Renal effects of angiotensin converting enzyme inhibitors in hypertension

Regression of left ventricular hypertrophy and improvement of renal hemodynamics in hypertensive patients treated with quinapril

Of 17 patients with mild to moderate essential hypertension, 8 showed echocardiographic evidence of left ventricular hypertrophy. Cardiac and renal function evaluated by glomerular filtration rate (GFR) were studied in all patients before and after 20 weeks of quinapril treatment. Systolic pressure decreased from 174.7 +/- 16.7 to 131.7 +/- 7.7 mmHg (p < .0001) and diastolic pressure decreased from 101.8 +/- 9.8 to 80 +/- 4.3 mmHg (p < .0001). Left ventricular mass index decreased in the eight patients with left ventricular hypertrophy (p < .01). Basal values of GFR were lower than normal in 41% of all patients; GFR increased significantly after 20 weeks of treatment (from 96.5 +/- 32.3 to 108.6 +/- 31.12 ml/min, p < .01); it decreased in only one patient. Patients reported few adverse effects to quinapril, and no important clinical laboratory abnormality was observed. Quinapril not only lowered arterial pressure, but it had a distinct effect on regression of left ventricular hypertrophy and favorable effects on renal function.

Renal and hormonal responses to repeated treatment with enalapril in non-azotemic cirrhosis with ascites

Since a single dose of the angiotensin-converting enzyme inhibitor enalapril was shown to cause natriuresis in cirrhosis in a previous study, we investigated whether repeated doses of this substance would sustain a favorable renal effect in cirrhosis. Ten milligrams of enalapril maleate were administered once a day for 8 days to ten patients with non-azotemic cirrhosis and ascites. Enalapril reduced blood pressure significantly at 4 to 12 h (systolic blood pressure) and 2, 6, and 8 h (diastolic blood pressure) on day 2, compared to pretreatment (day 0) values, but this depressor effect decreased on day 8. No change in heart rate could be detected. Enalapril significantly suppressed serum angiotensin-converting enzyme activity and plasma aldosterone concentration (p < 0.001 to 0.01), which were elevated prior to treatment, with pretreatment values of 25.8 +/- 1.8 IU/l for serum angiotensin-converting enzyme activity and 241 +/- 67 pg/ml for plasma aldosterone concentration. This drug caused a 12 to 24% increase (p < 0.05 to 0.01) in mean daily urinary volume and a 40 to 54% increase (p < 0.001 to 0.01) in mean daily urinary sodium excretion from the respective pretreatment baselines during the 8-day period. Creatinine clearance was improved (p < 0.05) by the treatment, with mean improvement values from 24 to 34% above the pretreatment value of 47.4 +/- 4.3 ml/min.(ABSTRACT TRUNCATED AT 250 WORDS)

Renal effects of antihypertensive medications: an overview

A variety of antihypertensive agents are available for management of elevated arterial pressure. Although these agents all effectively lower arterial pressure, they have somewhat diverse renal hemodynamic profiles. This report reviews the various similarities and differences in renal hemodynamic profiles among the different antihypertensive agents.

Short- and long-term effects of spirapril on renal hemodynamics in patients with essential hypertension

Sixteen essential hypertensive patients were entered into a protocol assessing the effect of Spirapril, an angiotensin-converting enzyme (ACE) inhibitor, on blood pressure, the renin-aldosterone system, and renal function. Specifically monitored before, during 6 weeks, and 6 months of Spirapril therapy were plasma renin activity, plasma aldosterone, serum ACE, the renal clearances of creatinine, inulin, and para-aminohippurate, and urinary albumin excretion. Blood pressure was well controlled. Spirapril stimulated plasma renin activity and suppressed ACE throughout the entire protocol. Renal clearances were unchanged. Renal vascular resistance was decreased. Urinary albumin excretion was decreased. The authors conclude that the ACE inhibitor, Spirapril, when used as an effective antihypertensive agent, preserves renal function, lowers renal vascular resistance, and decreases urinary albumin excretion.

Effects of inhibitors of angiotensin-converting enzyme on regional hemodynamics

Inhibitors of angiotensin-converting enzyme (ACE) exert favorable regional hemodynamic effects at various sites. In patients with essential hypertension, ACE inhibitors reduce renal vascular resistance while enhancing renal blood flow, glomerular filtration rate, and acute and sustained natriuresis. Whereas these agents may either reduce or have no effect on hepatic blood flow, they are associated with reduced splanchnic resistance. ACE inhibitors reduce total peripheral resistance and may maintain limb blood flow. In normal subjects, they augment blood flow to skeletal muscle and skin and reduce peripheral resistance in vessels supplying these regions. ACE inhibitors appear to exert a vasodilatory effect on large arteries as well as arterioles. Dilatation is often accompanied by significant improvements in arterial compliance, possibly due to direct effects of the renin-angiotensin system on the arterial wall. Reduction of blood pressure is generally not accompanied by reduced cerebral blood flow. Enhanced tissue effects of newer ACE inhibitors such as quinapril may result in improved regional hemodynamic effects.

Enalapril. A reappraisal of its pharmacology and therapeutic use in hypertension

Enalapril, an angiotensin converting enzyme (ACE) inhibitor usually administered orally once daily, decreases blood pressure by lowering peripheral vascular resistance without increasing heart rate or output. It is effective in lowering blood pressure in all grades of essential and renovascular hypertension. Patients not responding adequately to enalapril monotherapy usually respond with the addition of a thiazide diuretic (or a calcium antagonist or beta-blocker), and rarely require a third antihypertensive agent. Enalapril is at least as effective as other established and newer ACE inhibitors, and members of other antihypertensive drug classes including diuretics, beta-blockers, calcium antagonists and alpha-blockers, but therapy with enalapril may be less frequently limited by serious adverse effects or treatment contraindications than with other drug classes. The most frequent adverse effect limiting all ACE inhibitor therapy in clinical practice is cough. This favourable profile of efficacy and tolerability, and the substantial weight of clinical experience, explain the increasing acceptance of enalapril as a major antihypertensive treatment and supports its use as logical first-line therapeutic option.

Immediate and short-term cardiovascular effects of fosinopril, a new angiotensin-converting enzyme inhibitor, in patients with essential hypertension

Immediate and short-term cardiovascular effects of a new angiotensin-converting enzyme inhibitor, fosinopril, were assessed in 10 patients with mild to moderate essential hypertension. Administration of a 10 mg oral dose of fosinopril reduced mean arterial pressure (p less than 0.001) as a result of a 24% fall in total peripheral resistance (p less than 0.001). Short-term therapy (12 weeks) maintained the decrease in mean arterial pressure (p less than 0.05) by decreasing total peripheral resistance (p less than 0.01), without reflexive cardiac stimulation or expanding intravascular volume. Renal vascular resistance decreased (p less than 0.05) while renal blood flow, glomerular filtration rate and filtration fraction remained unchanged. The response pattern to mental, isometric and orthostatic stress was similarly unchanged. Left ventricular mass diminished by 11% (p less than 0.01); myocardial contractility was unaffected. Afterload was reduced (p less than 0.05), and velocity of circumferential fiber shortening and stroke volume increased (p less than 0.05). Thus, arterial pressure reduction produced by fosinopril was associated with improved systemic and renal hemodynamics and reduced left ventricular mass.

Angiotensin-converting enzyme inhibitors and renal function

The effects of angiotensin-converting enzyme (ACE) inhibitors on renal hemodynamics vary widely depending on the preexisting physiologic and pathologic state of the kidneys. Although some studies of ACE inhibitors in primary essential hypertension have demonstrated increases in glomerular filtration rate (GFR) and effective renal plasma flow in patients with renal impairment, other studies have not shown these same beneficial results. The difference may involve the choice of ACE inhibitor used in the investigations, but controlled comparison trials are needed to determine whether this is the case. The use of ACE inhibitors in renovascular hypertension remains controversial. ACE inhibition can interfere with the autoregulation of GFR mediated by angiotensin II and may lead to deterioration of renal function, especially in patients with bilateral renal artery stenosis or stenosis of a solitary kidney. Additionally, ACE inhibitors have been shown to cause a decline in GFR in the kidney affected by the stenosis, whether or not clinically apparent renal insufficiency occurs. Although the functional impairment associated with ACE inhibitors in renal artery stenosis has generally been reversible following removal of the drug, the consequences of a long-term reduction in GFR are unknown. Treatment of stable congestive heart failure (CHF) with ACE inhibitors can result in enhancement of GFR and reduction of sodium and fluid retention, thus improving the clinical state. However, in patients with decompensated cardiac failure, renal perfusion pressures may already be at or near the autoregulatory breakpoint and ACE inhibition may cause deterioration of renal function. In general, ACE inhibitors can be used safely in CHF if they are initiated cautiously, with adjustment of ACE inhibitor and diuretic dosages to avoid systemic hypotension and sodium and fluid depletion. In studies comparing the agents, enalapril and lisinopril have both been shown to cause higher incidences of renal function deterioration than has captopril. These findings suggest that the more complete or sustained ACE inhibition seen with the longer-acting agents may be detrimental to renal function in patients with CHF. The use of ACE inhibitors in the treatment of proteinuria is the newest area of research with these agents. At present it appears that ACE inhibitors reduce urinary protein excretion the most effectively in diabetic patients with mild proteinuria and in hypertensive patients with renal insufficiency and proteinuria due to glomerular disorders. More study is needed to determine whether these agents can reduce the rate of renal failure progression and to define the patient populations expected to benefit most.(ABSTRACT TRUNCATED AT 400 WORDS)

Effect of benazepril monotherapy in subjects with hypertension associated with renal dysfunction

Nine hypertensive patients with mild to moderate renal dysfunction were entered into a protocol to assess the blood pressure, humoral and renal effects of the angiotensin converting enzyme inhibitor, Benazepril (CGS14824A, 2 to 20 mg twice daily) in patients with hypertension and moderate renal insufficiency (mean creatinine clearance 56 ml/min/1.73 m2). Specifically monitored, prior to and following 12 weeks of Benazepril monotherapy, were plasma renin activity and plasma aldosterone, the clearances of creatinine, Tc99m-diethylenetriaminepentaacetic acid (TC99m-DTPA) and para-amino-hippurate, and the 24-hour urinary excretion of protein. Blood pressure was well controlled. Plasma renin activity was stimulated, and plasma aldosterone was suppressed. Mean serum potassium increased from 3.9 to 4.2 mEq/L. Benazepril monotherapy had no adverse renal hemodynamic effect. Benazepril appears to be an effective antihypertensive agent in hypertensive patients with moderately impaired renal function.

New insights and new approaches for the treatment of essential hypertension: selection of therapy based on coronary heart disease risk factor analysis, hemodynamic profiles, quality of life, and subsets of hypertension

The pharmacologic therapy of mild primary hypertension (diastolic blood pressure less than 105 mm Hg) has effectively reduced hypertensive arteriolar end organ disease such as cerebrovascular accidents, congestive heart failure, and nephropathy, but there has been no convincing evidence that coronary heart disease (CHD) or its complications, acute myocardial infarction or angina, have been reduced. The risks of therapy with certain antihypertensive drugs may outweigh their treatment benefits as it relates to CHD. The optimal treatment strategy should be to reduce all CHD risk factors, reverse the hemodynamic abnormalities present by lowering the systemic vascular resistance (SVR), preserving cardiac output (CO) and perfusion, and to select the best antihypertensive drug for concomitant medical diseases or problems while maintaining a good quality of life. Antihypertensive drugs that have favorable or neutral effects on CHD risk factors include alpha blockers, calcium channel blockers, central alpha agonists, and angiotensin-converting enzyme inhibitors. On the other hand, diuretics and beta blockers without intrinsic sympathomimetic activity have unfavorable effects on many CHD risk factors. Baseline and serial evaluation of the effects of these drugs on serum lipids, lipid subfractions, glucose, uric acid, electrolytes, exercise tolerance, left ventricular hypertrophy, blood pressure, SVR, CO, perfusion, concomitant diseases, and side effects is necessary to evaluate overall cardiovascular risk.

Effect of lisinopril monotherapy on renal hemodynamics

Nineteen essential hypertensive patients were entered into a protocol to assess the BP, humoral and renal effects of the angiotensin converting enzyme inhibitor, lisinopril (MK 521, 20 to 80 mg once daily), administered for 52 weeks. Specifically monitored prior to, and following 12 and 52 weeks of lisinopril monotherapy were plasma renin activity and plasma aldosterone, the clearances of creatinine, inulin and para-aminohippurate, and the 24-hour urinary excretion of protein. BP was well controlled. Plasma renin activity was stimulated, and plasma aldosterone was suppressed throughout the entire protocol. In contrast to the reported short-term and long-term renal effects of enalapril, lisinopril (a lysine analog of enalapril) had no short-term effect on renal function: glomerular filtration rate, effective renal plasma flow, filtration fraction (FF), renal vascular resistance (RVR), and protein excretion were all unchanged. However, following long-term therapy, both FF and RVR were decreased. Lisinopril appears to convey no specific renal pharmacological benefit.

Pathophysiology of increased urinary N-acetyl-beta-D-glucosaminidase activity in human hypertension: effect of cilazapril therapy

To investigate the pathophysiology of elevated urinary N-acetyl-beta-D-glucosaminidase (NAG) activity in human hypertension, total and fractional urinary NAG activities were correlated with Li clearance, a measure of proximal renal tubular Na reabsorption, in 15 white hypertensive subjects, aged 56 years, and in 13 normotensive control subjects. In 11 hypertensive subjects, the measurements were repeated after 2 months of antihypertensive therapy with the converting enzyme inhibitor cilazapril (2.5 or 5.0 mg daily). Urinary NAG activity was increased in hypertensives and correlated directly with Li clearance in both hypertensive and normotensive subjects. Li clearance and urinary NAG activity were reduced by antihypertensive therapy. The findings indicate an inverse correlation between urinary NAG activity and proximal renal tubular Na reabsorption, suggesting that NAG is reabsorbed in the proximal renal tubules with Na and other proteins. High Li clearance and urinary NAG activity in hypertension are in part functional and, therefore, reversible disturbances of renal function.

Effects of antihypertensive therapy on kidney function in diabetic patients

Diabetic nephropathy is one of the major long term complications responsible for mortality in diabetes mellitus. While strict metabolic control of diabetes probably has a positive influence on kidney disease, most evidence supports the view that the process leading to end-stage renal failure has become independent of the metabolic disturbances of diabetes, and that haemodynamic factors in established nephropathy have become the predominant causes of progression of renal damage. In particular, increased intraglomerular pressure is thought to play a crucial part in the development of diabetic nephropathy. Therefore, drugs that can reduce intraglomerular pressure are of interest in treatment of hypertension in diabetic patients. The angiotensin-converting enzyme (ACE) inhibitors have been shown to reduce intraglomerular pressure in animal studies, and the use of these drugs to treat insulin-dependent diabetics with hypertension has produced a reduction in the rate of decline of glomerular filtration rate. Although some beta-blockers can also have beneficial effects on renal function, they may produce unwanted metabolic effects. Thus the ACE inhibitors seem to be the most suitable antihypertensive drugs for diabetic patients.