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Pharmacology > AntiDepressants > Flashcards

AntiDepressants Flashcards

1
Q

Typically, how long do anti-depressants take to exert their therapeutic effects?

A

4-6 weeks, though adverse effects from these drugs may start after the first dose

The effect at the drug’s target site is immediate, but clinical improvement takes weeks-months

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2
Q

What is the function of MAOs? How about MAO-A and MAO-B specifically?

A

Breakdown 5-HT and NE in serotonergic and dopaminergic axon terminals

MAO-A: metabolizes NE, Epi, and 5HT

MAO-B: metabolizes trace amines and 5HT when at high concs

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3
Q

MAOIs

MOA

A

Inhibit MAO enzymes to prevent breakdown of NE and 5HT in the axon terminals. More is thus released into the synaptic cleft

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4
Q

MAOIs

What are the two main kinds? What drugs are in each class?

A

Irreversible Inhibitors:
Phenelzine
Tranylcypromine
Selegiline

Reversibel Inhibitors:
Meclobemide (not available in USA)

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5
Q

MAOIs

Irreversible Inhibitors MOAs

A

Phenelzine and Tranylcypromide block MAO-A and MAO-B by irreversibly binding and inhibiting the enzyme

Selegiline preferentially blocks MAO-B. Acts as an antidepressant at high doses.

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6
Q

MAOIs

Pharmacokinetics (half life, etc)

A

Brief half life

Irreversible – bind enzyme and that’s it. Once bound to MAO, enzyme must be replaced, which could take 10-14 days

Reversible– drug and enzyme can uncouple in certain situations

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7
Q

MAOIs

Adverse Effects

A
  • Hypertensive Crisis
  • Serotonin Syndrome

Excess 5HT:
Nausea, vomiting
Sexual Dysfunction
Sleep disturbance

Excess NE:
Orthostatic hypotension

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8
Q

When could a hypertensive crisis occur in a patient taking a MAOI?

A

MAOI blocks MAOs in the liver, which can prevent metabolism of some compounds in foods (tyramine in cheeses). If they consume foods high in tyramine, tyramine levels are elevated in the blood and tyramine can act as a pressor

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9
Q

What is special about selegiline’s dosage that it may be used to prevent hypertensive crisis?

A

Used in a transdermal patch so it travels directly to brain without going through first pass metabolism in the liver. Minimizes risk for HTN crisis because MAOs in brain are inhibited before MAOs in the liver

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10
Q

MAOIs

Describe signs and symptoms of Serotonin Syndrome

A

Caused by excess 5HT

Myoclonus
Increased reflexes
High BP
Fever
Cardiovascular collapse
Altered mental status
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11
Q

Why are OTC cold remedies and antidepressants often a bad combination?

A

Could cause HTN crisis

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12
Q

List the Tricyclic Antidepressants (tertiary and secondary)

A

Tertiary
Imipramine
Amitryptaline

Secondary:
Desipramine
Nortriptyline

Clomipramine and Doxepin are tertiary, but act like secondary

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13
Q

How do the functions of tertiary and secondary TCAs differ?

A

Tertiary
NE = 5HT reuptake inhibitors

Secondary
NE > 5HT reuptake inhibitors

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14
Q

TCAs

Pharmacokinetics (Solubility, Vd)

A

High lipid solubility

High Vd

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15
Q

TCAs

Side Effects

A

Sedation – block H1, M1 muscarinic, a1 adrenergic receptors

Sexual dysfunction

HTN
Sweating

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16
Q

In what patients might you avoid using TCAs?

A

Elderly – avoid oversedation and confusion

Anyone on pain meds (CNS depressants) – risk of oversedation

Worried about people who might overdose. Worried about people who are on other drugs that will inhibit TCAs’ metabolism

17
Q

SSRIs

MOA

A

Block the 5HT reuptake pump on the presynaptic axon terminal, thus leaving 5HT in the synapse longer so it can bind its receptor

18
Q

List the SSRIs available

A 
Fluoxetine
Sertraline
Paroxetine
Citalopram
Escitalopram
Fluvoxamine
19
Q

Why are SSRIs beneficial over TCAs?

A

SSRIs have very low risk of side effects involving histamine, Ach, and NE receptors

20
Q

Which SSRI has the longest half life?

A

Fluoxetine (1-4 days) and its metabolite (7-15 days)

21
Q

What effects do SSRIs have on CYP450 enzymes?

A

Inhibitory effects on CYP450 enzymes

Fluoxetine and Paroxetine are strong inhibitors of CYP 2D6 enzymes

22
Q

Which SSRIs have the shortest half lives?

A

Paroxetine and Fluvoxamine

23
Q

Which SSRIs have the highest risk of discontinuation syndrome (withdrawal) if they are abruptly stopped?

A

Paroxetine and Fluvoxamine

24
Q

SSRIs

Side effects

A

GI upset
Anxiety
CNS
Sexual dysfunction

May only happen once or twice and then go away, or be intermittent. You need them to deal with side effects for some time (4-6 weeks) until they might actually see clinical improvement in symptoms

25
Q

SNRIs

MOA

A

Block reuptake at both the serotonin and NE reuptake pumps, leaving both 5HT and NE in the synaptic cleft longer

26
Q

What is the most commonly used SNRI?

A

Venlafaxine

Note: has a very short half life, so may have a discontinuation syndrome if abruptly stopped

27
Q

What are the two atypical antidepressants?

A

Buproprion

Mirtazipine

28
Q

Mirtazipine

MOA

A

Blocks alpha 2 adrenergic autoreceptors on NE and 5HT neurons

Also blocks histamine receptor, 5HT-2A, 2C, 3 (prevents potential side effects of excess serotonin)

29
Q

Mirtazipine

Side Effects

A

Weight gain

Sedation

30
Q

Buproprion

MOA

A

NE and DA reuptake inhibitor

31
Q

Buproprion side effects

A

No 5Ht or H1 related side effects

Increased seizure risk at high doses

32
Q

Nefazodone

MOA and Side Effects

A

Blocks 5HT reuptake
5HT-2A receptor antagonist

No sexual side effects, mild sedation

33
Q

Vilazodone

MOA and Side Effects

A

Blocks 5HT reuptake
Partial agonist at 5HT-1A receptors

Insomnia
GI upset

34
Q

Vortioxetine

MOA and Side Effects

A

Blocks 5HT reuptake
Agonist of 5HT-1A receptors
Partial agonist of 5HT-1B receptors
Antagonist 5HT-3 and 5HT-7 receptors

No sexual side effects or weight gain

35
Q

If you are switching from an MAOI to an antidepressant, how long should you wait to start the new med?

A

Need to wait for neurons to regenerate new MAO enzymes (they need to replenish those that have been irreversibly inhibited).

Wait 10-14 days

36
Q

Which two antidepressants are most likely to produce interactions with other drugs?

A

Fluoxetine and Fluvoxamine

Pharmacology (67 decks)

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