(Adds details from FDA statement)
May 22 (Reuters) - The U.S. Food and Drug Administration said on Tuesday it issued warning letters to three companies that illegally marketed and distributed products containing the substance, kratom, which they claimed treat opioid addiction and withdrawal.
The regulator has been clamping down on the substance, which it says has similar effects to narcotics such as opioids and has resulted in dozens of deaths.
The leaves of the kratom tree, native to Southeast Asia, can be used as a stimulant or sedative.
Front Range Kratom of Aurora, Colorado; Kratom Spot of Irvine, California; and Revibe Inc of Kansas City, Missouri received letters for illegally selling unapproved kratom-containing drug products with unproven claims, the FDA said http://pdf.reuters.com/htmlnews/htmlnews.asp?i=43059c3bf0e37541&u=urn:newsml:reu t e r s . c o m : 2 0 1 8 0 5 2 2 : n P n 6 4 X F y j a .
"Despite our warnings that no kratom product is safe, we continue to find companies selling kratom and doing so with deceptive medical claims for which there's no reliable scientific proof to support their use," FDA Commissioner Scott Gottlieb said in a statement.
While kratom is not controlled under the Federal Controlled Substances Act, the U.S. Drug Enforcement Administration has listed it as a "drug and chemical of concern".
The FDA has not approved it for any medical use and marketing it with claims that it can treat medical complications is a federal offence.
The warning letters included more than 65 kratom products with names like "Super Green Indo Kratom Capsules" and "50x Black Diamond Extract", some of which claimed to treat pain, lower blood pressure, treat cancer and reduce neuron damage caused by strokes, the FDA said.
Front Range Kratom and Kratom Spot did not immediately respond to requests for comment. Reuters was unable to reach Revibe Inc. (Reporting by Tamara Mathias in Bengaluru; Editing by Bernard Orr and Maju Samuel)