Valsartan is a potent, orally active non-
peptide tetrazole derivative and selectively inhibits
angiotensin II receptor type 1 which causes reduction in blood pressure and is used in treatment of
hypertension. The risk of
heart disease mortality decreased significantly as
flavonoid intake increased. Interestingly, the
flavonoid-containing foods contain a high amount of
Quercetin. The objective of this study was to evaluate the influence of
quercetin on the pharmacokinetics of
valsartan. In vivo studies were performed on rats. Rats were treated with
quercetin (10 mg/kg) and
valsartan (10 mg/kg), blood samples were collected at 1, 1.5, 2, 2.5, 3, 3.5, 4, 6 and 8 h. Plasma concentration of
valsartan was estimated by Reverse Phase (RP-HPLC).
Quercetin significantly increases the plasma concentration of
valsartan and peak concentration (70.45 µg/mL) was achieved at 3.5 h. In vitro studies were performed on rat intestinal everted sacs. The transport of
valsartan from serosal side to mucosal side decreased from 53.12 ± 1.27 to 40.15 ± 0.45 µg/mL in the presence of
quercetin and from 53.12 ± 1.27 to 28.68 ± 0.31 µg/mL in the presence of
verapamil (standard
P-glycoprotein (P-gp) inhibitor) at 120 min.
Verapamil is a potent P-gp and
CYP3A4 inhibitor.
Quercetin is a P-gp inhibitor and may be an inhibitor of
CYP3A4. The simultaneous administration of
quercetin significantly increases the intestinal absorption and decreases the efflux of
valsartan. The observed effect may be beneficial to develop oral
valsartan dosage forms using safe P-gp inhibitor (
quercetin) to improve its oral bioavailability.