Antidepressants

Antidepressants

What are Antidepressants?

Several drugs that were originally effective in treating depression can also be used to treat chronic pain.

• Not all antidepressants work to treat pain.
• Antidepressants that treat pain are not treating depression.
  • Antidepressants can help people to feel less pain regardless of whether they have depression.
  • People who have chronic pain and do not have depression are just as likely to feel improvement when they take antidepressants as the people who do have depression.
• These drugs can also be used to treat depression and anxiety.

How do Antidepressants work?

The antidepressants that are most useful in treating chronic pain are the ones that raise levels of two different brain chemicals or neurotransmitters – serotonin and norepinephrine.

• Antidepressants that mainly increase serotonin are called Selective Serotonin Reuptake Inhibitors (SSRIs).
• The antidepressants that increase both serotonin and norepinephrine are called Serotonin Norepinephrine Reuptake Inhibitors (SNRIs).
• The SNRI drugs that increase both serotonin and norepinephrine are often better at treating pain than the SSRI drugs that only increase serotonin.

These drugs work to treat pain by increasing serotonin and norepinephrine levels. This changes how the brain interprets pain.

• The brain is more sensitive to pain when levels of serotonin and norepinephrine are low in certain brain regions.
• Depression or anxiety is caused from having low serotonin and/or norepinephrine in other brain regions.
• The same drug can be used to treat pain as well as depression and anxiety.
  • This is because serotonin and norepinephrine impact all of these conditions.
• Even though drugs in this class are labelled as antidepressants, they work to improve pain and mood separately.
• Antidepressants do not improve pain by making depression better.

What are the names of some Antidepressants that are used to treat chronic pain?

SSRIs

• Fluoxetine (Prozac)
• Paroxetine (Paxil)
• Sertraline (Zoloft)
• Citalopram (Celexa)
• Escitalopram (Lexapro)
• Fluvoxamine (Luvox)
• Volazodone (Viibrid)
• Vortioxetine (Brintellix)

SNRIs

• Duloxetine (Cymbalta, Irenka).
  • This antidepressant has the best evidence for treating many types of chronic pain (e.g., neuropathic pain, fibromyalgia, osteoarthritis, low back pain).
• Milnacipran (Savella).
  • This drug is approved for use in fibromyalgia.
• Venlafaxine (Effexor, Effexor XR)
• Atomoxetine (Strattera)
• Desvenlafaxine (Pristiq, Khedezla)
• Levomilnacipran (Fetzima)
• Tramadol (Ultram, Ultracet)

Risks

Some of the more common side effects of antidepressants include:

• These side effects are usually worst when the person first starts taking the drug:
  • Nausea, vomiting, constipation, diarrhea, stomach pain, upset stomach, or feeling less hungry.
    • These side effects usually get better after taking the medicine for few days or weeks.
    • These side effects are often improved by taking the drugs with food.
• Other side effects:
  • Headache
  • Dry mouth
  • Trouble sleeping
  • Feeling dizzy, sleepy, tired, or weak
  • Sweating a lot
  • Weight change (both gain or loss)
  • Problems with sex

Some less common but more serious side effects of antidepressants include:

• Increased risk of suicide.
  • Drugs like these may increase the chance of suicidal thoughts or actions in children and young adults.
  • The risk may be greater in people who have had these thoughts or actions in the past.
  • All people who take antidepressants need to be watched closely – especially when they first start taking these drugs.
  • Call the doctor right away if signs like low mood (depression), nervousness, restlessness, grouchiness, panic attacks, or changes in mood or actions are new or worse.
  • Call the doctor right away if any thoughts or actions of suicide occur.
• Allergic reactions. Several different types of serious allergic reactions can occur in response to these drugs.
• Serotonin syndrome is a rare but very serious syndrome associated with taking drugs that increase serotonin.
• Symptoms include agitation, confusion, changes in balance, flushing, palpitations, shivering or shaking, fever, headache and even seizures.