L5-6 Antidepressants Flashcards

1
Q

If a patient is on an antihypertensive drug already, which of the TCAs is the best to give?

A

Nortriptyline

would not contribute to an even lower BP (through alpha blockade)

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2
Q

What are the uses of TCAs?

A

Depression

Panic Disorder

Pain

Fibromyalgia

Enuresis-Imipramine

ADHD

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3
Q

Name the TCA tertiary amines.

What is significant about them?

A

Imipramine

Amitriptyline

Trimipramine

Doxepin

  • more sedating than secondary amines
  • more serotonin effect
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4
Q

Name the TCA secondary amines.

What is significant about them?

A

Desipramine

Nortriptyline

Protriptyline

  • less sedating
  • more NE effect
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5
Q

What are the two TCA drugs you would NOT want to give in patients with pre-existing cardiac problems?

A

Imipramine (tertiary) and desipramine (secondary)

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6
Q

What is the mechanism of action of the TCAs?

What are the three receptors do TCAs block?

A

TCAs inhibit the uptake of NE and serotonin.

Histamine blockade: drowsiness and sedation, tolerance develops in 1 wk

Muscarinic blockade (anti-cholinergic): impairment of memory and cognition

Alpha blockade: postural hypotension, dizziness, reflex tachycardia

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7
Q

What are the autonomic effects of the TCAs?

With with TCAs are these most likely to be seen?

A

Cholinergic blockade: blurred vision, tachycardia, palpitations, constipation, urinary retention, dry mouth, metallic taste, gastric distress

More common with the tertiary compounds.

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8
Q

Why do the TCAs cause analgesia?

A

Due to a direct action of descending noradrenergic pathways in the spinal cord, activating endorphin neurons in the dorsal horn. This, in turn, decreases release of Substance P.

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9
Q

What are the cardiac effects of the TCAs?

A

Most common: orthostatic hypotension and tachycardia due to **alpha blockade and anti-cholinergic effects. **Can potentiate effect of antihypertensives.

Cardiac depression (more severe in patients with conduction defects or on Class I anti-arrythmatics)

Increased irritability

Can lead to ventricular arrhythmias (Torsades de pointes), can see inverted or flattened T waves

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10
Q

What patients should never be given TCAs?

A

Previous MI

BBB

Use caution in: seizure patients (decrease seizure threshold), patients with cardiac problems or who are on antiarrythmatics

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11
Q

What are the CNS effects of TCAs?

A

Sedation, drowsiness (histamine blockade)

Weakness, fatigue

Worse with tertiary TCAs

Anti-cholinergic: delirium at toxic doses

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12
Q

What are some side effects of TCAs that are not autonomic, cardiac, or CNS related?

A

weight gain

decreases the seizure threshold

SIADH: water intoxication, hyponatremia

Sexual dysfunction

Some physical dependence: muscle aches and malaise if stopped abruptly

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13
Q

Can TCAs be used in pregnancy?

A

YES

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14
Q

What are some basic pharmacokinetic principles with the TCAs?

A

Well absorbed orally

Long half-lives

Significant protein binding

Metabolized in liver-interactions common

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15
Q

What are the effects of a TCA overdose?

A

Cardiac conduction defects and arrythmias-torsades de pointes

Severe hypotension

Agitation, delirium

Neuromuscular irritability and seizures

Hyperpyrexia

Coma, shock, metabolic acidosis

Respiratory depression

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16
Q

How do you treat a TCA overdose?

A

Cardiac monitoring, supportive care

Gastric lavage, charcoal

Magnesium, isoproterenol, cardiac pacing for torsades de pointes

Lidocaine, propranolol, phenytoin to manage arrythmias and seizure prevention

Sodium bicarb and potassium chloride to restore acid base balance

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17
Q

What is the big drug interaction with TCAs?

A

MAOIs = serotonin syndrome: CNS toxicity, hyperpyrexia, convulsions, coma

SSRIs= compete for metabolism-toxic levels

Clonidine: decrease effectiveness–>leads to hypertension

Amphetamines: hypertension

Potentiate effects of other CNS depressants and alcohol

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18
Q

What is Clomipramine?

A

A TCA approved for use in OCD. Works similarly to SSRIs.

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19
Q

What is the mechanism of action of MAOIs?

A

Inhibits MAO-A and MAO-B

Monoamine oxidase enzymes breaks down circulating catecholamines and compounds ingested from food (tyramine)

MAO-A breaks down NE and serotonin

MAO-B breaks down DA

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20
Q

Name the two MAOIs.

What are they used to treat typically?

A

Phenelzine and tranylcypromine both irreversibly inhibit borth MAO-A and MAO-B

Useful in aytpical depression that hasn’t responded to other drugs

Drug of last choice due to serious side effects

21
Q

What are the pharmacokinetics of the MAOIs?

A

metabolized in liver

effects persist for 1-3 weeks after discontinuing the drug due to long half-lives and irreversible inhibition of MAO

22
Q

What is the big dangerous side effect of the MAOIs?

A

HYPERTENSIVE CRISIS!

Irreversible inhibition of MAO in the GI tract allows accumulation of tyramine ingested in food

Tyramine causes release of catecholamines from nerve endings and adrenal medulla

Ingestion of foods containing tyramine can lead to severe hypertensive crisis which can produce fatal intracranial bleeding

Can also occur if MAOIs are taken with sympathomimetic drugs

Treated with alpha receptor blocker: phentolamine

23
Q

What are some drug interactions with the MAOIs?

A

OTC cold and cough meds: anything containing sympathomimetic amines such as phenyleprine, ephedrine, or amphetamines–>severe hypertension

TCAS or SSRIs–>serotonin syndrome

Meperidine, tramadol, dextromethorphan–>serotonin syndrome

Buspirone–>hypertension

USE CAUTION WITH ALL MEDICATIONS

24
Q

What does a MAOI overdose look like?

A

agitation, hallucinations, hyperreflexia, hyperpyrexia, convulsions, hypo or hypertension

25
Name the SSRIs.
fluoxetine sertraline paroxetine citalopram escitalopram fluvoxamine vortioxetine vilazodone
26
Name the SNRIs How do they work?
Venlafaxine (effexor) desvelafaxine duloxetine (cymbalta) milnacipran levomilnacipran Inhibit 5-HT and NE reuptake
27
What is the mechanism of action of SSRIs?
Inhibit re-uptake of serotonin into the synaptic terminal Alter expression of 5-HT receptors in long term DOC for depression Mild profile of side effects
28
How is fluoxetine different in its pharmacokinetics than the other SSRIs?
Extensively bound to plasma protein Half life of 2-3 days, then converted to active form that has half life of 7-9 days Paroxetine is the next longest half live (21 hours)
29
How does fluoxetine and paroxetine affect liver enzymes?
Fluoxetine and Paroxetine significantly inhibit CYP2D6 Inhibits metabolism or activation of many other drugs: other antidepressants, benzos, antipsychotics Decreases activation of some opiods so they can be less effective in pain management Decreases activation of tamoxifen, tx of breast cancer Other SSRIs have fewer effects on hepatic enzymes and shorter half-lives
30
What are the uses for the SSRIs?
Depression: DOC Panic Disorder: DOC OCD: fluoxetine, paroxetine, sertraline, clomipramine, and fluvoxamine Social anxiety: paroxetine and sertraline Bulimia: fluoxetine Alcoholism
31
What are the side effects of SSRIs?
GI: nausea, diarrhea, constipation, loss of appetite Weight loss and weight gain CNS stimulation: anxiety, insomina (fluoxetine, sertraline), sedation (paroxetine) Sexual dysfunction: decreased libido SIADH Photosensitivity
32
What are the drug interactions with the SSRIs?
MAOIs, St. John's Wort, amphetamines: serotonin syndrome TCAs: inhibition of metabolism increases TCA concentration and toxicity Warfarin: inhibition of metabolism, increased risk of bleeding Phenytoin or carbamazepine: increased anticonvulsant levels Beta-blockers: inhibition of metabolism so increased in concentrations can result in heart block and hypotension Opiods: less effective in treating pain, inhibits conversion of opiods to active compound by CYP2D6 Tramadol: seizures, serotonin syndrome Tamoxifen: decreases metabolism of pro-drug to active compound
33
Fluoxetine (Prozac)
SSRI very long duration of effect need to wait 5 weeks after discontinuing to switch to MAOl being tried for chronic pain because it has effects on NE re-uptake as well taken in morning-may cause insomnia, restlessness
34
Sertraline (Zoloft)
SSRI more selective for serotonin than fluoxetine approved for use in OCD and social anxiety as well as depression shorter duration of action and less inhibition of hepatic enzymes than fluoxetine
35
Paroxetine (Paxil)
more selective for serotonin duration of action shorter used in elderly approved for OCD and social anxiety More likely to cause sedation more likely to cause anorexia and insomnia **Contraindicated in pregnancy**
36
Citalopram and Escitalopram
Escitalopram is S-enantionmer of citalopram Escitalopram may have a faster onset of action (1-2 weeks) Little effect on CYP2D6-fewer pharmacokinetic drug interactions
37
Vortioxetine
SSRI inhibits serotonin transporters 5-HT 3a and 7 antagonist, 5-HT 1b partial agonist, 5-HT 1a agonist increases serotonegic activity Side effects-nauesea, diarrhea, dry mouth, abnormal dreams, sexual dysfunction
38
Vilazodone
SSRI and partial 5-HT 1a agonist lower incidence of sexual dysfunction
39
Venlafaxine and Desvenlafaxine
SNRI Inhibits re-uptake of both serotonin and NE long duration of action Desvenlafaxine now available for tx of depression, being tested for hot flashes and neuropathic pain
40
What are the adverse effects of Venlafaxine and Desvenlafaxine?
Increased BP SIADH
41
Duloxetine (Cymbalta)
SNRI Inhibits re-uptake of serotonin and NE Effective in improving physical symptoms moderate inhibition of CYP2D6
42
What are the adverse effects of Duloxetine (Cymbalta)?
anorexia, drowsiness, headache, insomnia, nausea/vomiting, dry mouth sinus tachycardia, constipation, diahrrea, dizziness May be hepatotoxic-do not give in liver disease Contraindicated in third trimester of pregnancy
43
Milnacipran and Levomilnacipran
SNRI Milnacipran: approved for fibromyalgia Levomilnacipran: approved for major depressive disorder Side effects: GI upset, increase BP
44
Bupropion (Wellbutrin)
inhibits re-uptake of dopamine and NE often works in patients who have not responded well to other antidepressants can be combined with SSRIs to increase effectiveness and decrease incidence of sexual dysfunction ADHD in children appears to reduce cravings
45
What are the side effects of Bupropion?
CNS stimulation: anxiety, insomnia, restlessness, tremor can induce psychosis (increased DA) weight loss headache, nausea contraindicated in patients with hx seizures or head trauma do not give in patients that are taking drugs that lower seizure threshold
46
Mirtazapine (Remeron)
antidepressant that blocks alpha2 receptors that normally inhibit release of NE and serotonin increases release of NE and 5-HT from nerve terminals Blocks 5-HT 2a and 3 which eliminates the normal side effects of SSRIs-anxietiy, insomnia, nausea, sexual dysfunction Blocks histamine receptors--\>drowsiness and sedation, increased appetite and weight gain
47
Atomoxetine
selective inhibitor of NE re-uptake First non-stimulant for treatment ADHD: increase memory and attention by increasing NE levels GI distress and insomnia liver damage is possible but rare
48
Amoxapine
some antipsychotic effect, may be useful in depression with schizophrenia DA receptor antagonism can cause Parkinson's like symptoms, amenorrhea, galactorrhea, tardive dyskinesia
49
Trazodone
partial agonist at 5-HT 1a, block 5-HT 2a fairly sedating, not very good antidepressant pain management and sleep aid Side effects: sedation, dizziness, hypotension, nausea, **priapism**