Effects of single green tea ingestion on pharmacokinetics of nadolol in healthy volunteers

AIMS: The aim of this study was to investigate the effects of a single green tea (GT), administered concomitantly or 1 hour before nadolol intake on nadolol pharmacokinetics. METHODS: In a randomized 3‐phase crossover study, 11 healthy volunteers received an oral administration of nadolol with, or 1 hour after preingestion of brewed GT, or with water in a volume of 150 mL. RESULTS: Geometric mean ratio with 90% confidence interval for nadolol AUC(0–48) was 0.371 (0.303–0.439) with concomitant GT. In addition, ingestion of GT 1 hour before nadolol administration resulted in a significant reduction of nadolol AUC(0–48) with geometric mean ratio of 0.536 (0.406–0.665). There were no differences in time to maximal plasma concentration and renal clearance of nadolol among groups. CONCLUSION: These results suggest that single concomitant ingestion of GT substantially decreases plasma concentrations of nadolol. Moreover, the reduction in nadolol bioavailability could persist for at least 1 hour after drinking a cup of GT.