On February 2018, the FDA published the results of a basic computer model and misleadingly declared kratom an opioid, declaring it as a problem rather than a possible painkiller. It followed up within two weeks by issuing a “voluntary destruction” and recall to a Missouri-based manufacturer of more than 142,000 kratom-containing capsules, along with just over 11 kilograms of kratom powder. The agency also asked the manufacturer to stop selling any kratom-containing products, quoting FDA Commissioner Scott Gottlieb as saying:
“The extensive scientific data we’ve evaluated about kratom provides conclusive evidence that compounds contained in kratom are opioids and are expected to have similar addictive effects as well as risks of abuse, overdose and, in some cases, death. At the same time, there’s no evidence to indicate that kratom is safe or effective for any medical use.”
But Andrew Kruegel, a Columbia University pharmacologist who has extensively studied kratom, is less than impressed.
“I don’t really see what this adds to this field or adds to the body of knowledge around kratom; it’s very strange to me.”
Basically, the FDA attempted to match a computer model of a compound with its receptors in the body—known as molecular modeling or molecular docking. It’s used in the early stages of drug development: by choosing a receptor to target, researchers could cycle through tens of thousands of compound models, looking for one that might activate the receptor.
“But that’s a very early step in drug development,” Kruegel says. “You would not be very confident in the results of that assay. It’s all done virtually in a computer.”
There’s still the laborious process of producing the compound and testing it in actual living things—with no guarantee it’ll have the expected effect.
In Kruegel’s own research, published in 2016, which examines how compounds in kratom, particularly mitragynine, only partially activate certain opioid receptors, yet have distinct pharmacological properties. But not every opioid has the same effect. Naloxone, for example, binds to opioid receptors, but is actually used to reverse opioid overdoses. (Addiction treatment medications buprenorphine, naltrexone, and methadone also attach to opioid receptors.) That’s why researchers carefully examine how opioids actually work in the body.
“The problem with saying it’s ‘an opioid’ without qualification is that it just paints everything with this broad brush, and obviously carries a negative connotation given what’s going on in the country right now,” Kruegel says.
Most scientists share the same view with Kruegel. They know that any data based on preliminary computer models are merely hypothesis and does not substantiate a scientific conclusion. Better understanding on how certain opioids produce certain effects is key to developing safer painkillers.