Duloxetine (Cymbalta)
Duloxetine is a medication used by rheumatologists to treat different types of pain such as neuropathic pain and fibromyalgia.
Duloxetine is best known as an anti-depressant and for its various applications in psychiatry.
Duloxetine belongs to a class of medications called serotonin-norepinephrine reuptake inhibitors (SNRIs).
Taking Duloxetine
Duloxetine comes in different strength capsules. A typical starting dose is 30 to 60 mg taken once a day.
Important Tests and Risks
Patients who take Duloxetine should get occasional blood tests as requested by their doctor. It is important make sure Duloxetine isn’t irritating the liver.
Drinking alcohol while taking Duloxetine is not recommended because it can irritate the liver. Patients are advised to avoid alcohol completely, or at the very least, substantially limit the amount of alcohol that they drink.
If a patient needs to stop taking Duloxetine, this is best done slowly over a week or two. Patients should coordinate with their doctor if they want to stop taking this medication.
Science
Duloxetine is a serotonin-norepinephrine reuptake inhibitor, or SNRI. Serotonin and norepinephrine are two natural neurotransmitters that coordinate signals in the brain and other parts of the nervous system. They are known to affect mood and are believed to be involved in controlling the experience of pain.
After serotonin and norepinephrine are released by neurons (cells in the brain and nerves) to help transmit a signal, they re-enter cells in a process called reuptake where they are stored and are no longer active.
As a reuptake inhibitor, Duloxetine blocks this process and thus increases the levels of free serotonin and norepinephrine in the body, where they continue to play an active role in the transmission of nerve signals.
Increased levels of these neurotransmitters has found to be beneficial in patients suffering from types of depression and anxiety, and has also been shown to improve the symptoms of pain experienced by patients with fibromyalgia and other types of neurologic pain.
Scientists aren’t sure exactly how Duloxetine helps make fibromyalgia and neurologic pain feel better, but these conditions are not very well understood either!
Scientists think that this type of pain is due to changes in the nervous system that cause too many signals to fire off along pain pathways. It is thought that the increased levels of serotonin and norepinephrine caused by Duloxetine work to calm down these signals. The result is a reduction in pain experienced by the patient.
Safety
Nausea, drowsiness, insomnia, and dizziness are the most common side effects of Duloxetine.
Duloxetine can irritate the liver. Occasional blood tests help doctors monitor for this. Patients are advised to avoid alcohol to avoid irritating the liver and minimize the risk of this side effect.
Other possible side effects include:
- Nausea & Constipation – Duloxetine can cause pain in the stomach, nausea, or vomiting. It can also cause dry mouth and constipation
- Dizziness & confusion – Duloxetine can make people feel dizzy. It can rarely cause agitation or confusion.
- Blurry vision – Duloxetine can cause blurry vision. Patients should tell their doctor if they have glaucoma before starting this medicine.
- Blood pressure – Duloxetine can rarely cause an increase in blood pressure. Doctors will monitor this. Patients should tell their doctor if they have high blood pressure.
- Increased sweating – Duloxetine can rarely cause an abnormal increase in sweating.
- Headache – Duloxetine can rarely cause a headache.
- Bladder problems – Duloxetine can cause urine retention and difficulty voiding.
Duloxetine has not been studied in pregnancy. Patients should let their doctor know if they are planning to get pregnant or if they are breastfeeding.
People that should NOT take Duloxetine include:
- Patients with liver disease
- Patients who have alcohol abuse problems
Patients who want to stop taking Duloxetine should talk to their doctor. It is best to stop taking this medicine slowly.
People taking Duloxetine should call their doctor if they feel sick and want to stop, or if they are concerned about any side effects.
Other reasons for patients taking Duloxetine to call a doctor include:
- Dizziness, confusion, or agitation
- Blurry vision
- Increased blood pressure
- Severe stomach pain
- Pregnancy or planning pregnancy
Video
Watch Dr. Andy Thompson, a Canadian rheumatologist, introduce Duloxetine in this short video: