Antidepressants

Antidepressants are a class of drugs that reduce symptoms of depressive disorders by correcting chemical imbalances of neurotransmittersinthebrain．Chemical imbalances may be responsible for changes in mood and behavior.

Neurotransmitters arevital, as they are the communication link betweennervecells in the brain. Neurotransmitters reside withinvesiclesfound in nerve cells, which are released by one nerve and taken up by other nerves. Neurotransmitters not taken up by other nerves are taken up by the same nerves that released them. Thisprocessis called "reuptake．" The prevalent neurotransmitters in the brain specific todepressionareserotonin,dopamineand去甲肾上腺素(also called noradrenaline).

In general, antidepressants work by inhibiting the reuptake of specific neurotransmitters, hence increasing their levels around the nerves within the brain, such as selective serotonin reuptake inhibitors (SSRIs), antidepressants that willaffectserotonin levels in the brain.

Antidepressants are used to treat several conditions. They include, but are not limited to: depression,generalized anxiety disorder, agitation, obsessive compulsive disorders (OCD),manic-depressive disorders,childhoodenuresis(bedwetting),majordepressive disorder, diabeticperipheralneuropathic pain, neuropathicpain, socialanxietydisorder, posttraumaticstressdisorder (PTSD) etc.

Some off- label uses of antidepressants include, but are not limited to:fibromyalgia,chronicurticaria(hives),hot flashes,hyperhidrosis(药物),pruritus(itching),premenstrualsymptoms,bulimia nervosa,Tourette syndrome,binge eating disorder, etc.

Antidepressants differ in their effects on neurotransmitters, established uses, adverse effects and drug interactions. All antidepressants that are used for depression are effective; there is no evidence that oneantidepressantis more effective than another. However, patients may respond to or tolerate one antidepressant, and not respond to or tolerate another antidepressant.

Antidepressants that belong to the same class of antidepressant produce similar side effects. Antidepressants may causewithdrawal symptomsif abruptly discontinued. Withdrawal symptoms includenausea, vomiting,dizziness,headache, irritability,sleepdisturbance, nightmares,psychosis, and seizures. All antidepressants have a warning about use in children and adolescents. Antidepressants increased the risk ofsuicidalthinking, and suicidal behavior in short-term studies in children and adolescents with depression and otherpsychiatricdisorders. Anyone considering the use of antidepressant in a child or adolescent mustbalancethis risk ofsuicidewith theclinicalneed for the drug. Patients who are started ontherapyshould be closely observed for clinical worsening, suicidal thoughts or unusual changes in behavior.

Tricyclic antidepressants(TCAs) are a class of antidepressant associated with sedation,dry mouth,blurred vision,constipation,urinaryretention, and increased pressure in theeye．他们是肌萎缩性侧索硬化症o associated withhypertension,abnormalheartrhythms, anxiety,insomnia, seizures, headache,rash, nausea, and vomiting,abdominalcramps,weight loss, and sexualdysfunction．Tricyclic antidepressants rarely causeliver failure．

Selective serotonin reuptake inhibitors (SSRIs) and serotonin/norepinephrine reuptake inhibitors (SNRIs) are two classes of antidepressants associated with abnormal thinking, agitation, anxiety, dizziness, headache, insomnia, sexual dysfunction, sedation,tremor,sweating, weight loss,diarrhea, constipation, drymouth, rash, and nausea. Rarely, SSRIs have been associated withhyponatremia(lowsodium),hypoglycemia(lowblood glucose), and seizures.

Monoamine oxidase inhibitors (MAOIs) are a class of antidepressant associated withpostural hypotension(feeling faint upon standing due to decreasedbloodflow to the brain),high blood pressure,fainting, abnormal heart rhythm, dizziness, headache, drowsiness, insomnia, anxiety, constipation, nausea, diarrhea, sexual dysfunction, weight gain or weight loss, and水肿．Seizures, rash, blurred vision, andhepatitisare infrequently associated with MAOIs.

Combining tricyclic antidepressants (TCAs) withclonidine(Catapres) may lead to dangerous elevations inblood pressurebecause TCA may inhibit theantihypertensiveeffect of clonidine. Combining TCAs withcarbamazepine(Tegretol) may result in lower TCA blood levels and higher carbamazepine levels, leading to decreased TCA efficacy or increased carbamazepinetoxicity．TCAs may increase the effects ofepinephrine, norepinephrine and dopamine. Dangerous increases in blood pressure and abnormal heartbeats may occur.Cimetidine(Tagamet) may reduce the breakdown of some TCAs [for example,amitriptyline(Elavil)] and potentially lead to increased side effects.

Selective serotonin reuptake inhibitors (SSRIs) should not be combined with other drugs that increase brain serotonin levels [for example, MAOIs, TCAs,sumatriptan(Imitrex),linezolid(Zyvox),St John's Wort, amphetamines] because there is a risk of dangerous adverse effects. The risk ofgastrointestinalbleeding may be increased when SSRIs are combined with nonsteroidal antiinflammatory drugs (NSAIDs).

Monoamine oxidase inhibitors (MAOIs) should not be combined with other antidepressants or other drugs that increase serotonin levels [for example, amphetamines, linezolid (Zyvox), St. Johns Wort, sumatriptan (Imitrex)]. Such combinations cause excessive serotonin levels in the brain, which may lead to confusion, high blood pressure, tremor,hyperactivity,coma, anddeath．Administration of MAOIs and other antidepressants or drugs that elevate serotonin should be separated by 14 days. Administration of MAOIs with epinephrine, norepinephrine,phenylephrine,pseudoephedrine, and dopamine may lead tohypertensive crisis．MAOIs interact with tyramine containing foods, resulting in ahypertensivecrisis.

• amitriptyline (Elavil)
• amoxapine
• clomipramine(Anafranil)
• desipramine(Norpramin)
• doxepin(Sinequan)
• imipramine (Tofranil)
• maprotiline
• nortriptyline(Pamelor)
• protriptyline (Vivactil)
• trimipramine (Surmontil)

• citalopram(Celexa)
• escitalopram(Lexapro)
• fluoxetine(Prozac,Sarafem)
• fluvoxamine (Luvox)
• paroxetine(Paxil)
• sertraline(Zoloft)

• duloxetine(Cymbalta)
• venlafaxine(Effexor)
• desvenlafaxine (Pristiq)

• phenelzine (Nardil)
• tranylcypromine (Parnate)
• isocarboxazid (Marplan)
• selegiline(EMSAM,Eldepryl)

• Mirtazapine(Remeron)
• Desyrel(trazodone)
• Bupropion(Wellbutrin)
• nefazodone (Serzone)