Cannabis constituents interact at the drug efflux pump BCRP to markedly increase plasma cannabidiolic acid concentrations

Abstract

Cannabis is a complex mixture of hundreds of bioactive molecules. This provides the potential for pharmacological interactions between cannabis constituents, a phenomenon referred to as "the entourage effect" by the medicinal cannabis community. We hypothesize that pharmacokinetic interactions between cannabis constituents could substantially alter systemic cannabinoid concentrations. To address this hypothesis we compared pharmacokinetic parameters of cannabinoids administered orally in a cannabis extract to those administered as individual cannabinoids at equivalent doses in mice. Astonishingly, plasma cannabidiolic acid (CBDA) concentrations were 14-times higher following administration in the cannabis extract than when administered as a single molecule. In vitro transwell assays identified CBDA as a substrate of the drug efflux transporter breast cancer resistance protein (BCRP), and that cannabigerol and Δ⁹-tetrahydrocannabinol inhibited the BCRP-mediated transport of CBDA. Such a cannabinoid-cannabinoid interaction at BCRP transporters located in the intestine would inhibit efflux of CBDA, thus resulting in increased plasma concentrations. Our results suggest that cannabis extracts provide a natural vehicle to substantially enhance plasma CBDA concentrations. Moreover, CBDA might have a more significant contribution to the pharmacological effects of orally administered cannabis extracts than previously thought.

Figure 1

Pharmacokinetic analysis of orally administered cannabinoids in mouse plasma. Cannabinoids were administered orally as either a full-spectrum cannabis extract or individually at equivalent doses to those in the full-spectrum extract. (a) Dose and profile of cannabinoids within the full-spectrum extract (left panel) vs. the cannabinoids administered individually (right panel). Concentration–time curves for (b) CBDA, (c) CBD (d) CBDVA (e) CBGA (f) Δ⁹-THC and (f) Δ⁹-THCA. Concentrations are depicted as both mass concentrations (left y-axis) and molar concentrations (right y-axis) for each cannabinoid administered as a full-spectrum extract (solid symbols) or as an individual compound (open symbols). Data are expressed as means ± SEM, with n = 4–5 per time point.

Figure 2

CBD, CBDA, CBDVA, CBG and Δ⁹-THC are substrates of BCRP. Concentration–time curves for (a) CBDA, (b) CBD, (c) CBDVA, (d) CBG and (e) Δ⁹-THC in wildtype (left panel) and BCRP-expressing (middle panel) MDCK cells in the basolateral to apical (B > A) and apical to basolateral (A > B) directions. Right panels represent concentration–time curves for cannabinoids in cells expressing BCRP in the presence of the inhibitor elacridar (dashed lines). Data are expressed as means ± SEM, with n = 4 per time point. Curves represent fits to a linear regression and transport efflux ratios (r) are listed (*p < 0.05, **p < 0.005, ***p < 0.0005 compared to wildtype; Extra sum-of-squares F test).

Figure 3

CBG and Δ⁹-THC inhibit BCRP-mediated transport of CBDA. Concentration–time curves for CBDA in the presence of (a) vehicle, (b) CBG, (c) Δ⁹-THC and (d) CBD, (e) CBDVA and (f) a mixture of all four cannabinoids in the basolateral to apical (B > A) and apical to basolateral (A > B) directions in cells expressing BCRP. Cannabinoids were tested at 10 µM. CBG and Δ⁹-THC significantly inhibit (red shading) transport of CBDA. Data are expressed as means ± SEM, with n = 4 per time point. Curves represent fits to a linear regression and transport efflux ratios (r) are listed (*p < 0.05, ***p < 0.0005, ****p < 0.0001 compared to vehicle; Extra sum-of-squares F test). (g) Schematic of CBDA efflux by BCRP located in the intestinal lumen when administered alone (left panel) or as a full-spectrum cannabis extract where its efflux is inhibited by CBG and Δ⁹-THC (right panel). Schematic created using BioRender.com.

Figure 4

CBD inhibits BCRP-mediated transport. Concentration–time curves for prazosin in the presence of (a) vehicle, (b) elacridar, (c) CBD (d) CBDA, (e) CBDVA, (f) CBG or (g) Δ⁹-THC in the basolateral to apical (B > A) and apical to basolateral (A > B) directions in cells expressing BCRP. Elacridar and CBD significantly inhibit (red shading) transport of prazosin. Data are expressed as means ± SEM, with n = 3–4 per time point. Curves represent fits to a linear regression and transport efflux ratios (r) are listed (*p < 0.05, **p < 0.005, ***p < 0.0005 compared to vehicle; Extra sum-of-squares F test).

Figure 5

CBDA inhibits P-glycoprotein-mediated transport. Concentration–time curves for prazosin in the presence of (a) vehicle, (b) loratadine, (c) CBDA (d) CBD, (e) CBDVA, (f) CBG or (g) Δ⁹-THC in the basolateral to apical (B > A) and apical to basolateral (A > B) directions in cells expressing BCRP. Elacridar and CBD significantly inhibit (red shading) transport of prazosin. Data are expressed as means ± SEM, with n = 3–4 per time point. Curves represent fits to a linear regression and transport efflux ratios (r) are listed (*p < 0.05, compared to vehicle; Extra sum-of-squares F test).