Conversion of water-soluble CBD to Δ9-THC in synthetic gastric fluid – an unlikely cause of positive drug tests

Cannabidiol (CBD) has been shown to convert to Δ9-tetrahydrocannabinol (Δ9-THC) in acidic environments, raising a concern of conversion when exposed to gastric fluid after consumption. Using synthetic gastric fluid (SGF), it has been demonstrated that the conversion requires surfactants, such as sodium dodecyl sulfate (SDS), due to limited solubility of CBD. Recently, water-compatible nano-emulsions of CBD have been prepared as a means of fortifying beverages and water-based foods with CBD. Since these emulsions contain surfactants as part of their formulation, it is possible that these preparations might enhance the production of Δ9-THC even in the absence of added surfactants. Three THC-free CBD products; an oil, an anhydrous powder, and a water-soluble formulation were incubated for 3 hours in SGF without SDS. The water-soluble CBD product produced a dispersion while the powder and the oil did not mix with the SGF. No THC was detected with the CBD oil (<0.0006% conversion), and up to 0.063% and 0.0045% conversion to Δ9-THC was observed with the water-soluble CBD and the CBD powder, respectively. No formation of Δ8-THC was observed. In comparison, when the nano-formulated CBD was incubated in SGF with 1% SDS, 33-36% conversion to Δ9-THC was observed. Even though the rate of conversion with the water-soluble CBD was at least 100-fold higher compared to the CBD oil, it was still smaller than Δ9-THC levels reported in CBD products labelled “THC-free” or “<0.3% THC” based on the Agricultural Improvement Act of 2018 (the Farm Bill). Assuming a daily CBD dose of around 30 mg/day, it is unlikely that conversion of CBD to Δ9-THC could produce a positive urinary drug test for Δ9-THC-COOH (15 ng/mL cutoff).