not have affinity for postsynaptic receptors so there are fewer side-effects
How do SSRI and SNRI efficacies compare to those of TCAs?
The same (but far fewer side-effects) “Clean drugs”, high selectivity