Euphorbia resinifera, the resin spurge, is a species of spurge native to Morocco, where it occurs on the slopes of the Atlas Mountains. The dried latex of the plant has been used as ancient medicine. It contains resiniferatoxin, a capsaicin analog tested as an analgesic since 1997.
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Euphorbia resinifera is a species of spurge native to Morocco, where it occurs on the slopes of the Atlas Mountains.<ref name="rhs">Template:Cite book</ref> It is similar to its relative Euphorbia echinus, which occurs on the Moroccan coast and the Canary Islands.
Euphorbia resinifera contains a milky fluid or latex, which in its dried form is called Euphorbium. It has high concentration of resiniferatoxin, an analog of capsaicin, the primary vanilloid compound found in hot peppers. It can interact with a vanilloid receptor on primary sensory neurons mediating pain (nociception) and neurogenic inflammation. The pain sensing cation channel is TRPV1.<ref name=life>Template:Cite journal</ref> Resiniferatoxin has been used as a starting point in the development of a novel class of analgesics. Desensitization to topical resiniferatoxin is tested in clinical trials to evaluate its potential to relieve neuropathic pain, as in diabetic polyneuropathy and postherpetic neuralgia.<ref name=life/> resiniferatoxin injected subcutaneously into a rat hind paw several minutes before a surgical incision reduced postsurgical pain for 10 days in a NIH study published March 2018.<ref>Stephen J. Raithel; Matthew R. Sapio; Danielle M. LaPaglia; Michael J. Iadarola; Andrew J. Mannes.Transcriptional Changes in Dorsal Spinal Cord Persist after Surgical Incision Despite Preemptive Analgesia with Peripheral Resiniferatoxin. Anesthesiology 3 2018, Vol.128, 620-635. doi:10.1097/ALN.0000000000002006</ref> It is tested to treat pain with advanced cancer.<ref>National Institute of Dental and Craniofacial Research Resiniferatoxin to Treat Severe Pain Associated With Advanced Cancer December 8, 2008, retrieved February 28, 2018</ref>
Resiniferatoxin was isolated in 1975.<ref name=life/> Euphorbium has been used since at least its first written record from the time of Roman Emperor Augustus.<ref name=life/>