When to use them?
Antidepressants are used to treat disorders of mood (Unipolar and Bipolar depression, organic mood disorders, schizoaffective), anxiety disorders (panic disorder, generalized anxiety disorder, obsessive-compulsive disorder, and social phobia), impulse control and eating disorders.
Which antidepressant to use?
There are several classes of antidepressants with several drugs in each class. The specific drug you use will depend on the patient’s side-effect profile and other medical problems and the efficacy of the drug for that specific patient. It can take several weeks for the antidepressant to show improvement in mood.
-Dosage can be increase or the drug can be augmented with another drug (such as Lithium) if improvement is not seen.
-Overdose risk highest in Bupropion and TCAs.
Side-effects:
-include antichoinergic, antihistaminergic, hypotension, sedation, discontinuation syndrome (sudden cessation of SSRIs)
-Tricyclic Antidepressants can cause prolonged QT interval.
-MAOIs can cause hypo or hypertension and can cause a hypertensive crisis if ingested with tyramine containing foods, Serotonergic drugs, other drugs.
Discontinuation or serotonin syndrome:
(especially with MAOIs): initially, will be lethargic, restless, confused, sweaty, tremors, myoclonic jerks. Later on, can progress to hyperthermia, hypertonicity, renal failure, rhabdomyolysis, coma, death.
What to do? Should stop meds and give patient cyprohepatidine (Periactin).
Antidepressant Medications:
I. SSRI: inhibit presynaptic serotonin pumps to prevent serotonin reuptake.
a. Fluoxetine (Prozac) — has very long half-life and significant protein binding.
b. Citalopram (Celexa) – few interactions with other drugs
c. Escitalopram (Lexapro) – similar to citalopram but less side-effects
d. Paroxetine (Paxil) – used in maintenance treatment of panic disorders. Is more serotonin specific but has significant protein binding. Anticholinergic symptoms.
e. Sertraline (Zoloft) – used in maintenance treatment of panic disorders. Good for brain-injured patients (increased dopamine which is good for rehabilitation).
I. Side-effects: NOT as sedating:
1. sexual side-effects
2. problems with GI tolerability
3. Protein binding, shot-half life à SSRI discontinuation symptoms if stop for 3-4 half lives.
f. Fluvoxamine (Luvox)– used for OCD
II. SNRI: inhibit reuptake of serotonin and norepinephrine:
a. Venlafaxine (Effexor): for a tired, apathetic depressed patient. Very stimulating at first. Will prevent reuptake of dopamine at higher doses
b. Side-effects: hypertension, GI upset.
c. Lowest protein body, little drug interactions
d. Duloxetine (Cymbalta): for major depression and diabetic neuropathic pain.
e. Side-effects: Fatigue, sexual side-effects, serotonin discontinuation, GI upset.
III. NDRI:
a. Bupropion (Wellbutrin) – Used to help in smoking cessation. Usesful for apathetic, amotivational, inattentive depressive patients.
i. Side-effects: Decreases seizure threshold, can cause electrolyte abnormalities.
IV. SARI:
a. Nefazodone (Serzone): good for anxious-depressed patients.
i. Side-effects: 3A3/4 inhibition, sedation,
b. Desyrel (Trazodone): rarely used for treating depression but can be used in low doses for treating insomnia.
i. Side-effects: priapism
V. NaSSA: (noradrenergic and selective serotonin antidepressants) – block a2 receptors presynaptically (feedback) to inhibit release of norepinephrine and serotonin.
a. Mirtazapine (Remeron) – only anti-depressant that comes in orally-dissolving tablet.
i. Side-effects: increased appetite, weight gain, sedating.
VI. TCA: inhibit reuptake of norepinephrine and serotonin; can cause prolonged QT interval and are very sedating:
a. Imipramine (Tofranil) – used for enuresis, bed-wetting
b. Amitryptiline (Elavil) – used in lower doses for pain management
c. Trimipramine (Surmontil)
d. Nortriptyline (Pamelor)
e. Desipramine (Norpramin)
f. Clomipramine (Anafranil) – most serotonin specific. Used for OCD.
g. Amoxapine (Asendin)
h. Sinequan
VII. MAOI: Inhibits the enzyme that metabolizes norepinephrine, serotonin, dopamine, and tyramine. Results in increased neurotransmitters in the synapse.
a. Selegiline (Emsam)
b. Phenelzine (Nardil)
c. Tranylcypromine (Parnate)