Antidepressants Flashcards

1
Q

What are some common SSRI

A

Fluoxetine
Paroxetine
Sertraline
Citalopram

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2
Q

What is the mechanism of SSRI

A

Binds to Serotonin transporter (SERT) → Inhibition of serotonin reuptake in synaptic clefts → increased serotonin levels in synaptic space

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3
Q

Name 4 important side effects of SSRIs

A
  1. Most important: Serotonin Syndrome
  2. Nausea
  3. insomnia
  4. sexual dysfunction
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4
Q

What is serotonin syndrome?

A

Serotonergic overactivity due to the use of serotonin drugs either due to therapeutic dose or overdose of serotonergic drug, use of multiple serotonergic drugs, or interactions with CYP-450 inhibitors

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5
Q

Symptoms of Serotonin syndrome

A
  1. Hyperthermia
  2. Tremor
  3. Sexual dysfunction
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6
Q

How to treat sexual dysfunction from SS

A

Cyproheptadine or other 5-HT2 blockers can be given to reduce the effects caused by the excessive serotonin in synaptic cleft

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7
Q

Why is SSRI better than TCA

A
  1. Greater 5-HT reuptake selectivity than TCAs (Fluoxetine 50x more selective
    Citalopram 1000x more selective)
  2. Fewer adverse effects than TCA
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8
Q

What is a common NARI

A

Ruboxetine

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9
Q

Why is NARI very commonly used?

A
  1. Greater NA reuptake selectivity than TCAs. (Approximately 1000-fold selectivity for NA over 5-HT)
  2. Fewer adverse effects than TCAs and SSRIs
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10
Q

Adverse effects of ruboxetine (NARI)

A
  1. Anticholinergic side effects (Dry mouth, Constipation)
  2. Insomnia (Increased NA activities in CNS)
  3. Tachycardia (Increased NA activities → sympathetic activation in CVS)
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11
Q

What are SNRIs?

A

Serotonin and Noradrenaline reuptake Inhibitors (SNRIs)

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12
Q

What are some commonly used SNRIs?

A
  1. Venlafaxine
  2. Desvenlafaxine (synthetic metabolite of venlafaxine)
  3. Duloxetine
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13
Q

What is the mechanism of SNRIs?

A

Inhibition of serotonin and norepinephrine reuptake in synaptic cleft → ↑ serotonin and norepinephrine levels

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14
Q

Side effects of SNRIs

A

Similar to SSRIs

  1. Nausea
  2. Insomnia
  3. Sexual dysfunction
  4. Serotonin syndrome when combined with other serotoninergic drugs and MAOIs
  5. Withdrawal effects may be stronger compared to SSRIs or TCAs
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15
Q

Name some other antidepressants (atypical antidepressants)

A
  1. Mirtazapine
  2. Bupropion
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16
Q

Mechanism of Mirtazapine

A

α2, H1, 5-HT2, and 5-HT3 receptor antagonists → ↑ serotonin and norepinephrine release and ↑ effect of serotonin on free 5-HT1 receptors

17
Q

What are Monoamine oxidases?

A

Breaks down monoamines

18
Q

Major forms of monoamine oxidases

A

Two major forms,MAO-A and MAO-B:
1. 5-HT broken down mainly by MAO-A.
2. Both forms act on noradrenaline (NA) and dopamine.

19
Q

Name some common MAOIs

A
  1. Phenelzine (non-selective)
  2. Selegiline (selective for Mao-B)
20
Q

Mechanism of Phenelzine

A

Non-selective, irreversible inhibition of monoamine oxidase → reduce breakdown of epinephrine, NE, serotonin, dopamine

21
Q

Mechanism of Selegiline

A

Selective Mao-B inhibitor → mainly decrease breakdown of dopamine → increase dopamine levels

22
Q

What other condition is seligiline used for and why?

A

Parkinson’s disease (lack of dopamine in the basal ganglia resulting in motor dysfunctions)
Inhibits Mao-B, increase dopamine levels in the basal ganglia, reduce Parkinson’s symptoms

23
Q

Adverse effects of MAO-Is

A
  1. Postural Hypotension
  2. Restlessness and insomnia
  3. Hyperexcitability, increased muscular tone, myoclonus (jerking, involuntary movements), loss of consciousness when taken with other serotonergic drugs
24
Q

Why are MAO-Is discontinued?

A

Irreversible inhibition of MAOs and hence lead to excessive monoamines (NE, dopamine, 5HT) in the synaptic cleft, constant stimulation of the CNS leading to

Risk of Hypertensive crisis
Postural hypotension
insomnia and agitation

Often prescribed at Sub therapeutic levels due to these pronounced side effects hence either too much or too little (shagggggg)

25
Q

What are TCAs

A

First generation monoamine reuptake inhibitor antidepressants

26
Q

What are some common TCAs?

A

Non-selective for SERT/NET
1. Imipramine
2. Amitryptiline
3. Nortriptyline (2nd gen, milder side effects)

Selective for NET
1. Desipramine

27
Q

Mechanism of TCAs

A

Inhibition of serotonin and norepinephrine reuptake in synaptic cleft → ↑ serotonin and norepinephrine levels

28
Q

Adverse effects of TCAs

A

MNEMONIC OF TCA

  1. Tremors
  2. Cardiovascular adverse effects (Postural hypotension)
  3. Anticholinergic side effects (Dry mouth, blurred vision, constipation due to muscarinic receptors antagonism)
29
Q

What is the necessary thing to do before administering TCAs?

A

Test for plasma albumin levels
TCAs are plasma protein bound and low albumin levels will increase availability and hence concentration in bloodstream

30
Q

How are TCAs metabolised

A

Hepatic metabolism and elimination