How Do SNRI Antidepressants Work?

Serotonin-norepinephrinereuptakeinhibitor (SNRI)antidepressantsare medications prescribed to treatdepressionand conditions such asfibromyalgia, which causechronicwidespreadpain. SNRIs increase the levels of serotonin and norepinephrine and regulate their activity.

Serotonin and norepinephrine are chemicals (neurotransmitters) released bynervecells (neurons)inthebrainto transmit nerve signals. Serotonin and norepinephrine play important roles in mood regulation and pain modulation, and abnormality in their functioning can causechronic pain,fatigue, depression, andanxiety.

SNRI antidepressants raise the levels of serotonin and norepinephrine by preventing theirreabsorption(reuptake), a naturalprocessin the brain. An increase in serotonin and norepinephrine levels improves mood and increases energy, and regulation of their activity alters pain perception and pain threshold.

SNRI antidepressants areoraltablets or capsules approved by theFDAfor the treatment of the following conditions:

• Majordepressive disorder
• Generalized anxiety disorder
• Social anxiety disorder
• Panic disorder
• 纤维肌痛症
• Diabeticperipheralneuropathic pain
• Chronic musculoskeletal pain

Off-label uses include:

• Hot flashesdue to hormonalchemotherapy
• Posttraumaticstressdisorder (PTSD)
• Attention deficit hyperactivity disorder(ADHD)
• Neuropathic pain

Side effects of SNRI antidepressants may include the following:

• Nausea
• Dry mouth
• Hyperhidrosis(excessivesweating)
• Dizziness
• Insomnia
• Constipation
• Somnolence(drowsiness)
• Headache
• Fatigue
• Hotflush
• Asthenia(weakness)
• Anorexia(loss of appetite)
• Diarrhea
• Vomiting
• Dyspepsia(indigestion)
• Abdominal pain
• Gastritis
• Flatulence
• Ejaculationdisorder
• Anorgasmia(difficulty reachingorgasm)
• Decreasedlibido
• Sexualdysfunction
• Erectile dysfunction
• Testicular pain
• Impotence
• Increase incholesterollevels
• Increase intriglycerides
• Nervousness
• Agitation
• Mood swings
• Tremor
• Vertigo
• Anxiety
• Poor qualitysleep
• Abnormaldreams
• Depersonalization
• Hallucinations
• Activation ofmaniaorhypomania
• Seizure
• Delirium
• Loss of consciousness
• Suicideideation and attempt
• Homicidal ideation
• Mydriasis(dilationof pupils)
• Blurred vision
• Diplopia(double vision)
• Abnormal vision
• Accommodationdisorder (difficulty ineyefocus)
• Dry eyes
• Visual impairment
• Narrow-angleglaucoma(aconditionwith highintraocular pressurethat damages theoptic nerve)
• Musculoskeletal stiffness and pain
• Musclespasm
• Twitching
• Paresthesia(pricklingsensation)
• Hypoesthesia (reduced sensation)
• Parkinsonism
• Impaired coordination andbalance
• Convulsions
• Catatonia (inability to move normally)
• Dystonia(involuntarymuscle contractions)
• Trismus(lockjaw)
• Vasodilation
• Syncope(晕倒)
• Bruxism(teeth grinding)
• Tinnitus
• Earpain
• Dysgeusia(tastedisorders)
• Migraine
• Chills
• Yawning
• Thirst
• Malaise
• Throatpain
• Nasopharyngitis (inflammationofnasal passageandpharynx)
• Laryngitis(inflammation of thelarynx)
• Upperrespiratorytractinfection
• Cough
• Influenza
• Interstitiallungdiseaseand eosinophilicpneumonia
• Dyspnea(shortness of breath)
• Palpitations
• Supraventriculararrhythmia(irregular heartbeat that begins in the areas above theventricles)
• Tachycardia(rapid heartbeat)
• Hypertension(high blood pressure)
• Hypotension(low blood pressure)
• Ischemiccardiacevents in people with cardiac risk factors
• Myocardial infarction(heart attack)
• Takotsubo cardiomyopathy(sudden weakness of theheartmuscles)
• Weight gain
• Weight loss
• Colitis(inflammation of thecolon)
• Pancreatitis(inflammation of thepancreas)
• Hepatitis(inflammation of theliver)
• Gastroenteritis(infection and inflammation of thedigestive system)
• Abnormal liver function test results
• Hyperprolactinemia (increase inprolactinlevels)
• Galactorrhea(abnormal milk production and leakage)
• Gynecologic bleeding
• Hypothyroidism
• Hyperglycemia(increasedglucosein theblood)
• Urinaryretention
• Dysuria(painful urination)
• Anuria (lack ofurineoutput)
• 急性肾功能衰竭
• Hypersensitivity reactions such as:
  • Rash
  • Urticaria(hives)
  • Pruritus(itching)
  • Dermatitis
  • Alopecia(hair loss)
  • Photosensitivity
  • Erythema multiforme(roundlesions like a bullseye)
  • Angioedema(swelling in thetissueunder theskinormucousmembranes)
  • Stevens-Johnson syndrome(a rare medical emergency withflu-like symptoms and a painful rash)
  • Toxicepidermalnecrolysis (a severe skin condition with widespread redness, skincelldeath, and exfoliation which can lead tosepsis)
  • Anaphylaxis(severeallergic reaction)
• Increased tendency tobruise
• Cutaneousvasculitis(inflammation of blood vessels in the skin)
• Reduced blood cell count conditions such as:
  • Neutropenia(low neutrophils, a type ofimmunecell)
  • Leukopenia(lowleukocytes, a type of immune cell)
  • Agranulocytosis(lowgranulocytes, immune cells with granules)
  • Thrombocytopenia(lowplatelet count)
  • Anemia
• Hyponatremia(lowsodiumin the blood)
• 动脉瘤(weakened area and bulging in the bloodvessel)
• Deepveinthrombophlebitis(blood clotin the vein with inflammation)
• Bacteremia(bacterialinfection in the blood)
• Gastrointestinalbleeding
• Abnormal bleeding
• Serotoninsyndrome
• Drug discontinuance symptoms
• Restless leg syndrome
• Aggression andangerafter treatment discontinuation
• Seizures on discontinuance of treatment
• Extrapyramidal disorders (movement disorders)
• Rhabdomyolysis(breakdown ofskeletal musclecells)

Information contained herein is not intended to cover all possible side effects, precautions, warnings, drug interactions, allergic reactions, or adverse effects. Check with yourdoctoror药剂师to make sure these drugs do not cause any harm when you take them along with other medicines. Never stop taking yourmedicationand never change your dose or frequency without consulting your doctor.

Genericand brand names of SNRIantidepressantdrugs include:

• Cymbalta
• desvenlafaxine
• Drizalma Sprinkle
• duloxetine
• Effexor XR
• Fetzima
• levomilnacipran
• milnacipran
• Pristiq
• Savella
• venlafaxine