Angiotensin II receptor antagonists - antihypertensive agents

Resveratrol attenuates angiotensin II-induced interleukin-6 expression and perivascular fibrosis

Recent studies have shown that resveratrol (3,5,4'-trihydroxystilbene), a polyphenolic compound found in grapes and red wine, has various beneficial effects on cardiovascular diseases and prolongs the life span of mice fed a high-fat diet. We hypothesized that resveratrol may attenuate vascular inflammatory response induced by angiotensin (Ang) II. We examined the effect of resveratrol on Ang II-induced interleukin (IL)-6 expression in vascular smooth muscle cells (VSMCs). Resveratrol significantly attenuated Ang II-induced IL-6 mRNA expression and IL-6 protein in the supernatant of VSMC in a dose-dependent manner. Resveratrol suppressed the IL-6 gene promoter activity. Resveratrol inhibited the Ang II-induced cAMP-response element-binding protein and nuclear factor-kappa B activity, which are critical for Ang II-induced IL-6 gene activation. An increase in the serum concentration of IL-6 induced by Ang II infusion was attenuated by an oral administration of resveratrol. Resveratrol also inhibited Ang II-induced hypertension and perivascular fibrosis of the heart. Although hydralazine reduced blood pressure level equal to resveratrol, it did not reduce the Ang II-induced IL-6 production and perivascular fibrosis. These data suggest that the inhibition of Ang II-induced vascular inflammation and high blood pressure by resveratrol may contribute, at least in part, to the anti-atherogenic effects of resveratrol.

Stereoselective synthesis of renin inhibitor BILA 2157 BS

We have developed a convergent and stereoselective synthesis of orally active renin inhibitor BILA 2157 BS. Three building blocks were used to generate the basic skeleton of the inhibitor. The key feature consisted of the late elaboration of the 2-amino-4-thiazolyl heterocycle from a vinylbromide precursor. The synthetic sequence, which required a total of 22 chemical steps, provided 0.6 kg of BILA 2157 BS in 7.3% overall yield.Key words: renin, inhibitor, peptidomimetic, stereoselective synthesis.

Evaluation of the angiotensin challenge methodology for assessing the pharmacodynamic profile of antihypertensive drugs acting on the renin-angiotensin system

AIMS

The performance of the experimental paradigm of angiotensin challenges with continuous non-invasive blood pressure measurement was evaluated. Angiotensin dose-response relationships were characterized, along with the influence of clinical covariates. The stability of angiotensin-induced peaks and the variability of the angiotensin doses were assessed. Finally, the predictive value of studies based on angiotensin challenges to determine drug doses effective in therapeutics was evaluated.

METHODS

The data were gathered from 13 clinical studies on nine angiotensin II receptor antagonists, one ACE inhibitor and one dual ACE-NEP inhibitor, using Finapres for measuring the response to exogenous angiotensin challenges. Modelling of angiotensin dose-response curves and determination of the inter and intrasubject variability were performed by nonlinear regression (NONMEM). The different sources of variations in angiotensin I and II doses and angiotensin-induced peaks were evaluated by analyses of variance. The dose of ACE inhibitors and angiotensin II receptor antagonists inhibiting blood pressure increase by at least 75%, as measured by this method, was chosen for comparison with the labelled starting dose.

RESULTS

Angiotensin challenges exhibited a clear dose-response relationship which can be characterized both by an Emax or a log linear model. The log linear model gave an average systolic/diastolic response of 24+/-6/20+/-5 mmHg for a unit dose of 1 microgram of angiotensin II equivalents, and an increase of 6/6 mmHg for each doubling of the dose. The angiotensin ED50 calculated values were 0.67 microgram for systolic and 0.84 microgram for diastolic blood pressure. The angiotensin doses for eliciting a given response and the angiotensin induced peaks were fairly constant between period and subject, but vary significantly between studies. Based on an inhibition of blood pressure by 75%, the agreement was good between the doses of ACE inhibitors and angiotensin receptor antagonists predicted from studies using the methodology of angiotensin challenges and the doses shown to be clinically efficacious, in spite of high intersubject and intrasubject variabilities.

CONCLUSIONS

This experimental method represents a valid surrogate for the therapeutic target and a useful tool for the pharmacokinetic and pharmacodynamic profiling of drugs acting on the renin-angiotensin system.

Discovery of non-peptidic P2-P3 butanediamide renin inhibitors with high oral efficacy

A new series of non-peptidic renin inhibitors having a 2-substituted butanediamide moiety at the P2 and P3 positions has been identified. The optimized inhibitors have IC50 values of 0.8 to 1.4 nM and 2.5 to 7.6 nM in plasma renin assays at pH 6.0 and 7.4, respectively. When evaluated in the normotensive cynomolgus monkey model, two of the most potent inhibitors were orally active at a dose as low as 3 mg/kg. These potent renin inhibitors are characterized by oral bioavailabilities of 40 and 89% in the cynomolgus monkey. Inhibitor 3z (BILA 2157 BS) was selected as candidate for pre-development.

Angiotensin II receptor antagonists in hypertension

Blockade of the renin-angiotensin system is now recognized as an effective approach to the treatment of hypertension and congestive heart failure. Today, it is possible to antagonize the effects of angiotensin II more specifically by blocking its receptors by using nonpeptide receptor antagonists. These compounds that first have been used to recognize the various subtypes of angiotensin II receptors are now available clinically. Four of them have recently been launched on the market and several others are preregistered for the treatment of hypertension. These new molecules are as effective as ACE inhibitors, calcium antagonists and beta-blockers in lowering blood pressure in hypertensive patients. When compared to ACE inhibitors, they appear to have comparable favorable effects on systemic and renal hemodynamic properties. One of the major characteristics of angiotensin II receptor antagonists as a class is the excellent tolerability with an incidence of side effects that is generally similar to that of placebo. Large clinical trials are now underway to demonstrate the long-term benefits of these agents in hypertension, heart failure and type II diabetic nephropathy.

Effect of indomethacin on the renal response to angiotensin II receptor blockade in healthy subjects

BACKGROUND

Non-steroidal anti-inflammatory drugs are known to promote sodium retention and to blunt the blood pressure lowering effects of several classes of antihypertensive agents including beta-blockers, diuretics and angiotensin converting enzyme (ACE) inhibitors. The purpose of the present study was to investigate the acute and sustained effects of indomethacin on the renal response to the angiotensin II receptor antagonist valsartan and to the ACE inhibitor enalapril.

METHODS

Twenty normotensive subjects maintained on fixed sodium intake (100 mmol sodium/day) were randomized to receive for one week: valsartan 80 mg o.d., enalapril 20 mg o.d., valsartan 80 mg o.d. + indomethacin 50 mg bid and enalapril 20 mg o.d. + indomethacin 50 mg bid. This single-blind study was designed as a parallel (valsartan vs. enalapril) and cross-over trial (valsartan or enalapril vs. valsartan + indomethacin or enalapril + indomethacin). Renal hemodynamics and urinary electrolyte excretion were measured for six hours after the first and seventh administration of each treatment regimen.

RESULTS

The results show that valsartan and enalapril have comparable renal effects characterized by no change in glomerular filtration rate and significant increases in renal plasma flow and sodium excretion. The valsartan- and enalapril-induced renal vasodilation is not significantly blunted by indomethacin. However, indomethacin similarly abolishes the natriuresis induced by the angiotensin II antagonist and the ACE inhibitor.

CONCLUSIONS

This observation suggests that although angiotensin receptor antagonists do not affect prostaglandin metabolism, the administration of a non-steroidal anti-inflammatory drug blunts the natriuretic response to angiotensin receptor blockade.

Angiotensin II receptor antagonists and treatment of hypertension and renal disease

Angiotensin II, the principal effector of the renin-angiotensin cascade, stimulates a variety of physiological responses that support blood pressure and renal function. Abnormal generation of angiotensin II also contributes to the pathogenesis of hypertension, arterial diseases, cardiac hypertrophy, heart failure and proteinuric progressive renal diseases. It is well recognized that angiotensin-converting enzyme inhibitors effectively limit the progression of diabetic and non-diabetic proteinuric renal diseases towards end-stage renal disease, a capacity not necessarily shared by other blood pressure lowering agents. Whether angiotensin II type 1 receptor antagonists have the same renoprotective effect as angiotensin-converting enzyme inhibitors in progressive renal diseases remains ill defined. Angiotensin II type 1 receptor antagonists as antiproteinuric agents have been used originally in animal models of renal disease progression. Results have shown that angiotensin II type 1 receptor blockers are as effective as angiotensin-converting enzyme inhibitors in normalizing proteinuria in models of renal disease. Studies in humans are very few, but those that have been undertaken report consistent antiproteinuric effects of angiotensin II type 1 receptor antagonists that are similar to those with angiotensin-converting enzyme inhibitors. Long-term studies, however, are required to examine whether the antiproteinuric effects of angiotensin II type 1 receptor antagonists can be translated into renoprotection.