How Do Fibromyalgia Agents Work?

Fibromyalgia agents are medications prescribed to treat fibromyalgia, a condition that causes chronic widespread pain, with associated symptoms such as fatigue, sleep and memory problems, anxiety, and depression. Fibromyalgia agents are also used to treat other painful conditions such as diabetic neuropathy and postherpetic neuralgia.

Fibromyalgia is thought to be caused by a chemical imbalance in the brain and dysfunctional neurotransmission resulting in low pain threshold and abnormal pain perception. Fibromyalgia agents reduce the symptoms of fibromyalgia by restoring the brain's chemical balance and preventing abnormal electrical activity in the brain.

Primarily, two classes of medications are used as fibromyalgia agents:

Serotonin-norepinephrine reuptake inhibitors (SNRIs)

SNRIs are antidepressant medications used to treat depression. SNRIs raise the levels of serotonin and norepinephrine by preventing their reabsorption (reuptake), a natural process in the brain. Serotonin and norepinephrine are chemicals (neurotransmitters) released by nerve cells (neurons) in the brain to transmit nerve signals.

Serotonin and norepinephrine play important roles in mood regulation and pain modulation. An increase in serotonin and norepinephrine levels improves mood and increases energy, and regulation of their activity alters pain perception and pain threshold.

Gamma-aminobutyric acid (GABA) analogs

GABA analogs are synthetic derivatives of GABA, a natural inhibitory neurotransmitter in the brain. GABA analogs do not affect the levels of GABA but block the inflow of calcium ions into nerve cells (neurons), which prevents the conduction of abnormal electrical impulses that transmit pain signals and/or cause seizure activity.

Fibromyalgia agents are oral tablets, capsules, or solutions approved by the FDA for the treatment of the following conditions:

• Fibromyalgia
• Diabetic peripheral neuropathic pain
• Postherpetic neuralgia
• Chronic musculoskeletal pain
• Neuropathic pain with spinal cord injury
• Partial onset seizures
• Major depressive disorder
• Generalized anxiety disorder
• Social anxiety disorder

Side effects of fibromyalgia agents may include the following:

• Nausea
• Xerostomia (dry mouth)
• Dizziness
• Somnolence (drowsiness)
• Headache
• Insomnia
• Constipation
• Fatigue
• Hot flush
• Peripheral edema
• Ataxia (difficulty with balance, coordination, and speech)
• Weight gain
• Tremor
• Dystonia (involuntary muscle contractions)
• Blurred vision
• Diplopia (double vision)
• Uveitis (inflammation of the uvea, a layer in the eye)
• Accommodation disorder (difficulty in eye focus)
• Dry eyes
• Visual impairment
• Glaucoma (a condition with high intraocular pressure that damages the optic nerve)
• Tinnitus (ringing in the ears)
• Ear pain
• Vertigo
• Balance disorder
• Joint swelling
• Nasopharyngitis (inflammation of the nasal passage and pharynx)
• An increase in liver enzymes ALT and AST
• Diarrhea
• Vomiting
• Reduced appetite
• Anorexia (loss of appetite)
• Weight loss
• Abdominal pain
• Dyspepsia (indigestion)
• Gastritis
• Colitis (inflammation of the colon)
• Gastroenteritis (infection and inflammation of the digestive system)
• Acute pancreatitis (inflammation of the pancreas)
• Hepatitis (inflammation of the liver)
• Neuropathy
• Musculoskeletal stiffness and pain
• Muscle spasms and twitching
• Trismus (lockjaw)
• Generalized pain
• Migraine
• Asthenia (physical weakness and lack of energy)
• Tremor
• Paresthesia (prickling sensation)
• Hypoesthesia (reduced sensation)
• Loss of consciousness
• Parkinsonism
• Convulsions
• Facial edema
• Hyperhidrosis (excessive sweating)
• Hypotension (low blood pressure)
• Hypertension (high blood pressure)
• Palpitations
• Tachycardia (rapid heartbeat)
• Supraventricular arrhythmia (irregular heartbeat that begins in the areas above the ventricles)
• Takotsubo cardiomyopathy (sudden weakness of the heart muscles)
• Heart failure
• Myocardial infarction (heart attack)
• Disorientation
• Poor quality sleep
• Abnormal dreams
• Hallucinations
• Delirium
• Abnormal thinking
• Agitation
• Aggression and anger
• Homicidal ideation
• Anxiety
• Confusion
• Amnesia (memory loss)
• Worsening depression
• Suicidal thoughts and behavior
• Withdrawal signs or symptoms
• Addiction
• Male sexual dysfunction
• Erectile dysfunction
• Decreased libido
• Abnormal orgasm
• Delayed or absent orgasm
• Delayed ejaculation
• Gynecomastia (breast enlargement in men or boys)
• Epididymitis (inflammation of epididymis, the coiled tube in the testicle that carries the sperm)
• Dysmenorrhea (menstrual cramps)
• Gynecologic bleeding
• Hirsutism (abnormal hair growth in women)
• Hyperprolactinemia (increase in prolactin levels)
• Galactorrhea (abnormal milk production and leakage)
• Hypothyroidism
• Hyperglycemia (increased glucose in the blood)
• Viral infection
• Upper respiratory tract infection
• Laryngitis (inflammation of the larynx)
• Pneumonia
• Respiratory depression
• Esophagitis (inflammation of the esophagus)
• Cough
• Influenza
• Oropharyngeal pain (oral and throat pain)
• Yawning
• Bruxism (teeth grinding)
• Dysgeusia (taste disorders)
• Chills
• Malaise
• Thirst
• Feeling hot or cold
• Cold sweat
• Night sweats
• Dysuria (painful urination)
• Acute renal failure
• Hypersensitivity reactions such as:
  • Rash
  • Urticaria (hives)
  • Pruritus (itching)
  • Erythema (redness of the skin)
  • Dermatitis
  • Photosensitivity
  • Erythema multiforme (round lesions like a bullseye)
  • Bullous pemphigoid (an autoimmune skin condition with blistering, hives, and itching)
  • Angioedema (swelling in the tissue under the skin or mucous membranes)
  • Stevens-Johnson syndrome (a rare medical emergency with flu-like symptoms and a painful rash)
  • Anaphylaxis (severe allergic reaction)
• Increased tendency to bruise
• Cutaneous vasculitis (inflammation of blood vessels in the skin)
• Abnormal bleeding
• Blood disorders such as:
  • Neutropenia (low count of neutrophils, type of immune cells)
  • Leukopenia (low count of leukocytes, type of immune cells)
  • Thrombocytopenia (low platelet count)
  • Anemia (low red blood cell count)
• Abnormal creatinine kinase
• Increase in cholesterol levels
• Hyponatremia (low sodium in the blood)
• Restless leg syndrome
• Aggression and anger after discontinuance of treatment
• Seizures on discontinuance of treatment
• Extrapyramidal disorders (movement disorders)
• Accidental injury
• Serotonin syndrome
• Rhabdomyolysis (breakdown of skeletal muscle cells)

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

Generic and brand names of fibromyalgia agents include:

• Cymbalta
• Drizalma Sprinkle
• duloxetine
• Irenka
• Lyrica
• Lyrica CR
• milnacipran
• pregabalin
• Savella