Pharmacokinetics and biochemical efficacy of idrapril calcium, a novel ACE inhibitor, after multiple oral administration in humans

Quercetin: A Treatment for Hypertension?-A Review of Efficacy and Mechanisms

Quercetin is a polyphenolic flavonoid. Common sources in the diet are apples, onions, berries, and red wine. Epidemiological studies have found an inverse relationship between dietary quercetin intake and cardiovascular disease. This has led to in vitro, in vivo, and clinical research to determine the mechanism by which quercetin exerts cardio-protective effects. Recent studies have found a reduction in blood pressure when hypertensive (>140 mm Hg systolic and >90 mm Hg diastolic) animals and humans are supplemented with quercetin. Proposed mechanisms for the antihypertensive effect of quercetin include decreased oxidative stress, inhibition of angiotensin converting enzyme activity, improved endothelial function, direct action on the vascular smooth muscle, and/or modulation in cell signaling and gene expression. Although in vitro and in vivo evidence exists to support and refute each possibility, it is likely that quercetin influences multiple targets via a combination of known and as yet undiscovered mechanisms. The purpose of this review is to examine the mechanisms whereby quercetin might reduce blood pressure in hypertensive individuals.

Reductive metabolism and its role in the disposition of the hydroxamic angiotensin-converting enzyme inhibitor idrapril calcium in rat

1. The metabolism of 14C-idrapril calcium, the prototype of a new class of angiotensin-converting enzyme inhibitors, was studied in rat after a single intravenous administration. Plasma, urine, faeces, and bile were assayed for total and hplc-fractionated radioactivity. 2. Only one major metabolite (M1, 2-sarcosinamide-cis-1,2-cyclohexanedicarboxylamide) was observed, along with idrapril, in plasma. Three metabolites (M1, M2, cis-1,2-cyclohexanedicarboxylic acid, and M3, a glucuronate derivative of M1) were present in 0-8-h urine, unchanged idrapril being the most abundant product. In bile, two metabolites (M1, M3), but not the parent compound, were found. 3. In conclusion intravenous idrapril undergoes hepatic reduction to M1 and hydrolysis to M2. M1 can be glucuronated to M3 and both are partially excreted in the bile and further processed in the gut to reabsorbable radioactive species.