Abstract: AIM: To investigate the effect of regular consumption of RRR-α-tocopherol on the activity of P-gp in vivo.METHODS: In a two-stage doubly periodic cross-over study, 12 healthy volunteers, who were randomly divided into two groups, ingested RRR-α-tocopherol 600 mg each day or placebo (control) for 14 d. On day 15, a single 100 mg dose of talinolol was administered by all the volunteers and 5 mL peripheral vein blood of each one was taken at 0, 0.25, 0.5, 0.75, 1, 1.5, 2, 2.5, 3, 4, 6, 8, 12, 24 h. Plasma concentrations of talinolol were determined by HPLC after centrifugation and blood plasma separation. The difference of pharmacokinetic parameters of every groups were compared and analyzed.RESULTS: Co-administration of RRR-α-tocopherol obviously decreased the area under the curve AUC_(0-24h) of talinolol [(2104±670) ng·h·mL^-1 vs (2914±1061) ng·h·mL^-1], P<0.05, and significantly decreased C_max of talinolol [(249±69) ng/mL vs (406±214) ng/mL], P<0.05.CONCLUSION: Regular consumption of RRR-α-tocopherol 600 mg each day for 14 d, significantly induces the activity of P-gp.

Key words: RRR-α-tocopherol, Talinolol, PXR, P-gp