duloxetine
Meaning of duloxetine: One drug licensed across mood and pain, duloxetine works partly through spinal cord pathways that damp pain signals before they reach the brain.
Definition of duloxetine
Duloxetine is a serotonin and norepinephrine reuptake inhibitor, a medicine that raises the amount of both messengers available between nerve cells. It is used for depression and generalized anxiety, and separately for several long lasting pain conditions, including the nerve pain of diabetes, fibromyalgia and chronic musculoskeletal pain, where the benefit does not depend on treating low mood.
What is it used for?
| Condition | Notes |
|---|---|
| Major depression | The original approved use |
| Generalized anxiety disorder | Approved in many countries |
| Diabetic peripheral neuropathy | Pain, burning, numbness or weakness, usually starting in the feet |
| Fibromyalgia | Widespread pain with fatigue and disturbed sleep |
| Chronic musculoskeletal pain | Includes long lasting low back pain and osteoarthritis pain |
| Stress urinary incontinence | Approved in some countries and not in others |
Being prescribed duloxetine therefore says nothing on its own about which of these is being treated. A person with diabetes taking it for nerve pain and a person taking it for depression are on the same drug for unrelated reasons.
How can one drug do both?
Serotonin and norepinephrine serve more than one system. In circuits regulating mood, raising their levels between nerve cells is associated over several weeks with lifting depression. Separately, a set of pathways runs downward from the brainstem into the spinal cord and damps pain signals before they travel upward, and those pathways use the same two messengers. Increasing their availability strengthens that braking action, which is the likelier explanation for the effect on pain. Two observations support it: the pain effect appears in people whose mood was never low, and it often appears sooner than any change in mood. The drug does not repair damaged nerves. It lowers how loudly they report.
How does it differ from an SSRI?
An SSRI acts almost entirely on the serotonin transporter. Duloxetine blocks the norepinephrine transporter as well, which is what places it in the SNRI group and underlies its use in pain, since the norepinephrine arm carries much of that effect. The wider action brings its own pattern of unwanted effects: nausea early on, dry mouth, disturbed sleep, sweating, and a rise in blood pressure in some people, which is watched because the norepinephrine effect reaches the circulation as well as the nervous system. Stopping abruptly can produce discontinuation symptoms, among them dizziness, irritability and brief sensations often described as electric shocks. Neuropathy caused by certain anticancer drugs has also been studied as a use and remains under investigation.
Also known as
Used in a sentence
Duloxetine was prescribed for the patient's diabetic peripheral neuropathy in addition to her depression.
Good to know
Duloxetine acts on both serotonin and norepinephrine, which separates it from antidepressants acting on serotonin alone and accounts for its established use in several pain conditions independent of any effect on mood.