Enhancing the Bioavailability of Quercetin by Concomitant Administration with Enzyme Inhibitor

Background: Quercetin is a food supplement with multiple biological activities including antihypertensive, vasodilator effects, antiobesity, antihypercholesterolemic, antiatherosclerotic and other activities, it is available in wide range of dietary supplement and daily food intake, after oral ingestion, quercetin is metabolized by intestinal enzymes and absorbed by the duodenum, then be transported to the liver where is transformed into its glucuronidated, methylated and sulfo-substituted metabolites.Aim of Study: Boosting the bioavailability of Quercetin by enzyme inhibitor effect of ketoconazoleMethod: 10 apparently healthy adult, male (5) and female (5) were grouped A and B, with a 1-week wash-period, Group A received Quercetin 1000 mg, group B received Quercetin 1000 mg and Ketoconazole 400 mg, and 15 blood samples are collected on the following timing 0, 0.5 - 12.5 by 1 hour interval and other by hour 24 for HPLC Assay.Results: Concurrent ketoconazole administration with Quercetin significantly improves the mean plasma concentration under the curve from zero time to infinity (AUC0–∞) by 176% (403.41 ± 62.28 vs. 228.51 ± 28.67 μg.h/mL; P <0.0001) and prolonged time to complete elimination (44.66 ± 9.17 vs. 12.93 ± 1.4 hr.; P <0.0000) compared with Quercetin alone.Conclusion: Bioavailability of Quercetin will be increased by its administration together with ketoconazole, due to enzyme inhibiting effect of ketoconazole which delay elimination and increase the AUC of Quercetin.