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monoamine oxidase inhibitors
- irreversible: phenelzine, tranylcypromine
- reversible: moclobemide
- - well absorbed from GI, peak levels in 2-3 hrs, metab’d in liver (acetyl), excreted in urine
- - *precaution: hepatic or renal impairment, pregnancy and lactation
- - NOT 1st line: resistant depression.
- - SE: INODES
- - overdose: sx 12 hours after ingestion: tachy, circulatory collapse, sz, coma
- - tx of overdose: eliminate toxin via gastric lavage, urine acidification, hemodialysis
- - DI: TCA, sympathomimetics, SSRI/SNRI, meperidin, tyramine.
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TCAs for depression
- tricyclics: 2o: desi, nortrip (pref NE block). 3o: imip, amitrip, clomip, doxepin, trimip (pref 5-HT block)
- tetracyclic: maprotiline
- increasing NE selectivity: ami < imi < nor < maprotiline
- - well absorbed from GI, highly PB and lipid solub, peak levels in 2-3 hrs, metab’d in liver (acetyl), excreted in urine
- - *precaution: hepatic or renal impairment, pregnancy and lactation
- - depression, childhood enuresis (imipramine), OCD (clomipramine), adjunctive analgesics, trigeminal neuralgia
- - SE: antichol, antihist, antiadrenergic, sexual dysfxn, reduced sz threshold
- - overdose: lethal. tx: activated charcoa, urine alkalinization to speed elim, life support.
- - DI: MAOIs, barb/cbmz/rifampin induce enzymes, cimetidine/atipsychs inhibit enzymes, clonidine (dec'd anti-htn effects)
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SSRIs
- citalopram, fluoxetine, fluvoxamine, paroxetine, escitalopram, sertraline
- increasing 5-HT selectivity: clomipramine < fluoxetine < sertraline
- - selectively inhibit human serotonin transporter (hSERT) and cause increased 5-HTP concentrations at nerve endings.
- - little/no effect NE/DA
- - little/no CVS effects
- - 1st Choice AD because greater tolerability and ease of dosing.
- - CNS: h/a, sleep disturbance, dizziness, anorexia, tremor, nervousness
- - GI: N, D, C, dry mouth, GI bleeding
- - sweating
- - sexual dysfunction
- - DI: MAOIs, CYP450 inducers, CYP450 inhibitors.
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SNRIs for depression
- venlafaxine, desvenlafaxine, duloxetine
- - inhibit reuptake 5-HTP, NE, dose dependent.
- - low doses: SSRI
- - med doses: + NE block
- - high doses: + DA block
- - Use: depression, neuropathic pain, pain ass`d with fibromyalgia
- - SE: CNS: sleep disturb, insomnia, drowsiness, dizziness, nervousness
- - GI: nausea, dry mouth (Ach) at high doses
- - CVS: htn at high doses
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NE and DA reuptake inhibitors
- bupropion
- - antidepressant effects thru NE and DA reuptake inhib
- - blockade of DA uptake > NE uptake
- - sx of DA deficiency targeted: anhedonia, hypersomnia, cognitive slowing, inattention, craving
- - good sub for SSRI-induced sexual dysfunction
- - Use: depression, smoking, ADHD
- - SE: agitation, anorexia, insomnia, Sz (dose dependent)
- - CI: current Sz disorder, bulimia or anorexia nervosa (GABA changes inc risk of sz)
- - DI: MAOIs
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5-HT antagonist/reuptake inhibitor
- trazodone
- - potent blocker of post-synaptic serotonin receptors
- - weak serotonin reuptake blocker
- - Use: depression, hypnotic in depressed pts
- - SE: daytime sedation at tx doses
- - orthostatic hypo, N, h/a, priapism, dry mouth
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NE and specific 5-HT antidepressants
- mirtazapine
- - drug blocks central presyn alpha-2 adrenergic inhibitory autoreceptors
- - results in increased central NE and 5-HTP activity
- - Use: depression
- - SE: antihist (weight gain, sedation), antiadrenergic (orthostatic hypotension)
- - DI: MAOIs
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chronic antidepressant use:
- - desensitization of of post-synaptic receptors
- - block NMDA receptors (reduce glutamate activity), increase synthesis of microtubules (change signal transduction), enhance synth and transport of NT synthesizing enzymes (tyrosine and tryptophan hydroxylase)
- - normalize muscarinic supersensitivity
- - reduce proinflammatory cytokines and PGE2 (and normalize/increase central MA release)
- - reduces cortisol, increases BDNF (transcription factor) to increase neuronal plasticity and recovery (esp increase hippocampal volume)
- - sensitizes GC receptors on catecholamine and 5-HT cell bodies to normalize NE and 5-HT function (that is reduced by hypercortisolemia)
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