The US National Institute on Drug Abuse (NIDA) has established a standard dose for THC, a decision that will help medical cannabis researchers compare the results of new clinical studies.
Last March, NIDA published a notice asking scientists and researchers for advice on creating an optimal standard dose for THC. At the time, the agency wrote that “research grows ever more critical to determine both the adverse health effects and therapeutic potential of cannabis and its constituents. Recognizing that a perfect measure may not be attainable at the current time, NIDA still believes that a standard dose would improve measures of outcomes in relation to exposure; and thus, could inform policy and public health strategies around cannabis use.”
NIDA gave interested parties until May 1st, 2020 to submit feedback on a recommended standard dose. This May, one full year after closing the public commentary period, the agency has finally announced its decision. Effective immediately, the federal standard dose for THC is 5 milligrams. In a new notice, NIDA is advising researchers that they must now measure and report the results of all cannabis research using this standard unit of measurement.
Researchers have been conducting clinical studies on THC and cannabis for more than fifty years, but without an official standard dose, each individual research team has had to devise its own measurements for weed. In many studies, researchers only kept track of the total number of joints or weight of flower that subjects smoked. Each individual strain of weed has unique levels of THC and other cannabinoids, though, which makes it difficult to draw serious conclusions from these vague measurements.
In a new federal notice, NIDA explained that inconsistencies in measuring and reporting THC levels have “been a major limitation in studies of cannabis use, making it difficult to compare findings among studies.” To resolve this issue, the agency decided that a “standardized measure of THC in cannabis products is necessary to advance research by providing greater comparability across studies of both its adverse effects and potential medical uses.”
Even so, NIDA warns that “the same quantity of THC may have different effects based on route of administration, other product constituents, an individual’s genetic make-up and metabolic factors, prior exposure to cannabis, and other factors.” And since the agency has not established a standard dose for CBD or other cannabinoids, it will remain difficult for researchers to compare studies that use different strains of flower or full-spectrum extracts.
The adoption of this new standard dose is not intended to limit the amount of THC that researchers can use in clinical cannabis research. “Indeed, investigators are free to use more or less than 5mg of THC as appropriate for their study,” NIDA clarified in the notice. “However, for applicable studies, investigators will be required to report the quantity of THC using the standard unit. Investigators may also report the quantity of THC in other units (e.g., milligrams) as appropriate.”
The federal government still considers cannabis a Schedule I drug with no medical use, but NIDA Director Nora Volkow has been working to create regulations like this new standard dose in order to help researchers better understand this complicated plant.
“Although cannabis remains an illicit substance in the United States, the expanded legalization by states requires us to develop the knowledge base that can help states develop policies to minimize risk from cannabis exposures, such as limits on the THC content of cannabis products,” Volkow wrote in a commentary published in the Addiction journal last year.