Fasting improves oral bioavailability of mitragynine in healthy female Beagles

To evaluate the pharmacokinetic profile and safety of an encapsulated kratom extract when administered orally to fed and fasted healthy female Beagles.

The study was conducted over a 24-hour period in June 2023. Dogs were randomly assigned to 2 groups (4 dogs each). All dogs received 8 mg (targeted mitragynine dose of 0.55 to 0.68 mg/kg) of a formulated kratom extract per capsule (45% mitragynine, weight-for-weight kratom extract). One group was administered the capsule with food and the other after fasting. Blood sampling was performed at fixed time points over 24 hours. Plasma concentrations of mitragynine and its metabolites were measured using UPLC-MS-MS. Safety assessment included clinical monitoring of vital signs, and a CBC and biochemical analysis before and 24 hours after dosing.

Peak plasma concentration of mitragynine in the fasted group was 55.2 ± 6.1 ng/mL and occurred at 1.3 ± 0.3 hours postdose. In contrast, the peak plasma concentration of mitragynine in the fed group was 25.6 ± 6.7 ng/mL and occurred at 7.5 ± 2.1 hours postdose. Relative bioavailability with food was 30% lower than in the fasted group. Administration of a single oral dose of an encapsulated kratom extract was well tolerated, with no adverse effects.

Rapid absorption and greater systemic exposure of mitragynine were achieved when encapsulated kratom extract was administered on an empty stomach.

Greater pharmacologic potential should be expected when encapsulated kratom extract is administered to fasted animals.