Abstract: AIM: To observe the effect of orange juice on the pharmacokinetics of p-glycoprotein (PGP) substrate drug talinolol. METHODS: 12 healthy adult men were enrolled in this clinical trial with a 2-phase randomized crossover design.In each phase the volunteers received placebo water or 200 mL orange juice 3 times daily for 3 consecutive days, on the fourth day, all subjects took 100 mg talinolol tablet after treated either with orange juice or placebo water one more time, blood samples were collected up to 36 hours with a 7-day washout period.Plasma talinolol were measured by HPLC.Pharmacokinetic parameters between orange juice and placebo water treatment groups were compared. RESULTS: Orange juice treatment reduce the plasma talinolol concentrations, decreases C_max and AUC by 47.6% [(166±44) ng/mL versus (317±119) ng/mL] and 27%[(1783±494) ng·mL^-1·h versus (2456±1048) ng·mL^-1·h].The time to reach maximal talinolol concentration was markedly prolonged, 2.5 h (1.5-4 h) versus 4 h (2.5-6 h), there was no significant difference for half life of talinolol between the two groups(P> 0.05). CONCLUSION: The orange juice substantially reduces the absorption and the bioavailability of talinolol, to such a great extent of the orange juice-talinolol interaction, it is likely to have clinical importance, not only for talinolol, but also for those drugs which share the same transport protein.

Key words: talinolol, orange juice, pharmacokinetics