RESEARCH MONOGRAPH · KDC-MN-209
Duloxetine
Duloxetine (Cymbalta) is an SNRI from Eli Lilly, approved in 2004, that hits the serotonin and norepinephrine pumps in roughly balanced fashion across its dose range (unlike venlafaxine, which only becomes a true SNRI at higher doses). The norepinephrine half of the action turns out to be useful for chronic pain, because pain-modulating circuits in the spinal cord rely on norepinephrine signaling. That is why duloxetine carries FDA approvals not just for depression and generalized anxiety but also for diabetic neuropathy, fibromyalgia, and chronic musculoskeletal pain, an unusually broad label for an antidepressant. Liver enzyme effects are notable, particularly through CYP1A2 and CYP2D6. Discontinuation is rough but generally less severe than venlafaxine. Not stocked by Kodiac. This monograph is provided for research and educational reference.
Intrigue 0–100 blends mechanism novelty, evidence strength, and translational potential. Kodiac editorial, not peer-reviewed.
Serotonin-norepinephrine reuptake inhibitor
A balanced-affinity SNRI distinguished by approval for chronic pain and diabetic peripheral neuropathy in addition to depression.
Abstract
Duloxetine ((S)-N-methyl-3-(naphthalen-1-yloxy)-3-(thiophen-2-yl)propan-1-amine; CAS 116539-59-4; molecular formula C18H19NOS; molecular weight 297.41) is a balanced-affinity SNRI developed at Eli Lilly and approved by the FDA in 2004 under the trade name Cymbalta. SERT (Ki approximately 0.8 nM) and NET (Ki approximately 7.5 nM) affinities are both nanomolar, with a SERT/NET ratio of roughly 10, more balanced than venlafaxine (ratio approximately 30). The compound exhibits weak DAT inhibition (Ki approximately 240 nM) of marginal clinical relevance. Plasma half-life is approximately 12 hours; metabolism is via CYP1A2 (primary) and CYP2D6 (secondary). The compound is itself a moderate CYP2D6 inhibitor, producing relevant interactions with TCAs, antipsychotics, and tamoxifen. Approved indications include major depressive disorder, generalized anxiety disorder, fibromyalgia, diabetic peripheral neuropathic pain, and chronic musculoskeletal pain. The pain indications reflect the noradrenergic component's role in descending pain modulation. Used as the canonical balanced SNRI in mechanism studies and as a reference compound for descending pain modulation research.
Mechanism of action
Balanced SERT/NET inhibition with weak DAT inhibition. Noradrenergic component mediates analgesic effects via descending pain modulation.
Reported research dose ranges
Reported research dose ranges in the literature.
References
- Bymaster FP, et al. Comparative affinity of duloxetine and venlafaxine for serotonin and norepinephrine transporters. Neuropsychopharmacology 2001.
- Wernicke JF, et al. The clinical pharmacokinetic profile of duloxetine. Hum Psychopharmacol 2008.
- Smith HS, et al. Duloxetine in the management of chronic musculoskeletal pain. Ther Clin Risk Manag 2012.
Read the full monograph
Available as a research-use-only PDF download. Note: PDFs for newly added compounds may take a few hours to propagate after this article was published.
The full reference document is provided strictly for research use only. It reports research dose ranges from the published literature, not instructions for use in humans or animals.
FOR RESEARCH USE ONLY. Not for medical, diagnostic, or therapeutic purposes. Not for human consumption. All information is provided for research and educational purposes only.