Angiotensin II dose-effect curves and Schild regression plots for characterization of different angiotensin II AT1 receptor antagonists in clinical pharmacology

Prognostic Effect of Guideline-Directed Therapy Is More Noticeable Early in the Course of Heart Failure

BACKGROUND

There have been few studies to evaluate the prognostic implications of guideline-directed therapy according to the temporal course of heart failure. This study assessed the relationship between adherence to guideline-directed therapy at discharge and 60-day clinical outcomes in de novo acute heart failure (AHF) and acute decompensated chronic heart failure (ADCHF) separately.

METHODS

Among 5,625 AHF patients who were recruited from a multicenter cohort registry of Korean Acute Heart Failure, 2,769 patients with reduced ejection fraction were analyzed. Guideline-directed therapies were defined as the use of angiotensin-converting enzyme inhibitor (ACEI) or angiotensin receptor II blocker (ARB), β-blocker, and mineralocorticoid receptor antagonist.

RESULTS

In de novo AHF, ACEI or ARB reduced re-hospitalization (hazard ratio [HR], 0.57; 95% confidence interval [CI], 0.34-0.95), mortality (HR, 0.41; 95% CI, 0.24-0.69) and composite endpoint (HR, 0.52; 95% CI, 0.36-0.77) rates. Beta-blockers reduced re-hospitalization (HR, 0.62; 95% CI, 0.41-0.95) and composite endpoint (HR, 0.65; 95% CI, 0.47-0.90) rates. In ADCHF, adherence to ACEI or ARB was associated with only mortality and β-blockers with composite endpoint.

CONCLUSION

The prognostic implications of adherence to guideline-directed therapy at discharge were more pronounced in de novo heart failure. We recommend that guideline-directed therapy be started as early as possible in the course of heart failure with reduced ejection fraction.

Effects of AGTR1 A1166C gene polymorphism in patients with heart failure treated with candesartan

BACKGROUND

The benefits of angiotensin II receptor blockers (ARBs) in patients with heart failure who are treated with standard pharmacotherapy, including an angiotensin-converting enzyme (ACE) inhibitor, were demonstrated in 2 large randomized trials. It is currently impossible to determine which patient will benefit from the addition of an ARB.

OBJECTIVE

To explore the impact of selected candidate genes on the hemodynamic, neurohormonal, and antiinflammatory effects of candesartan in patients with heart failure who are already being treated with an ACE inhibitor.

METHODS

We investigated the impact of 10 candidate genetic polymorphisms on the effects of candesartan in patients with heart failure who are treated with an ACE inhibitor. We evaluated their impact on acute (2 wk) and long-term (24 wk) changes in blood pressure and N-terminal proB-type natriuretic peptide (NT-proBNP) and high sensitivity C-reactive protein (hsCRP) during treatment with candesartan.

RESULTS

Thirty-one patients were included. Homozygotes of the AGTR1 A1166 allele (n = 13) had a greater decrease in systolic (-9.1 +/- 4.7 vs 1.1 +/- 3.3 mm Hg; p = 0.04 by analysis of variance [ANOVA], adjusting for dose) and diastolic blood pressure (-5.1 +/- 1.5 vs 1.9 +/- 1.9 mm Hg; p = 0.005 by ANOVA, adjusting for dose) compared with C1166 allele carriers (n = 18) following 2 weeks of treatment. After 6 months of treatment, C1166 carriers experienced a greater decrease in NT-proBNP (-151.4 [-207; -19.8] ng/L vs 147.3 [-61.3; 882.9] ng/L; p = 0.03) and hsCRP (-0.8 [-2.2; -0.03] mg/L) vs 0.2 [-1.8; 5.3] mg/L; p = 0.09) compared with patients carrying the AA1166 genotype. No other significant association was found.

CONCLUSIONS

The results of this proof-of concept study provide the first evidence that the AGTR1 A1166C polymorphism could influence the response to candesartan in patients with heart failure who are receiving ACE inhibitors. Validation of these exploratory findings in larger populations is required before use of the AGTR1 A1166C genotype can be incorporated into clinical practice.

Blood pressure-lowering efficacy of olmesartan relative to other angiotensin II receptor antagonists: an overview of randomized controlled studies

The aim of the present work was to review published studies investigating the dose-related efficacy on blood pressure (BP) of olmesartan and of other commercially available angiotensin II type I receptor blockers (ARBs). Patient population comprises mild to moderate hypertensive adult patients. We selected studies with comparable design and dose ranges. Dose-effect relationship plots were fitted for diastolic (DBP) and systolic (SBP) BP to the simplified E(max) model. We also examined controlled studies of olmesartan vs. other individual ARBs. Our overview was based on 7280 patients, of which 5769 received an ARB and 1511 received placebo. Except for losartan, the data fitted correctly to the E(max) model, with correlation coefficients ranging from 0.77 to 0.99. BP-lowering efficacy defined as E(max) was superior with olmesartan, (DBP/SBP mmHg: -9.0/-12.4) when compared with candesartan (-6.7/-11.3), irbesartan (-6.5/-11.2) and valsartan (-6.3/-8.9). Head-to-head comparisons of olmesartan to each of the other ARBs used at per-label 'recommended doses', support the finding of a greater BP-lowering effect of olmesartan. This overview suggests that clinically relevant differences in maximal efficacy, as well as in efficacy of per-label recommended doses can be evidenced among individual ARBs. Olmesartan efficacy was consistently at the highest end of the range of efficacy of ARBs studied.

Characterization of inhibition of platelet function by paracetamol and its interaction with diclofenac in vitro

BACKGROUND

Paracetamol (acetaminophen) is an effective analgesic and a weak inhibitor of cyclo-oxygenase (COX). Clinically paracetamol is often used together with traditional NSAIDs, which are strong inhibitors of COX. We studied binding of paracetamol to COX and its action on platelet function together with diclofenac.

METHODS

Blood was collected from healthy donors and platelet function was assessed by photometric aggregometry, a platelet function analyser (PFA-100, Dade Behring, Deerfield, IL) and by measuring the release of thromboxane B(2) (TxB(2)), the stable metabolite of thromboxane A(2), after addition of paracetamol (10-80 microg ml(-1)). A concentration-inhibition relationship was established and the inhibition coefficient (K(i)) demonstrating 50% binding to COX was determined using a Schild-plot. Interaction of paracetamol (5-20 microg ml(-1)) and diclofenac (0.1-0.8 microg ml(-1)) was determined and an isobolographic analysis was performed.

RESULTS

Paracetamol added to platelet-rich plasma (PRP) caused a concentration-dependent inhibition of platelet function. Photometric aggregometry and TxB(2) release was significantly inhibited by paracetamol from 10 microg ml(-1) onwards. The PFA-100 closure time was significantly prolonged by paracetamol at a high concentration only. K(i) was 15.2 microg ml(-1) with a 95% confidence interval of 11.8-18.6 microg ml(-1). Inhibition of aggregation by diclofenac was augmented by paracetamol. Isobolographic analysis showed synergism.

CONCLUSIONS

The 95% confidence interval of K(i) equals the antipyretic plasma concentration of paracetamol, i.e. 10-20 microg ml(-1). High doses of paracetamol and a combination of diclofenac and paracetamol cause platelet inhibition and thus may increase risk of surgical bleeding.

Candesartan Treatment for Peripheral Occlusive Arterial Disease after Stent Angioplasty

OBJECTIVES

In this prospective, double-blind, placebo-controlled study we observed the influence of treatment with candesartan 8mg on restenosis rates after stent implantation into the femoral artery 6 months after percutaneous transluminal angioplasty (PTA). We hypothesised that angiotensin II type 1 (AT1)-receptor blockade with candesartan would reduce restenosis rates by reducing angiotensin II-mediated intima hyperproliferation within the stented vessel segment in patients with peripheral occlusive disease.

PATIENTS AND METHODS

Eighty-seven patients with peripheral occlusive arterial disease stage IIb who had been successfully treated with PTA and stent implantation were randomised to receive orally either candesartan 8mg (n = 44) or placebo (n = 43). Follow-up included evaluation of the degree of stenosis and thickness of the intima-media complex (primary endpoint). In addition, thickness of the interventricular septum, crurobrachial pressure ratios, and pain-free walking distance were determined (secondary endpoints).

RESULTS

The degree of stenosis after 6 months was not significantly different between the groups studied (35.9 +/- 39.6% for candesartan vs 36.0 +/- 38.4% for placebo). Relevant restenosis including stent occlusions was found in nine patients (20.5%) in the candesartan group and in ten patients (23.3%) in the placebo group. The thickness of the intima-media complex 6 months after stent implantation was 1.60 +/- 0.32mm in the candesartan group and 1.64 +/- 0.32mm in the placebo group (not significant). There were no differences in secondary endpoints between the treatment groups. Controls after 3 months (20.9 +/- 33.6% for candesartan vs 27.6 +/- 38.3% for placebo; p = 0.39) and 9 months (44.1 +/- 40.8% for candesartan vs 47.7 +/- 37.2% for placebo; p = 0.67) of therapy revealed a lower degree of stenosis in patients treated with candesartan.

CONCLUSIONS

Although not significant, candesartan treatment tended to improve the prognostic benefits after stent implantation, suggesting that an antiproliferative effect after stenting may need higher doses than an antihypertensive effect of the drug. This hypothesis requires confirmation in further prospective studies with higher daily doses of candesartan, which are already in progress.