FDA Analysis Finds Evidence of Kratom’s Opioid Properties

Death toll linked with Asian plant rises to 44

A scientific analysis found stronger evidence that compounds in kratom have opioid properties, according to FDA Commissioner Scott Gottlieb, MD, who added that the agency has now received 44 reports of deaths linked to the Asian plant.

In November 2017, the FDA warned the public not to use kratom (Mitragyna speciose), which grows naturally in Thailand, Malaysia, Indonesia, and Papua New Guinea. The agency said the plant appeared to expose users to the risks of addiction, abuse, and dependence.

“We have been especially concerned about the use of kratom to treat opioid withdrawal symptoms, as there is no reliable evidence to support the use of kratom as a treatment for opioid use disorder and significant safety issues exist,” the FDA commissioner said.

The FDA conducted a scientific analysis using a computational model developed by agency scientists, he said. The Public Health Assessment via Structural Evaluation (PHASE) methodology uses 3D computer technology to help simulate how the chemical constituents of a substance (such as the compounds and alkaloids found in kratom) are structured at a molecular level, how they may behave inside the body, and how they can potentially affect the brain.

The FDA analyzed the chemical structures of the 25 most prevalent compounds in kratom. “From this analysis, the agency concluded that all of the compounds share the most structural similarities with controlled opioid analgesics, such as morphine derivatives,” Dr. Gottlieb said. The model predicted that 22 of the 25 compounds in kratom (including mitragynine) bind to mu-opioid receptors. This model and previously available experimental data confirmed that two of the top five most prevalent compounds (including mitragynine) activate opioid receptors.

“The new data provides even stronger evidence of kratom compounds’ opioid properties,” Dr. Gottlieb said. “The data from the PHASE model shows us that kratom compounds are predicted to affect the body just like opioids. Based on the scientific information in the literature and further supported by our computational modeling and the reports of its adverse effects in humans, we feel confident in calling compounds found in kratom, opioids.”

The FDA previously placed kratom products on import alert to prevent them from entering the country illegally and has seized several batches.

The FDA has updated the death toll related to kratom from 36 in November 2017 to 44. In at least one case, the person who died had no known historical or toxicologic evidence of opioid use except for kratom. In other cases, kratom was used in combination with other drugs that affect the brain, including illicit drugs, prescription opioids, benzodiazepines, and over-the-counter medications.

“Kratom should not be used to treat medical conditions, nor should it be used as an alternative to prescription opioids,” Dr. Gottlieb said. “There is no evidence to indicate that kratom is safe or effective for any medical use. And claiming that kratom is benign because it’s ‘just a plant’ is shortsighted and dangerous.”

“For individuals seeking treatment for opioid addiction who are being told that kratom can be an effective treatment, I urge you to seek help from a health care provider,” Dr. Gottlieb added. “There are safe and effective, FDA-approved medical therapies available for the treatment of opioid addiction. Combined with psychosocial support, these treatments are effective.”

Sources: FDA; February 6, 2018; FDA; November 2017.