Antidepressants Flashcards
1
Q
What are the natural and synthetic catecholamine agonists?
A
- natural
- epinephrine
- norepi
- dopamine
- synthetic
- isoproterenol
- dobutamine
2
Q
The receptors that are termed alpha receptors respond to the catecholamines in what order of potency?
A
Norepi > epi > isoproterenol
3
Q
The receptors that are termed beta receptors respond to the natural and synthetic catecholamines in what order of potency?
A
Isoproterenol > epi > norepi
4
Q
What is serotonin?
Where is it found in the highest concentration?
A
- 5-Hydroxytryptamine (5-HT)
- neurotransmitter and local hormone
- highest concentration:
- wall of intestine
- blood
- CNS
5
Q
What are the three types of antidepressants?
A
- Selective serotonin reuptake inhibitors
- tricyclic antidepressants
- Monoamine Oxidase Inhibitors
6
Q
What are SSRI’s used for?
A
- treat mild to moderate depression
- anxiety disorder
- panic disorder
- OCD
- post-traumatic stress disorder
- social phobia
- bi-polar depressive episodes
7
Q
What is the MOA of SSRI’s?
A
- All block reuptake of serotonin
- New SSRI’s act on serotonin, NE, and/or dopamine
- some produce alpha 2 receptor blockade
8
Q
What makes an SSRI atypical?
A
If it acts on dopamine
9
Q
What are the typical SSRIs?
A
- Fluoxetine (prozac)
- Sertraline (zoloft)
- Paroxatine (paxil)
- Fluvoxamine (Luvox)
- Escitalopram (Lexapro)
10
Q
Which antidepresent is the most potent inhibitor of CYP450?
A
Fluoxetine (prozac)
11
Q
Why are SSRIs the anti depressant of choice?
A
- Higher safety index than other classes
- minimal effects on blood pressure
- no issues with cardiac conduction
- no changes in seizure threshold
12
Q
What are the side effects of SSRI’s?
A
- Insomnia/ fatigue
- agitation
- orthostatic hypotension
- headache
- nausea/vomiting
- sexual dysfunction
- increased appetite
13
Q
What are the anesthetic considerations for SSRIs?
A
- inhibition of CYP450
- may increase plasma concentration of certain drugs
-
Antiplatelet activity
- increased risk of bleeding
- Serotonin syndrome-medication
- confusion, fever, shivering, ataxi, diaphoresis, hyperreflexia, muscle rigidity
14
Q
What are tricyclics used to treat?
A
- depression
- chronic pain syndrome in lower doses
- chemical structure is similar to local anesthetics and phenothiazines
- inhibits overactive inflammatory response systems
- Potentiation of endogenous opioids
15
Q
Tricyclic MOA
A
- Blocks reuptake of serotonin and/or NE at presynaptic terminals
- tertiary amines- inhibits serotonin and NE reuptake
- secondary amines- inhibit NE reuptake
16
Q
What are the tertiary amine tricyclics?
A
- Amytriptyline (elavil)
- Imipramine (tofranil)
- clomipramine (anafranil)
17
Q
What are the secondary amine tricyclic medications?
A
- Desipramine (norpramin)
- nortriptyline (pamelor)
18
Q
What are the pharmacokinetics of tricyclics?
A
- highly lipid soluble
- strongly PB
- long elimination 1/2 time
- 10-80 hours
- metabolized in liver
- all have active metabolites
19
Q
What are side effects of tricyclics?
A
- Anticholinergics
- dry mouth, tachycardia, urinary retention, ileus, slow gastric emptying
- cardiovascular
- orthostatic hypotension, modest increase in heart rate, depresses conduction through the atria & ventricles
- Central nervous system
- lower sz threshold, weakness, fatigue
- **these effects can be fatal with overdose
20
Q
Why would you not give a tricyclic with an MAOI?
A
- Can cause CNS toxicity
- hyperthermia
- sz
- coma
21
Q
What anesthetic drugs can have potential interactions with tricyclics?
A
- sympathomimetics
- IA
- anticholinergics
- antihypertensives
- opioids
22
Q
What should you consider when administering sympathomimetics to a patient on tricyclics
A
- response unpredictable
- exaggerated responses to indirect acting due to larger amounts of NE available to stimulate post synaptic receptors
- Use lower doses of direct acting
- decrease by 1/3
- Book says you could use an indirect acting sympathomimetic if the patient had been on their tricyclic chronically, but that gets fuzzy and riskly. We are risk avoiders.
23
Q
What should you expect regarding your volatile anesthetics if your patient is on tricyclics?
A
may need a higher MAC because of the extra NE that is not be re-taken up (theoretical, may not translate to practice)
24
Q
What should you expect if you administer epinephrine, opioids, or barbs to a pt on tricyclics?
What is the take home?
A
- They will have a greater response to all these meds
- decrease dose
- don’t forget about epi in a LA
25
What should you expect if you administer anticholinergics to a pt on tricyclics?
* They may have an exaggerated response
* more likely to have post op delirium and confusion
* glyco is better
26
What does anticholinergic toxicity or central anticholinergic syndrome look like?
* flushing
* dry mouth
* skin
* mydriasis (pupil dilation)
27
What can an overdose of tricyclics cause?
How does this present?
* life threatening intractable myocardial depression or ventricular dyrshythmias
* present as:
* agitation
* excitement and deliuium
* sz
* progresses to coma
* resp depression
* cardiac dyrshythmias
* sudden death
* hypotensive
* anticholinergic effects
28
How is a tricyclic overdose treated?
* ventilatory support
* manage CNS and cardiac toxicity
* physostigmine for anticholinergic psychosis
* acidosis may increase unbound drug--more dyrshythmias
* use bicarb
29
What does the MAO enzyme system deactivate?
dopamine
serotonin
epinephrine
norepi
30
What is the MOA of MAOIs?
* blocks the enzyme that metabolized biogenic amines, increasing the availability of these neurotransmitters in the CNS and PNS
* forms a stable, irreversible complex with MAO enzyme
31
Why aren't MAOIs used often?
* side effects
* lethal in overdose
* difficult dosing
* pt must follow a tyramine free diet
32
What are the MAO A's?
MAO B?
* MAO A
* serotonin
* NE
* epi
* MAO B
* phenylethylamine
33
What disease have we recently learned about that might be treated with an MAO B?
What should be considered in the dosing of this drug?
* Parkinson's
* If the dose is \>30 mg, it is no longer selective and will work on A enzymes as well
* if this happens, the patients diet will matter, just like it does with an MAO A
34
What are the side effects of MAOIs?
* Orthostatic hypotension (especially in elderly)
* anticholinergic like effects
* impotence/anorgasmy
* weight gain
* sedation or mild stimuland effects
35
What are the dietary restrictions for MAOIs?
why?
* tyramine- derived from tyrosine and can act as an idirect catecholamine releasing diet
* must follow diet that is low in tyramine
* to avoid Hypertensive crisis, CVA
* ex:cheese, fava beans, wine, avocado, liver, cured meats
36
What drugs should you use with caution with MAOIs?
* cyclic antidepressants
* opioids
* cold-allergy drugs
* sympathomimetics
* nasal decongestants
* SSRIs
* **no meperidine**
37
What symptoms should patients on MAOIs report that might indicate they are experiencing a catecholamine surge?
serious headache
vomiting
chest pain
38
Whats the deal with Demerol and pts on MAOIs?
* excitatory (type 1)- caused by enhanced serotonin activity in the brain
* agitation
* skeletal muscle rigidity
* hyperpyrexia
* depressant (type 2)- slowed breakdown of meperidine
* hypotension
* respiratory depression
* coma
39
Anesthetic considerations for MAOIs are basically the same as for tricyclics. What are they?
* caution with sympathomimetics- no direct acting!
* caution with opioids- no demerol!
* may need higher MAC with VA
* minimize possibility of sympathetic nervous stimulation or drug induced hypotension
40
What are the symptoms of MAOi overdose?
* excessive sympathetic discharge
* tachycardia
* hyperthermia
* mydriasis
* sz--\>coma
* treatment
* supportive care
* maybe dantrolene
41
What symptoms may be experienced when antidepressents are discontinued?
How can this be avoided?
* dizziness
* myalgias
* parasthesia
* irritability
* insomnia
* visual disturbances
* tremors
* lethargy
* N/V/D
* wean off over two weeks
