Antidepressants Flashcards

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1
Q

What monoamines are metabolized by Mao-A vs Mao-B

A

MAO-A: NE, Epi, Serotonin, Dopamine, tryamine

MAO-B: trace amines, DOPAMINE, 5HT at high concentrations, tyramine

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2
Q

Which irreversible MAO-I binds preferentially to MAO-B?

A

Selegiline

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3
Q

What are some common side effects of MAO inhibitors?

A
GI-nausea, constipation, appetite change, 
Orthostatic hypotension-dizziness
Sedation
Sleep disturbances
Sexual dysfunction
Weight gain
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4
Q

Name two irreversible MAO inhibitors

A

Phenelzine and Tranylcyrpromine

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5
Q

What are two serious adverse effects associated with MAO-I’s

A

Hypertensive crisis

Serotonin syndrome

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6
Q

Which MAO-I has the lowest risk of a hypertensive crisis?

A

selegeline: it preferentially inhibits MAO-B.
MAO-A is responsible for metabolism of tyramine by the GI tract

Tyramine is a pressor –> release of NE –> hypertensive crisis

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7
Q

What are the symptoms of serotonin syndrome?

A

Hyperreflexia
Myoclonus
Autonomic dysfunction (increased bp, increased temp)
Disorientation

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8
Q

How do secondary TCA’s work?

A

NE > 5HT re-uptake inhibitor

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9
Q

How do tertiary TCA’s work?

A

NE=5HT re-uptake inhibitor

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10
Q

What are the side effects of TCAs associated with blocking the H1 receptor?

A

Sedation and weight gain

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11
Q

What are the side effects of TCAs associated with blocking the M1 muscarinic receptors?

A

sedation, confusion, blurred vision, urinary retention, dry mouth, constipation

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12
Q

What are the side effects of TCAs associated with blocking the alpha-1 adrenergic receptors?

A

sedation, orthostatic hypotension, dizziness

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13
Q

What are the side effects of TCAs associated with blocking serotonin vs NE re-uptake?

A

Serotonin: sexual dysfunction
NE: hypertension, sweating

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14
Q

IN order, what are the receptors bound by TCAs (from receptors bound at lowest concentration to receptors bound at highest concentration)

A
Histamine
ACh
--Anti-depressant efficacy-- (NE and 5HT)
CNS toxicity (about 4x drug efficacy)
CVS toxicity (about 5x drug efficacy)
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15
Q

In what age group should TCA’s be avoided?

A

Elderly- they are more susceptible to the side effects due to decreased renal and hepatic function, and they are also more likely to have polypharmacy- other drug interactions

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16
Q

Describe the therapeutic index of TCAs

A

The therapeutic index is narrow- avoid giving it to anyone who is at risk for overdosing, as ingestion of a 2 week supply can be lethal

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17
Q

How do TCAs cause cardiac problems?

A

They block fast Na+ channels in the myocardium –> prolonged action potential, prolonged QRS interval –> cardiac conduction defects and potentially lethal arrhythmias

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18
Q

When does selegiline work as an antidepressant?

A

At high doses, when it begins to inhibit MAO-A

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19
Q

MAO-I’s combined with what classes of drugs can lead to serotonin syndrome?

A

Antidepressants, Opioids

Mirtazapine, SNRIs, TCAs, SSRIs

20
Q

MAO-I’s combined with what classes of drugs can lead to a hypertensive crisis?

A

Sympathomimetics
Antidepressants (all but SSRIs)
OTC cold remedies

21
Q

Tertiary TCAs are metabolized to become what?

A

Secondary TCAs

22
Q

Imipramine is metabolized to what drug?

A

Desipramine (a secondary TCA)

23
Q

Amitriptyline is metabolized to what drug?

A

Nortriptyline

24
Q

Why should TCAs be avoided in people that take other CNS depressants (alcohol, barbiturates, opiates, benzodiazepines)?

A

Because of additive effects that can lead to over-sedation or possible death

25
Q

Where are TCAs metabolized?

A

In the liver - CYP450 system

26
Q

Of the SSRIs, which one has the highest affinity for 5HT, NE and Dopamine receptors compared to when it begins to bind the other histamine, muscarinic etc receptors?

A

Sertraline

27
Q

Which of the antidepressants has the longest half-life?

A

Fluoxetine: it has the longest half-life of all the drugs used in psych

It’s half life (1-4 days) is extended as the active metabolite is 7-15 days!

Important: If fluoxetine interferes with another drug through the CYP450 system, it’s going to take a looonnnggg time to clear out

28
Q

Which two SSRIs are strong CYP 2D6 inhibitors?

A

Fluoxetine and Paroxitine

29
Q

Which two SSRIs have the shortest half-life of the SSRIs? What is the risk of such a short half life?

A

Paroxetine and Fluvoxamine

Short half life –> most likely to undergo withdrawal symptoms with a missed dose

30
Q

What’s the difference between citalopram and Escitalopram?

A
Citalopram = both isomers
Escitalopram= pure S isomer (the active compound)
31
Q

Which SSRI is the prototype?

A

Fluoxetine – therefore the least 5-HT selective

32
Q

Which SSRI has the highest affinity for the 5HT transporter?

A

Paroxetine

33
Q

How does Paroxetine affect its own metabolism?

A

Paroxetine slows its own metabolism (as a CYP 2D6 inhibitor)

34
Q

List the relative receptors bound by Venlafaxine in order

A

5HT , NE, Dopamine …THEN all the side effects

As a result, side effects are related to serotonin and NE

35
Q

Are venlafaxine and dualoxetine associated with discontinuation syndrome?

A

Yes- they both have relatively short half-lives

36
Q

What is the MOA of mirtazapine?

A

Blocks both NE and Serotonin alpha-2 autoreceptors

37
Q

What is the MOA of bupropion?

A

NE and dopamine re-uptake inhibitor

38
Q

How does Mirtazapine have no low side effects associated with nausea, sexual dysfunction, insomnia and anxiety?

A

Mirtazapine also blocks 5-HT2A, 5-HT2C and 5-HT3

39
Q

What are the major side effects associated with mirtazapine?

A

Histamine binding –> weight gain, dry mouth, and sedation

40
Q

What are the effects of bupropion in the liver?

A

Strong CYP2D6 inhibitor

41
Q

What is the MOA of nefazodone?

A

5HT re-uptake inhibitor

5HT-2A receptor antagonist

42
Q

What are the side effects of nefazodone?

A

No sexual side effects, sedation

43
Q

How long does it take cells to regenerate MAOs after stopping MAO-Is?

A

10-14 days

44
Q

How long do you have to wait after stopping a RIMA for the effects to wash out?

A

1 day - RIMAs are reversible

45
Q

After stopping any antidepressant to switch to an MAO-I, how long do you have to wait?

A

5 half lives for the drugs to clear (about a week)