117b - Antidepressants Flashcards
Which classes of antidepressants are useful in the treatment of chronic pain?
SNRIs: increase 5HT at lowest does and NE at high doses; it is helpful for neuropathic pain;
TCAs
Which class of antidepressants is especially useful for treating migraine?
TCAs
(Especially amitryptiline)
Which amino acid is a precursor for serotonin?
Tryptophan
Tyrosine is a precursor for which neurotransmitters?
Dopamine, NE
(Dopamine is a precursor for NE)
List 3 common features of all classes of antidepressants
- Takes 3-8 weeks to be maximally effective
- All have equivalant response and remission rates
- 50-70% response
- 35-50% remission
- Placebo-drug differences depend on the level of severity of depression
- More severe depression = less placebo effect
If a patient experiences partial improvement at the maximally tolderated dose of antidepressant A, what is the next step in their management?
Add another antidepressant of a different class
OR
Target residual symptoms with other treatments
Remeber: The goal of treatment is complete response
c. Bupropion
- Helpful in depression w/o anxiety symptoms
- Will treat comorbid tobacco dependence
-
Bupropion (Wellbutrin) is an NE-DA reuptake inhibitor that acts as activating antidepressant so it often makes anxiety worse
- it doesn’t cause sexual dysfunction or weight gain
- it is useful in ADHD, nicotine dependence, and sexual dysfunction caused by other antidepressants
- contraindicated in seizure disorder and eating disorders
How should you select a first-line antidepressant?
(What factors should influence your decision?)
- Side effect profile
- Past response
- Comorbid medical and psichiatric problems
Remember: no significant differences in efficacy among first line medications
Consider psychotherapy in addition
Which classes of antidepressants are first line for treating depression?
- SSRI
- SNRI
- Mirtazapine
- Bupropion
Select agent based on side-effect profile
All have comparable efficacy
TCAs and MAOIs are not first line due to higher side effect burden, potential for lethal overdose
What are the 6 most common side effects of SSRIs and SNRIs?
Which ones usually improve?
- GI upset
- Anxiety, agitation
- Insomnia
- Headache
- Sweating
- Sexual dysfunction
All except sexual dysfunction usually improve
List 3 serious risks of antidepressant treatment
- Increased risk of suicidal thinking, behavior in young people
- Highest in the first few days on the medication
- Risk of treatment < risk of untreated depression
- Serotonin syndrome
- Do not give antidepressant monotherapy for anyone with bipolar disorder
- Increases manic episodes
What is serotonin syndrome?
How can it be avoided?
Result of increased 5HT activity in the brain, usually from multiple serotoninergic drugs
- Mental status change
- Hyperthermia
- Hyperreflexivity
Never combine MAOIs with TCAs or SSRIs
Which SSRI has the longest half life?
Why is this important?
Fluoxetine (Prozac)
- No need to taper, is easy to stop
- Requires long wash-out if transitioning to MAOI
Which SSRI has the highest risk of drug-drug interactions?
Why?
Paroxetine (Paroxil)
It is a potent CYP26 inhibitor
- has the shortest half life so if a patient misses a dose, they will notice the difference right away
Which SSRI has the shortest half life?
Why is this important?
Paroxetine
; it has the shortest half life so if a patient misses a dose, they will notice the difference right away —> Results in the worst discontinuation symptoms (must taper)
Which SSRI should be avoided in anyone with cardiac comorbidities?
Citalopram
- Citalopram (Celexa) is a SSRI that can cause QTc prolongation so should be avoided in cardiac disease
Which SSRI is preferred in pregnancy?
Sertraline
What is the most common side effect of the SNRIs?
Hypertension (at higher doses)
(In addition to the side effects common to all agents that increase 5HT and NE: GI upset, weight gain, sweating, sexual dysfunction)
What is the mechanism of action of TCAs?
Inhibit NE and 5HT reuptake
What are the common side effects of TCAs?
- all TCAs have “HAM” side effects:
- antiHistamine – setation, weight gain
- antiAdrenergic – hypotension, dizziness, reflex tachycardia, QTc prolongation
- antiMuscarinic – dry mouth, blurred vision, urinary retention, constipation, confusion
What special diet must be followed when a patient is on a MAOI?
What happens if they do not follow this diet?
Tyramine free diet: No aged cheese, red wine, fava beans, cured meats
Can cause hypertensive crisis if ingested while on MAOI
Which antidepressant should you prescribe to a patient that does not have anxiety symptoms and does not want to experience weight gain or sexual dysfunction?
Buproprion
May worsening existing anxiety symptoms
(Mirtazapine does not have sexual side effects, but can cause weight gain)
Which antidepressants carry the lowest risk of switch to mania if there is undiagnosed bipolar disorder?
Bupropion
Mirtazapine
What are the mechanisms of action of mirtazapine?
-
Mertazapine (Remeron) is an alpha 2 receptor antagonist, which increases NE and 5HT
- at low doses it preferentially blocks H1 (antihistaminic) helps anxiety and sleep
- at high doses it preferentially acts on NE receptor more activating
Which antidepressant is often used elderly patients with insomnia and low appetite?
Mirtazapine
Side effects of sedation and weight gain may be helpful!
What is the mechanism of trazodone?
-
Trazadone (Desyrel) is an 5HT antagonist and agonist that is used to treat insomnia
- the effective dose that would treat depression is limited by its side effects of sedation and orthostatic hypertension
- side effects include sedation, headache, and priapism
- to treat insomnia, use it at lower dose
Which antidepressant has the potential side effect of priapism?
Trazodone
- side effects include sedation, headache, and priapism
priapism = prolonged erection of the penis
List the different SSRIs
-
SSRIs all selectively block the 5HT receptor; all are once a day dosing and have very low toxicity
- Fluoxetine (Prozac) has the longest half-life and is easy to stop; need to have a long washout b4 switching to a MAOI
- Paroxetine (Paxil) has more drug-drug interactions and is a potential CYP2D6 inhibitor; it has the shortest half life so if a patient misses a dose, they will notice the difference right away
- Citalopram (Celexa) can cause QTc prolongation so should be avoided in cardiac disease
- Escitalopram (Lexapro) has fewer side effects of Citalopram
Describe bupropion
-
Bupropion (Wellbutrin) is an NE-DA reuptake inhibitor that acts as activating antidepressant so it often makes anxiety worse
- it doesn’t cause sexual dysfunction or weight gain
- it is useful in ADHD, nicotine dependence, and sexual dysfunction caused by other antidepressants
- contraindicated in seizure disorder and eating disorders
Describe Trazadone
-
Trazadone (Desyrel) is an antidepressant; 5HT antagonist and agonist that is used to treat insomnia
- the effective dose that would treat depression is limited by its side effects of sedation and orthostatic hypertension
- side effects include sedation, headache, and priapism
- to treat insomnia, use it at lower dose
Describe Mertazapine
-
Mertazapine (Remeron) is an alpha 2 receptor antagonist, which increases NE and 5HT
- at low doses it preferentially blocks H1 (antihistaminic) helps anxiety and sleep
- at high doses it preferentially acts on NE receptor more activating
- side effects: sedation, weight gain, dizziness, dry mouth, constipation
- has no sexual side effects
- often used in depression w/ prominent insomnia and low appetite
- is dosed at bedtime b/c of its sedative properties
