TABLE 3.
Clinical pharmacokinetics of key kratom alkaloids after oral administration of kratom tea to healthy adult participants
| Study | Trakulsrichai et al. (2015) | Tanna et al. (2022) | ||||||
|---|---|---|---|---|---|---|---|---|
| Participants (n) | 10 | 5 | ||||||
| Mean ± S.D. | Median (Range) | |||||||
| Alkaloid | Mitragynine | Mitragynine | Speciogynine | Paynantheine | Speciociliatine | Mitraciliatine | Isopaynantheine | 7-Hydroxy-Mitragynine |
| Dose (mg) | Variablea | 39 | 6.4 | 12 | 10 | 1.3 | 1.0 | — |
| Cmax (nM) | — | 81.9 (50.1–177) | 51.4 (34.2–121) | 61.1 (56.4–157) | 308 (154–380) | 73.5 (34.9–98.6) | 48.8 (26.2–68.2) | 16.1 (11.9–22.2) |
| tmax (h) | 0.83 ± 0.35 | 1 (0.75–1.5) | 2 (1–3.5) | 1 (0.75–2.5) | 2.5 (1–3.5) | 4.5 (3.5–6.5) | 4.5 (2.5–6.5) | 1 (0.75–2.5) |
| t1/2 (h) | 23 ± 16 | 45.3 (31.9–50.2) | 23.5 (16.1–28.3) | 27.0 (17.7–30.8) | 12.3 (10.4–21.1) | 17.8 (11.2–24.7) | 14.4 (11.8–20.9) | 5.67 (5.03–6.52) |
| AUCinf (nMh) | — | 420 (324–1360) | 477 (379–1120) | 438 (389–956) | 5120 (3200–7560) | 1160 (1040–3520) | 794 (667–2130) | 106 (60.8–126) |
| Vz/F (L) | 2900 ± 1850b | 12,700 (5190–19,700) | 962 (584–1235) | 1940 (1370–2620) | 130 (60.1–159) | 46.0 (26.2–74.0) | 55.5 (36.6–76.0) | — |
| CL/F (l/h) | 7550 ± 3900b | 233 (71.7–302) | 33.5 (14.3–42.1) | 67.4 (30.9–76.0) | 5.01 (3.40–8.04) | 2.78 (0.92–3.11) | 3.25 (1.21–3.87) | — |
—, information not available.
AUCinf, area under the plasma concentration-time profiles from time zero to infinity; CL/F, oral clearance; t1/2, terminal elimination half-life; Tmax, time to reach Cmax; Vz/F, apparent volume of distribution during the terminal phase.
aA range of doses (6.25–23 mg) of mitragynine contained in a kratom tea were administered, precluding direct comparison of Cmax and AUCinf between studies.
bObtained by multiplying the Vd/F in l/kg with the mean weight (77 kg) of the participants; blood was collected from 0 to 24 hours, yet an average terminal half-life of ∼24 hours was reported, raising concerns about the accuracy of the reported pharmacokinetic outcomes, including t1/2, CL/F, and Vz/F.