Drug Classification of Duloxetine
Duloxetine is classified as a Serotonin-Norepinephrine Reuptake Inhibitor (SNRI), also referred to as a selective serotonin and norepinephrine reuptake inhibitor (SSNRI). 1
Mechanism of Action
Duloxetine inhibits the presynaptic reuptake of both serotonin and norepinephrine in the central nervous system, which is the defining characteristic of the SNRI drug class. 2, 1
The drug demonstrates approximately 10-fold selectivity for serotonin over norepinephrine reuptake, distinguishing it from other SNRIs like venlafaxine (30-fold selectivity for serotonin) and milnacipran (equal affinity for both). 3
Duloxetine is also a weak inhibitor of dopamine reuptake but has no significant affinity for other receptor systems including dopaminergic, adrenergic, cholinergic, histaminergic, opioid, or glutamate receptors. 1
It does not inhibit monoamine oxidase (MAO), which differentiates it from MAOIs as a separate drug class. 1
Official Classification Terminology
The SNRI class terminology varies slightly across sources:
The FDA drug label officially describes duloxetine as a "selective serotonin and norepinephrine reuptake inhibitor (SNRI)". 1
Some clinical guidelines use the term "selective serotonin norepinephrine reuptake inhibitor (SSNRI)" interchangeably with SNRI. 2
Both terms refer to the same drug class and mechanism of action. 2
SNRI Class Members
Currently marketed SNRIs in the United States include:
- Venlafaxine
- Desvenlafaxine
- Duloxetine
- Levomilnacipran 2
Important distinction: Atomoxetine is a selective norepinephrine reuptake inhibitor (not an SNRI) and should not be confused with the SNRI class despite sometimes being grouped with them. 2