Antidepressants Flashcards

1
Q

____ weeks before new MOA A and B are synthesized

A

2 weeks

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2
Q

What is the mechanism of MOA A inhibitor toxicity

A
  • decreased amine degradation
  • amphetamine like effect and increased catecholamine release from intracellular vesicles
  • decreased amine reuptake
  • increased amine release
  • tranylcypromine; GABA antagonism; metabolized to amphetamine
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3
Q

What are the 4 phases of MOA A overdose

A
  1. asymptomatic (latent)
    - up to 6-12 hours
  2. neuromuscular excitation and sympathetic hyperactivity
    - hypertension
    - tremor
    - hyperreflexia
    - hyperthermia
    - diaphoresis
    - seizures
    - rigidity
  3. CNS depression and possible CV collapse
    - hypotension
  4. secondary complications for survivors
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4
Q

What is the tx of severe hypertension with MAO overdose

A

a short acting agent

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5
Q

What is the tx of arrhythmias associated with MAO overdose

A

standard antiarrhythmics

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6
Q

What is the tx of hypotension associated with MAO overdose?

A
  • direct acting vasopressors- start low
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7
Q

What is the tx of rigidity associated with MAO overdose

A

benzos, dantrolene, to prevent rhabdomyolysis

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8
Q

What foods should be avoided with MAO inhibitors

A
  • cheese
  • alcoholic beverages
  • fish
  • meat
  • fruit (overripe, banana peels)
  • yeast extracts
  • sauerkraut
  • beans
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9
Q

What is the cheese reaction?

A
  • hypertensive crisis (indirect acting amines, direct acting do not require MAO for their metabolism; catabolized by COMT)
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10
Q

What is tyramine?

A
  • a major dietary amine

- indirect acting agonists

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11
Q

Does tyramine cross the BBB

A
  • no
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12
Q

What is the effect of tyramine?

A
  • causes NE release from peripheral noradrenaline neurons
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13
Q

What is the mechanism of action of TCAs?

A

blocks 5HT and NE reuptake

- also reputes histamine, muscarinic and alpha adrenergic receptors

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14
Q

In usual doses, what is the cardiac effects of TCAs?

A
  • hypertension, tachycardia
  • slowed cardiac conduction
  • antiarrhythmic properties
  • orthostatic hypotension
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15
Q

What are the high risk patients for TCA overdose?

A
  • elderly
  • cardiovascular disease
  • drug interactions
  • overdose cases
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16
Q

What are the central anticholinergic effects of TCAs?

A
  • agitation
  • hallucinations
  • confusion
  • sedation
  • coma
  • seizures
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17
Q

What are the peripheral anticholinergic effects of TCAs?

A
  • hypertension
  • tachycardia
  • hyperthermia
  • mydriasis
  • dry, flushed skin
  • decreased GI motility
  • urinary retention
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18
Q

What are the cardiovascular specific effects of TCAs?

A
  • intraventricular conduction delay
  • sinus tachycardia
  • ventricular arrhythmias
  • hypotension
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19
Q

What are the CNS effects of TCAs?

A
  • coma
  • delirium
  • myoclonus
  • seizures
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20
Q

What are the risk factors that increase the risk of toxicity of TCAs?

A
  • pre-existing heart condition
  • electrolyte abnormalities
  • hepatic insufficiency
  • stimulant drug use (concomitant stimulant drug use)
  • multiple drugs that increase QT intervals
  • increase drug dosage
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21
Q

What is the general management strategies for TCA overdose?

A
  • support airways
  • cardiac monitoring
  • EKG
  • if decreased LOC: O2, dextrose, naloxone, thiamine, ABGs
  • stomach lavage
  • charcoal 50-100 g + cathartic
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22
Q

What is the life threatening dose of TCAs?

A
  • 10-20 mg/kg is considered life threatening
  • limit rx to 1 g if pt is suicidal
  • sx from as little as 3-4 times daily dose
23
Q

What is the most common cause of death with TCAs?

A
  • refractory hypotension (due to vasodilation or impaired cardiac contractility)
24
Q

What is the tx of orthostatic hypotension?

A
  • intravascular volume expansion
  • sodium bicarbonate, vasopressors or ionotropes (dopamine)
  • correct hyperthermia, acidosis, seizures
25
What is given as tx for CNS toxic effects?
- supportive tx | - benzos
26
Coma usually resolves in ______
24 hours
27
Acidemia from seizures may predispose to _______
arrhythmias
28
What are seizures usually treated by?
- IV benzos, midazolam infusion(if patients are actively seizing)
29
What is used for refractory seizures?
- barbiturates or propofol
30
Are drug levels a good predictor of whether or not someone will have a seizure
NO
31
What is the most common mechanism of death with cardiac toxicity?
- myocardial depression, ventricular tachycardia, or ventricular fibrillation
32
What is a good predictor of arrhythmias?
- QRS duration (should be >0.10 s)
33
_________ has a dramatic effect on narrowing QRS
sodium bicarbonate | this reduces arrhythmias and hypotension
34
What is the mechanism of cardiac toxicity?
- reductions of extracellular K or increase in extracellular Na - improves membrane responsiveness and increase conduction velocity - increase in serum pH may result in reductio of free TCA - unbound drug correlates with tissue uptake
35
Describe a lipid rescue- lipid emulsion
- TCAs= highly lipophilic - indication: refractory cardiotoxicity for overdoses of lipophilic medications - (TCAs, local anesthetic poisoning)
36
How long should someone be monitored for in the ICU post TCA OD?
- in the ICU for 12-24 hours after all sx are resolved
37
What are the s/s of overdose with venlafaxine?
- seizures, hypotension, sinus tachycardia
38
Serotonin toxicity was _____ common with venlafaxine compared to TCAs
more
39
Is blood pressure increases dose dependant with venlafaxine?
- YES IT IS (risk increases with increased age)
40
When is venlafaxine CI'ed in patients?
pre-existing seizures and cardiac diseases
41
What is the normal half life of venlafaxine, and what can it be extended up to in overdose?
5 hours normally, 15 hours with toxicity
42
What are the s/s associated with duloxetine overdose?
- somnolence - serotonin syndrome - seizures - vomiting
43
What is the risk of QRS prolongation and arrhythmias with duloxetine?
- LOW
44
What are the toxic effects of SSRIs?
- tremor - sinus tachycardia - n/v, diarrhea - obtundation - seizures - serotonin syndrome - mild bradycardia may occur in OD as well
45
What is the tx of antidepressant overdose?
- charcoal and supportive care
46
What are some of the causes of serotonin syndrome?
- inhibition of breakdown of 5HT (MAO inhibitors) - blocking reuptake of 5HT (SSRIs, clomipramine, DM, meperidine, cocaine, venlafaxine) - 5HT precursors or agonists (lithium, bispirone, LSD) - enhance 5HT release (MDMA)
47
What is the treatment 5HT syndrome?
- supportive care - neuromuscular symptoms (benzos) - increased temp (tylenol, cooling blankets) - severe rigidity (dantrolene) - severe sx: cyproheptadine 4 mg po q4h
48
What are the s/s of serotonin syndrome?
- agitation - mental status changes (confusion, hypomania) - diaphoresis - diarrhea - fever - shivering - incorporation - myoclonus - tremor - hyperreflexia
49
When should only 20 mg of citalopram be used?
- 20 mg should only be used in the elderly and in those with hepatic impairment
50
What is the safety profile of buproprion?
- may cause sinus tachycardia but not usually associated with conduction abnormalities
51
What is the MOA of mitazipine toxicity?
- increased 5HT and NE + serotonin blocker - mild-moderate anticholineric - antihistamine effects
52
Watch for ________ and ______ effects in overdose of mirtazapine
anticholineric and serotonergic
53
What are the usual s/s of mirtazapine toxicity?
- decreased LOC - tachycardia - hypertension - no QTc prolongation; no arrhythmias - NO seizures or serotonin toxicity