Analgesic and opioid-like effects of Kratom

"In Southeast Asia, kratom has long been used for the management of pain and opium withdrawal.^6,9-11,14 In the West, kratom is increasingly being used by individuals for the self-management of pain or withdrawal from opioid drugs such as heroin and prescription pain relievers.^20,27 It is these aspects of kratom pharmacology that have received the most scientific attention. Although to our knowledge, no well-controlled clinical studies on the effects of kratom on humans have been published, there is evidence^30-38 that kratom, kratom extracts, and molecules isolated from kratom can alleviate various forms of pain in animal models. Studies have used a variety of methods including hot plate,^35,37,39 tail flick,^32,39 writhing,^37,38 and pressure/inflammation^35,38 tests in mice^32,35,38,39 and rats,^35,37 as well as more elaborate tests in dogs and cats.³⁵ In addition, a variety of chemical compounds have been isolated from kratom and shown to exhibit opioid-like activity on smooth muscle systems^31,33,34 and in ligand-binding studies.^39,40 Most notably, many of the central nervous system and peripheral effects of these kratom-derived substances are sensitive to inhibition by opioid antagonists.^31-34,39-41"