BRIEF ANTIDEPRESSANT OVERVIEW Casey Gallimore, Pharm.D., M.S.
Antidepressant Medication Classes First Generation Tricyclic Antidepressants (TCAs) Monoamine Oxidase Inhibitors (MAOIs) Second Generation Selective Serotonin Reuptake Inhibitors (SSRIs) Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs) Norepinephrine-Dopamine Reuptake Inhibitors (NDRIs) Other
First Generation Antidepressants
Tricyclic Antidepressants (TCAs) Tertiary Amines Imipramine (Tofranil ) Amitriptyline (Elavil ) Demethylated Secondary Amines Desipramine (Norpramin ) Nortriptyline (Pamelor ) Clomipramine (Anafranil ) Doxepin (Silenor )
Mechanism of Action: TCAs Inhibits membrane pump mechanism responsible for the absorption of serotonin (5-HT) and norepinephrine (NE) in serotonergic and adrenergic neurons Block muscarinic M1, histamine H1, and alphaadrenergic receptors Amount of 5-HT and NE effects depends on the compound: Tertiary amines = 5-HT > NE reuptake inhibition Secondary amines = NE > 5-HT reuptake inhibition
TCA Adverse Effects Block muscarinic M1, histamine H1, and alpha-adrenergic receptors Cardiovascular arrhythmias, tachycardia, orthostatic hypotension Anticholinergic Sedation Neurologic Effects Weight Gain Dangerous in overdose!!! As Sexual Dysfunction little as 10 times the daily dose can be fatal.
Responsible receptors Tertiary Amines Muscarinic Histamine Alphaadrenergic Anticholinergic Drowsiness Weight Gain Hypotension QT prolongation 5-HT2 Sexual Dysfunction Amitriptyline ++ ++ ++ ++ ++ ++ Clomipramine ++ ++ ++ + + ++ Doxepin ++ ++ ++ + ++ ++ Imipramine ++ ++ ++ ++ ++ ++ Triimipramine ++ ++ ++ ++ + ++ Secondary Amines Desipramine + + + + ++ ++ Nortriptyline + + + + ++ ++ Protriptyline + + + + ++ ++ Miscellaneous Amoxapine + + + + + ++ Maprotiline + + + + ++ ++ ++ high risk, + moderate risk Adapted from UpToDate : Side Effects of Antidepressants (table)
Monoamine Oxidase Inhibitors (MAOIs) Phenelzine (Nardil ) Tranylcypromine (Parnate ) Selegiline (Emsam ) Mechanism of Action Irreversible inhibition of MAO-A & B, resulting in increased levels of 5HT, NE, and dopamine Phenelzine and tranylcypromine are non-selective inhibitors Selegiline inhibits MAO-A & B in the brain but has reduced effects in the gut (dose dependent)
MAOI Drug Interactions Inhibited metabolism of various monoamines including 5-HT, NE and tyramine can result in: Serotonin syndrome Concurrent serotonergic medications Hypertensive crisis Ingesting large amounts of tyramine or other vasoactive amines in foods or medications Clinical presentation acute onset of severe headache, nausea, neck stiffness, palpitations, profuse perspiration, and confusion can possibly lead to stroke and death
MAOI Drug Interactions Concomitant use contraindicated*: Other antidepressants Buspirone Dextromethorphan Sympathomimetic drugs (amphetamine, cocaine, methylphenidate, epinephrine, phenylephrine, etc) Start SSRI or other antidepressant 14 days after stopping MAOI 5 half life wash out of previous antidepressant before starting MAOI * This does not represent a comprehensive list of contraindications
MAOI Food Interactions (Tyramine Containing) Absolute Contraindications Aged cheeses, aged and cured meats, banana peel, sauerkraut, soy sauce, tap beer, marmite Moderate Contraindications red or white wine, bottled or canned beer Unnecessary avocados, bananas, chocolate, fresh and mild cheeses, fresh meat, MSG, peanuts, raspberries, soy milk
Second Generation Antidepressants
Selective Serotonin Reuptake Inhibitors (SSRIs) Citalopram (Celexa ) Escitalopram (Lexapro ) Fluoxetine (Prozac, Prozac Weekly, Sarafem ) Fluvoxamine (Luvox CR) Paroxetine (Paxil, Paxil CR ) Sertraline (Zoloft ) Vilazodone (Viibryd ) Vortioxetine (Trintellix )
Mechanism of Action: SSRIs Decreases the action of the presynaptic 5-HT reuptake pump which increases duration of 5-HT in the synapse and increases postsynaptic 5-HT receptor occupancy In addition, vilazodone is 5-HT 1A receptor partial agonist vortioxetine is 5-HT 1A agonist, 5-HT 1B partial agonist, and antagonist of 5-HT 3, 5-HT 1D and 5-HT 7 receptors
Serotonin Norepinephrine Reuptake Inhibitors (SNRIs) Venlafaxine (Effexor, Effexor XR ) Desvenlafaxine (Pristiq ) Duloxetine (Cymbalta ) Levomilnacipran (Fetzima ) Selectively inhibit neuronal reuptake of 5-HT and NE
SNRIs Venlafaxine predominately 5-HT effects until dose reaches 150-300mg per day Desvenlafaxine O-desmethyl metabolite of venlafaxine via CYP2D6 Duloxetine dual 5-HT and NE action along entire dosing spectrum Also FDA approved for diabetic peripheral neuropathy, fibromyalgia, chronic musculoskeletal pain Levomilnacipran greatest noradrenergic activity in vitro among available SNRIs
Norephinephrine Dopamine Reuptake Inhibitors (NDRIs) Bupropion (Wellbutrin, Wellbutrin SR, Wellbutrin XL ) Inhibits neuronal uptake of NE and dopamine Also FDA indication for smoking cessation (Zyban )
Other serotonin modulators Mirtazapine (Remeron ) Increases 5-HT and NE release by central presynaptic alpha2- adrenergic antagonist effects Potent antagonist of 5-HT2 and 5-HT3 serotonin receptors and H1 histamine receptors and a moderate peripheral alpha1-adrenergic and muscarinic antagonist Trazodone (Oleptro ) Increases serotonergic neurotransmission Blocks histamine (H1) and alpha1-adrenergic receptors Nefazodone (Serzone ) Antagonist of 5HT-2 receptors and 5-HT reuptake blocking
St. John s Wort Herbal product (Hypericum perforatum) Modulates neurotransmitter levels of 5-HT, NE, and dopamine most likely by inhibiting reuptake
Shared Adverse Effects Acute GI effects (upset, nausea, vomiting) Dizziness Headache Sedation / Insomnia Anxiety / jitteriness ** usually tolerate out after 1-4 weeks Chronic Sweating Tremor Vivid dreams Increased bleeding risk Hyponatremia Sexual dysfunction Worsening mood / suicide Serotonin syndrome
Fluoxetine Sertraline Citalopram & Escitalopram Fluvoxamine Paroxetine Vilazodone (Viibryd) Vortioxetine (Brintellix) -Longest t ½ (self-tapering) -CYP 2D6, 3A4, 2C inhibitor -Diarrhea as adverse effect -Risk of QT prolongation -Few drug-drug interactions -CYP 1A2, 3A4, 2C inhibitor -Often prescribed for OCD -Anticholinergic effects, most sedating, wt gain -Shortest t ½ (withdrawal) -CYP 2D6 inhibitor -SSRI + 5-HT1A receptor partial agonist -Lower risk of sexual dysfunction -SSRI + 5-HT1A agonist, 5-HT1B partial agonist, and antagonist of 5-HT3, 5-HT1D and 5-HT7 receptors -Main ADEs: GI related (nausea, vomiting, constipation)
Unique Attributes SNRIs Increased BP and HR (least potential with duloxetine, greatest with venlafaxine) GI effects (upset, N/V, constipation) slow taper, use venlafaxine XR formulation Levomilnacipran (Fetzima ) newest SNRI Bupropion Decreased appetite Restlessness, insomnia (dose earlier in day) Lowered seizure threshold (contraindicated with seizure disorder and eating disorders) Lower risk of sexual dysfunction
Unique Attributes Mirtazapine Weight gain Sedation More prominent at lower doses Dry mouth Constipation Lower risk of sexual dysfunction Trazodone Sedation Hypotension Priapism Low incidence of sexual side effects Nefazodone Hepatitis, liver failure 1 per 250,000 to 300,000 patient-years in US Lower risk of sexual dysfunction
Place in Therapy
First vs Second Generation Antidepressants Equivalent efficacy in treating depression and many anxiety disorders However, second generation agents generally preferred over first generation agents Fewer drug interactions Improved tolerability Greater safety profile
FDA-Labeled Indications Antidepressant MDD GAD SAD PD OCD PTSD BPD Citalopram X Escitalopram X X Fluoxetine X X X X Fluvoxamine X Paroxetine X X X X X X Sertraline X X X X X Vilazodone X Vortioxetine X Venlafaxine X X X X Desvenlafaxine X Duloxetine X X Levomilnacipran X Mirtazapine X Trazodone X Nefazodone X Bupropion X MDD=major depressive disorder, GAD=generalized anxiety disorder; SAD=social anxiety disorder, PD=panic disorder, OCD=obsessive compulsive disorder, PTSD=post traumatic stress disorder, BPD=bipolar disorder
Thank you for your attention! If you have any questions regarding this presentation feel free to email me at Casey.Gallimore@wisc.edu.