Psychopharmacologics Flashcards
What is the response in the elderly population and antidepressants?
Elderly are at risk for drug toxicity
- may not be able to tolerate antidepressants
- have neuronal changes that can decrease their response to these medications
How are antidepressants classified?
Classified based on their chemical structures and neuropharmacologic effects
True or False the MOA of antidepressants is known
False. UNKNOWN
- thought process: they act by altering non-adrenergic neurotransmission and/or serotoninergic neurotransmission
- Lead to believe that antidepressants work by increasing the amount of norepinephrine & serotonin in synapses.
What are the most broadly prescribed antidepressants ?
SSRIs
- drug of choice for mild to moderate depression
- 1st line treatment for panic disorder and obsessive compulsive d/o.
What is the MOA of SSRIs?
- Block the reuptake of serotonin - which then increases the amount of serotonin
What is the MOA of SNRIs
act on serotonin & norepinephrine pathways in the brain by a variety of mechanisms
- Enhance serotengic activity
What do SSRIs lack?
They lack anticholinergic properties
Can a person overdose on an SSRI?
No not really
What are common side effects of SSRIs?
- Insomnia
- Agitation
- Headache
- Nausea
- Diarrhea
- SEXUAL DYSFUNCTION (main reason for non-compliance) - decreased libido, anorgasmia, delayed ejaculation
- Abrupt d/c = dizziness & parenthesis, visual disturbance
Which SSRIs have a short half-life and require tapering?
Paroxetine & Venlafaxine
What is the Black Box Warning for SSRIs?
In children and adolescents = increased risk to have suicidal tendencies
Prozac- Fluoxetine side effects
- Nausea
- Anorexia
- Insomnia
- Sexual dysfunction
- Agitation
- Neuromuscular restlessness
- Effective analgesic for chronic pain that is associated with RA
- Does not cause hypotension
- Bradycardia & syncope in elderly
- If discontinuing & trying to switch to an MAOi - need to wait 5 weeks for the washout
What is the most potent inhibitor of certain hepatic cytochrome P-450 enzymes?
Prozac- Fluoxetine***
If you combine Prozac with an MAOi what will happen?
Serotonin Syndrome***
What is Serotonin Syndrome?
- Agitation/restlessness, insomnia, Confusion, RAPID HR & HTN
Dilated pupils, loss of muscle coordination or twitching of muscles, heavy sweating, diarrhea, headache, shivering, erector pili
Mild symptoms can go away within a day or two when you stop taking that medication or take drugs that block serotonin*
- Syndrome can start w/in hrs of taking a new drug or increasing the dose of a drug you’re already taking
When does Serotonin Syndrome become life threatening?
- High fever
- Tremor
- Seizures
- Irregular heartbeat
- Unconsciousness
What is the treatment for Serotonin Syndrome?
Most cases mild = stop medication
- benzos may help
- cyprohepatadine (a serotonin 2A antagonist), 12 mg orally- followed by 2 mg every 2 hrs
- H1 receptor antagonists receptors (an antihistamine) which is also used to treat Cushing’s syndrome too
- Methylene Blue is not supposed to be administered to patient using psychopharmacology SSRIs
How does sertraline (Zoloft) SSRI compare to Prozac?
Similar but less potent inhibitor of hepatic microsomes enzymes than Prozac
- can cause more gastric symptoms (nausea diarrhea)
- less insomnia & agitation
- Has an active metabolite w/ half life of 60-70 hrs
What is the recommended washout period of Sertraline (Zoloft) before starting an MAOI
14 days
Very different than Prozac- 5 weeks
What is the half-life of Paroxetine (Paxil) SSRI?
24 hrs
What SSRI should you caution because it enters into the breast more than others?
Paroxetine (Paxil)
True or False: Paroxetine (Paxil) decreases the effects of Warfarin
False: enhances the anticoagulant
What fatal rhythm can be caused from Citalopram (Celexa)/ Escitalopram (Lexapro)
Citalopram causes prolonged dose-dependent QT interval prolongation which places pts at risk for TORSADE’S de Points*
- Escitalopram does too, but to a lesser degree
What SSRI is effective for smoking cessation?
Bupropion
When will you see therapeutic effects of Bupropion?
2-4 weeks
MOA of Bupropion
Inhibition of dopamine & norepinephrine reuptake
Can Bupropion cause serotonin syndrome
Yes. Bupropion is an SSRI and cause serotonin syndrome
Venlafaxine (Effexor XR)
SNRI - inhibits reuptake of norepinephrine and serotonin
- Potentiate the action of dopamine in the CNS**
- efficacy like TCAs
- Metabolized by CYP450 enzymes & is a weak inhibitor of these enzymes
- Elimination T1/2 is 5 hrs & it does have an active metabolite for 11 hrs
- Do not use with an MAO inhibitor, washout period is 24 days
At high doses Venlafaxine (Effexor XR) can what affect on BP?
At high doses: 5-7% have diastolic blood pressure increases
Duloxetine (Cymbalta)
SNRI - Serotonin & Noradrenaline (NE) reuptake inhibitor similar to Venlafaxine
- For major depression, fibromyalgia, diabetic neuropathy
- S/E: nausea dry mouth, insomnia, sexual dysfunction
- no significant changes in BP
AVOID if renal dysfunction &/or chronic liver disease
Trazodone
Inhibits serotonin reuptake & norepinephrine & may also act as a serotonin agonist due to the active metabolite
What drug is good for management of depression but is better for insomnia ?
Trazodone - SNRI
- insomnia is induced by SSRIs or Bupropion
- S/E: sedation, orthostatic hypotension, nausea, vomiting, priapism in males,
- take at night
What is the anesthetic implication for SSRIs?
- SSRIs should be continued throughout the perioperative period
- Can cause HYPONATREMIA in the elderly
- Increase the risk of bleeding by inhibiting serotonin reuptake by platelets
- takes two to three weeks for a full washout
What medications do you have to be careful giving with an SSRI?
Any drug that relies on hepatic metabolism:
- Specifically Beta Blockers, Benzos, Antiarrhythmics, and any other serotonergic medication that can cause serotonin syndrome.
What are the Anesthesia implications for SNRIs?
- Cause a dose dependent increase in BP**
- S/E: increased sweating, tachycardia, & urinary retention
- Severe symptoms recur when abruptly stopped esp. venlafaxine & desvenlafaxine b/c they have short T1/2 lives
When would you use a TCA (Tricyclic Antidepressant)?
Moderate to severe treatment resistant depression
- most commonly used as adjunct analgesic in the management of both neuropathic & somatic chronic pain
Amitriptyline is a prototype
What are the main side effects of TCAs?
Anticholinergic effects:
- orthostatic hypotension - urinary retention - constipation - dry mouth - blurred vision - confusion
Other s/e:
- weight gain - sexual dysfunction - cardiac conduction delay
Why are TCAs hardly used anymore?
Narrow Therapeutic Index!
- potentially lethal in an overdose = resulting in part d/t inhibition of sodium channels, reflecting a slowing of conduction of cardiac impulses & appearance of life-threatening cardiac dysrhythmias
What drugs do TCAs interact with in anesthesia?
Sympathomimetics
- increased peripheral catecholamines from TCA may produce exaggerated responses to indirect acting vasopressors such as EPHEDRINE
Halogenated agents
- an increase in CNS catecholamines may increase the MAC of an inhalation agent
Anticholinergics Antihypertensives Opioids TCAs bind to plasma albumin Phenytoin, aspirin, & scopolamine
Contraindicated to use Amitriptyline in patients who have: (5)
- History of heart disease
- Conduction disorders
- Arrhythmias
- Heart failure
- Closed angle glaucoma
How are MAOIs dosed in the elderly?
Same dose for young people as for elderly people.
- Elderly often have higher MAO levels & the metabolism does not seem to be affected by age.
MAO-A is found where and what is it known to do?
MAO-A is found in the brain and the enzyme is known to breakdown (deaminate)
- Serotonin
- Epi
- Norepi
What drugs should be avoided in patients taking an MAOI?
- Cyclic antidepressants
- Prozac
- Cold/allergy medications
- Nasal decongestants
- Sympathomimetics drugs
- Opioids
What is the blood pressure response associated with MAOIs?
Hypertensive crisis
Which are physiologic effects associated with serotonin syndrome?
A. Hyperthermia
B. Hypocalcemia
C. Bradycardia
D. Autonomic instability
A. Hyperthermia
D. Autonomic instability
Which medication should be used to treat hypotension in a patient taking an MAOI?
Phenylephrine due to the direct alpha and not using endogenous catecholamines like ephedrine.
- Ephedrine causes an exaggerated hypertensive response
Your patient is taking Lithium, you know this will affect your anesthetics how?
Decrease IV anesthetics & inhalation agents with patients on Lithium
A patient ingested ecstasy & presents with hyperthermia, muscle rigidity, & mydriasis. What is the MOST appropriate treatment?
A. Cyproheptadine
B. Methylene Blue
C. N-Acetylcysteine
D. Dantrolene
A. Ecstasy can cause serotonin syndrome
- signs include:
- akathisia, agitation, coma, tremor, clonus, muscle rigidity, & midrasis
- Cyproheptadine (5-HT32a antagonist) is the treatment for serotonin syndrome
What drugs are associated with Serotonin Synd. (Nagelhout chart)
- MAOIs
- SSRIs
- SNRIs
- TCAs
- Linezolid (ABX)
- Opiate analgesics (Meperidine, Fentanyl, Tramadol)
- Dextromethorphan (OTC cough med)
- Almotriptan & sumatriptan (antimigraine)
- Amphetamine, Cocaine, MDMA/ECSTASY, LSD
- Antiemetics - Metoclopramide & Ondansetron
- Anticonvulsants - Carbamazepine & Valproic acid
- Herbals - Ginseng, nutmeg, & St. John’s wort
- Others - Lithium, Methylene Blue, Buspirone, Tryptophan
