Lotensin scientific update |
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Hypertension. 2006 Sep 18;
Barker TA, Massett MP, Korshunov VA, Mohan AM, Kennedy AJ, Berk BC.
Cardiovascular Research Institute and Departments of Medicine and Biostatistics, University of Rochester, Rochester, NY.
Angiotensin II Type 2 Receptor Expression After Vascular Injury. Differing Effects of Angiotensin-Converting Enzyme Inhibition and Angiotensin Receptor Blockade.
It has been suggested that the effects of angiotensin II type 1 receptor (AT1R) blockers are in part because of angiotensin II type 2 receptor (AT2R) signaling. Interactions between the AT2R and kinins modulate cardiovascular function. Because AT2R expression increases after vascular injury, we hypothesized that the effects on vascular remodeling of the AT1R blocker valsartan and the ACE inhibitor benazepril require AT2R signaling through the bradykinin 1 and 2 receptors (B1R and B2R). To test this hypothesis, Brown Norway rats were assigned to 8 treatments (n=16): valsartan, valsartan+PD123319 (AT2R inhibitor), valsartan+des-arg(9)-[Leu(8)]-bradykinin (B1R inhibitor), valsartan+HOE140 (B2R inhibitor), benazepril, benazepril+HOE140, amlodipine, and vehicle. After 1 week of treatment, carotid balloon injury was performed. Two weeks later, carotids were harvested for morphometry and analysis of receptor expression by immunohistochemistry and Western blotting. Valsartan and benazepril significantly reduced the intima:media ratio compared with vehicle. Blockade of AT2R, B1R, or B2R in the presence of valsartan prevented the reduction seen with valsartan alone. B2R blockade inhibited the effect of benazepril. Injury increased AT1R, AT2R, B1R, and B2R expression. Treatment with valsartan but not benazepril significantly increased intima AT2R expression 2-fold compared with vehicle, which was not reversed by inhibition of AT2R, B1R, and B2R. Functionally, valsartan increased intimal cGMP levels compared with vehicle, and this increase was inhibited by blocking the AT2R, B1R, and B2R. Results suggest that AT2R expression and increased cGMP represent a molecular mechanism that differentiates AT1R blockers, such as valsartan, from angiotensin-converting enzyme inhibitors like benazepril.
Am J Kidney Dis. 2004 Feb;43(2):260-8.
Rutkowski P, Tylicki L, Renke M, Korejwo G, Zdrojewski Z, Rutkowski B.
Department of Nephrology, Transplantology, and Internal Medicine, Medical University of Gdansk, Gdansk, Poland.
Low-dose dual blockade of the renin-angiotensin system in patients with primary glomerulonephritis.
BACKGROUND: Treatment with agents interfering with the renin-angiotensin system retards the progressive course of proteinuric chronic renal disease. However, because of unwanted effects associated with such therapy, some patients cannot be treated with these drugs at all or may be administered only very small doses. To find an optimal nephroprotective strategy for these patients, we compared antiproteinuric effects of combination therapy with an angiotensin-converting enzyme inhibitor and angiotensin II type 1 receptor antagonist in very small doses with treatment with either agent alone at greater, but not maximal, doses. We compared the concomitant use of benazepril, 5 mg, and losartan, 25 mg, and monotherapy with these agents in doses 2-fold greater. METHODS: This is a randomized, open, crossover study of 3 treatments in 3 periods of 4 months each. Twenty-four patients with primary glomerulonephritis and nonnephrotic proteinuria, recognized previously as not able to be administered high doses of drugs from these classes, completed the protocol. RESULTS: Combined therapy decreased 24-hour proteinuria (-45.54% versus baseline) more effectively than either losartan (-28.17%; analysis of variance, P < 0.01) or benazepril (-20.19%; analysis of variance, P < 0.001) alone. Subgroup analysis showed that antiproteinuric effects of combination therapy, as well as losartan or benazepril alone, were significantly greater in patients with basal proteinuria greater than 2 g/24 h than in those with proteinuria less than this value (P < 0.001, P < 0.01, and P < 0.05, respectively). All therapies significantly decreased blood pressure (BP) compared with baseline, but there were no differences between treatments in BP changes. CONCLUSION: The study shows that combination therapy with very small doses of losartan and benazepril was more effective in reducing proteinuria than greater doses of either agent in monotherapy, and this greater antiproteinuric efficacy was independent of changes in BP.
Adv Perit Dial. 2003;19:10-4.
Ishida Y, Tomori K, Nakamoto H, Imai H, Suzuki H.
Department of Nephrology, Saitama Medical School, Saitama, Japan.
Effects of antihypertensive drugs on peritoneal vessels in hypertensive dogs with mild renal insufficiency.
The transport capacity of any membrane depends on its surface area and permeability. In addition, peritoneal capillaries are probably barriers to solute transport. Although no decisive use of antihypertensive drugs has been reported in continuous ambulatory peritoneal dialysis (CAPD) patients with hypertension, those drugs are known to have various effects on vessels. In the present study, we used a charge-coupled-device (CCD) camera in renovascular hypertensive dogs with mild renal insufficiency to investigate the effects of various antihypertensive drugs on the peritoneal capillaries. Renovascular hypertension was induced in the dogs by placing silver clips on both renal arteries to create 90% occlusion. After confirmation of elevation of blood pressure (usually 20 days after the operation), each dog's abdomen was opened while the animal was under general anesthesia. Using a CCD camera, the diameters of the small arteries of the peritoneum were measured after 3 days' oral administration of a placebo (n = 5); or of 8 mg CS866, a selective angiotensin II type 1 receptor blocker (n = 5); or of 10 mg benazepril, an angiotensin-converting enzyme inhibitor (n = 5); or of 10 mg amlodipine, a calcium antagonist (n = 5). In dogs receiving CS866, blood pressure decreased to 128 +/- 6 mmHg from 160 +/- 6 mmHg (p < 0.01). A similar decrease in blood pressure was observed with the use of the other drugs. The diameter of the small vessels increased by 28% +/- 6% in dogs receiving CS866 and by 24% +/- 5% in dogs receiving benazepril, as compared with 3% +/- 3% in dogs receiving the calcium antagonist. These data clearly demonstrate that blockade of the renin-angiotensin system produces an increase in solute clearance in hypertensive dogs with mild renal insufficiency and that such blockade may be applicable as therapy for hypertensive patients on CAPD.
J Chromatogr B Analyt Technol Biomed Life Sci. 2005 Jan 25;814(2):303-8.
Xiao W, Chen B, Yao S, Cheng Z.
Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Hunan Normal University), Ministry of Education, Hunan Normal University, Changsha 410081, PR China.
Simultaneous determination of benazepril hydrochloride and benazeprilat in plasma by high-performance liquid chromatography/electrospray-mass spectrometry.
An analytical method for simultaneous determination of benazepril and its active metabolite, benazeprilat, in human plasma by high-performance liquid chromatography/electrospray-mass spectrometry was developed and validated. Rutaecarpine was selected as the internal standard. The separation was achieved on a C(18) column with acetonitrile and aqueous solution (0.1% formic acid) as mobile phase with a gradient mode. The quantification of target compounds was using a selective ionization recording at m/z 425.5 for benazepril, m/z 397.5 for benzeprilat and m/z 288.3 for rutaecarpine. The correlation coefficients of the calibration curves were better than 0.992 (n = 6), in the range of 6.67-666.67 ng/ml for benazepril and benazeprilat. The inter- and intra-day accuracy, precision, linear range had been investigated in detail. The method can be used to assess the bioavailability and pharmacokinetics of the drug.
Lotensin description...
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Drug category:Hypotensive agents
 Lotensin scientific update
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