Antidepressants Flashcards
Drug Induces Depression
Antihypertensive and cardiovascular
Sedative hypnotics
anti-inflammatory and analgesics
steroids
Risk of recurrence of depression
1 episode: 50-6-%
2 episodes: 70%
3 episodes: 90%
Biogenic amine hypothesis of depression
Reserpine causes depression by depleting NE and 5HT from vesicles
Neuroendocrine hypothesis of depression
overactivity of hypothalamic-pituitary adrenal axis causes an elevation of cortisol releasing factor which increases depression symptoms (causes insomnia, anxiety, decreased appetite and libido)
Neurotrophic hypothesis of depression
Brain-derived neurotrophic factor (BDNF) is decreased when experiencing pain and stress (so we want to increase BDNF levels to treat depression Sx)
BDNF has ‘antidepressant’ activity in animals
BDNF is important for neuronal connections
Integration of hypotheses of depression
- HPA and steroid abnormalities regulate BDNF levels
- Hippocampal glucocorticoid receptors are activated by cortisol during stress (decreasing BDNF)
- chronic activation of monoamine receptors increase BDNF signaling (through neurotrophic pathway)
- chronic activation of monoamine receptors leads to down regulation of HPA axis (through neuroendocrine)
Delayed therapeutic response of antidepressants
SSRI will cause an immediate increase of 5HT in brain, but clinically the effect will not affect depression symptoms for days or weeks
Mechanism of MAOIs
- NE and 5HT are normally degraded by monoamine oxidase
- increased amount of NE and 5HT packaged in vesicles because inhibiting monoamine oxidase
- causes depolarization and release, so we have more monoamines to activate pre and post synaptic receptors
- MAO -A breaks down 5HT & NE
- MAO-B breaks down dopamine
MAO inhibitors (drugs)
Non-selective: (irreversible)
- Phenelzine (nardil)
- Tranylcypromine (parnate)
MAO-B selective: (reversible)
- selegiline
MAO-A selective: (reversible)
- moclobemide (manerix)
MAOIs pearls
- Severe side effects: headache, drowsiness, dry mouth, weight gain, orthostatic hypotension, sexual dysfunction
- hypertensive crisis
- interactions with: TCAs, SSRIs, L-DOPA, cold preparations, diet pills
- avoid foods with Tyramine (ex. cheese, sour cream, liver, sausage, pepperoni, avocados, bananas, figs, soy sauce, ginseng)
- avoid St. John’s wort with MAOIs bc of its MAOI activity
Tricyclic antidepressants
Intication: depression, panic disorder, chronic pain, enuresis
overdose/toxicity: depressed patients more likely to be suicidal (bc have enough energy from drugs before therapy ‘kicks in’ so often self harm)
Tertiary Amines (TCA)
- 1st class of TCAs
- inhibit NE and 5HT reuptake via NET and SERT
- antihistamine, antimuscarinic, antiadrenergic activity
- SE: sedation, autonomic SE, weight gain
Drugs:
- imipramine (tofranil) - metabolized to desipramine - for enuresis and ADHD
- amitriptyline (elavil) - metabolized to nortriptyline
- clomipramine - used of OCD
- doxepin
Secondary Amines (TCA)
- 2nd class of TCAs
- better NET inhibitors than SERT
- SE: less sedation, anticholinergic, autonomic, weight gain, cardiovasular effects than tertiary amines
Drugs:
- desipramine (norpramin)
- nortriptyline (pamelor)
- maprotiline (ludiomil)
SSRI mechanism
- Seretonin transporters pumps are blocked, which increases the amount of 5HT in the synapse, 5HT stays in the synapse longer and remains active longer
- uses: depression, alcoholism, OCD, enuresis, PTSD, eating disorders, social phobias, panic, PMDD, GAD
- SE: N/V, headache, sexual dysfunction, anxiety, insomnia, tremor
SSRI drugs
- fluoxetine (prozac)
- fluvoxamine (luvox)
- paroxetine (paxil)
- sertraline (zoloft)
- citalopram (celexa)
- escitalopram oxalate (lexapro)
SSRI discontinuation syndrome
“brain zaps”. dizziness, sweating, nausea, insomnia, tremor, confusion, vertigo
Serotonin syndrome
when given with MAOIs, TCAs
- also metoclopramide, tramadol, triptans, st john’s wort
- symptoms: hyperthermia, muscle rigidity, restlessness, myoclonus, sweating, shivering, seizures
- treatment: discontinuation of medication and management of symptoms, serotonin antagonists, BZDs to control myoclonus
SSRI + 5HT1A partial agonists
vilazodone (viibryd)
-reduced sexual SE vs pure SSRIs
-similat 5HT1A action to aripiprazole and buspirone
votrioxetine (brintellex)
Tetracyclic and Unicyclic
- maprotiline (ludiomil) - NET inhibitor
- amoxapine (ascendin) - NET inhibitor, D2 antagonist
- mirtazapine (remeron) - a2 antagonist, 5HT2 & 5HT3 antagonist, H1 antagonish
- bupropion (wellbutrin) - DAT inhibitor, NET & SERT inhibitor, also treats GAD, Zyban for smoking cessation
SNRIs
Venlafaxine (effexor)
- NET & SERT inhibitors
- treats GAD and panic disorder
Desvenlafaxine (pristiq)
- NET & SERT inhibitor
- treatment of vasomotor symptoms associated with menopause
duloxetine (cymbalta)
- NET & SERT inhibitor
- treats GAD and peripheral neuropathy
milnacipran (ixel)
- NET & SERT inhibitor
- approved for fibromayalgia
levomilnacipran (fetzima)
-active enantiomer of milnacipran
-NET & SERT inhibitors
Norepinephrine selective reuptake inhibitors
reboxetine (vestra, edornax)
-possibly less side effects than prozac
atomoxetine (straterra)
-used for ADHD
Serotonin-Norepinephrine-Dopamine Reuptake Inhibitors (SNDRIs)
- “triple blockers”