Effect of the angiotensin-converting-enzyme inhibitor benazepril on the progression of chronic renal insufficiency. The Angiotensin-Converting-Enzyme Inhibition in Progressive Renal Insufficiency Study Group

Hypertension in special populations

This article discusses various aspects of hypertension in selected special populations. The groups discussed herein are children, pregnant women, African Americans, persons with kidney insufficiency, kidney transplant survivors, and persons with diabetes mellitus. These groups present unique epidemiological, diagnostic and therapeutic challenges for the practitioner. The detection of reduced kidney function merits special attention since it attenuates the blood pressure response to antihypertensive therapy, affects therapeutic decision-making, is both a cause and consequence of poorly controlled hypertension, often lurks undetected, and is excessively prevalent in some special populations.

Class benefits of AT(1) antagonists in Type 2 diabetes with nephropathy

Diabetes mellitus has reached epidemic proportions in many countries and is the most common cause of end stage renal disease (ESRD). The angiotensin II receptor-1 (AT(1)) antagonists losartan and irbesartan have recently been evaluated as renoprotective agents in large clinical trials of patients with Type 2 diabetes and nephropathy. In the Reduction of End points in Non-insulin-dependent diabetes mellitus with the Angiotensin II Antagonist (RENAAL) study, losartan decreased the number of patients reaching the primary end point of a composite of measures of neuropathy. The relative risk reduction was approximately 15% with losartan and this was due to a reduction in both the doubling of creatinine concentration (25%) and of ESRD (28%) but not in death. In the Irbesartan Diabetic Nephropathy Trial (IDNT), the beneficial effect of irbesartan was mainly against the doubling of the baseline creatinine concentration (37% risk reduction) but there was also a 20% reduction in the onset of ESRD. Irbesartan had no effect on mortality. Beneficial effects occurred in addition to blood pressure being controlled by agents other than the AT(1) antagonists. These clinical trials suggest that there may be a class renoprotective action with AT(1) antagonists, although the mechanism is not clear. Patients with Type 2 diabetes and nephropathy should receive either an AT(1) antagonist or the angiotensin converting enzyme inhibitor ramipril to ensure renoprotection.

Kidney and hypertension

There is a unique relationship between the kidney and blood pressure (BP): on the one hand, renal dysfunction and particularly renal disease cause an increase in BP, while on the other hand, high BP accelerates loss of function of the diseased kidney. Transplantation studies, both in experimental animals and humans, documented that "blood pressure goes with the kidney," a normotensive recipient of a kidney genetically programmed for hypertension (HT) will develop HT, while conversely hypertensive patients with renal failure receiving the kidney of a normotensive donor may develop normotension. Family studies showed higher BP values and more frequent HT in first degree relatives of patients with primary glomerulonephritis or diabetic nephropathy, both type 1 and type 2. The notion that HT accelerates the loss of renal function has been proposed at the turn of the century, but definite evidence by observational and interventional studies has only been provided in the last two decades. The issue has been much confounded by the mistaken believe that damaged kidneys require higher BP values in order to function properly. The mechanisms of BP increase in renal disease comprise: salt retention, inappropriate activity of the renin-angiotensin system (RAS) and of the sympathetic nerve system as well as impaired endothelial cell-mediated vasodilatation. There is ample evidence both in primary renal disease (AIPRI and REIN trials) and in nephropathy of type 1 and type 2 diabetes (IDNT, RENAAL) that pharmacological blockade of the RAS by angiotensin-converting enzyme inhibitors or angiotensin II type 1 receptor blockers has BP-independent renoprotective effects. More recently, it has also been shown that blockade of the sympathetic nerve system has BP-independent effects on albuminuria and on glomerulosclerosis.

Regional variation in end-stage renal disease

Regional variations in end-stage renal disease have been found within a country, even within a race. Since diabetic nephropathy is the leading cause of end-stage renal disease in developed countries, first of all, regional differences in diabetic nephropathy must be considered. Although the incidence of end-stage renal disease due to diabetic nephropathy has been found to differ among different areas within a country, there are no data on regional variations in the incidence of type II diabetes or diabetic nephropathy without renal failure. Such regional variations could hardly be explained by local differences in gene pools alone, which suggests an important role of environmental factors. It is not clear at present how regional variations in the incidence of end-stage renal disease are generated. If we can identify the factors that contribute to the regional differences, we can take these into account in future treatment strategies for renal disease. Thus, much effort is required in further analysis of regional differences in end-stage renal disease dynamics.

Does non-malignant hypertension cause renal insufficiency? Evidence-based perspective

While it is clear that malignant hypertension damages the kidneys, the question of whether non-malignant hypertension actually causes renal insufficiency remains controversial. A recent meta-analysis of 10 randomized controlled trials of antihypertensive drug therapy showed that patients randomized to antihypertensive therapy (or more-intensive therapy) did not show a significant reduction in their risk of developing renal dysfunction (relative risk, 0.97; 95% confidence interval, 0.78-1.21; P=0.77). A review of the totality of the evidence shows that there is relatively weak support for the thesis that non-malignant hypertension itself is an important de-novo cause (initiator) of renal insufficiency (as opposed to being a promoter of existing renal disease, which is a well established fact). Failure to evaluate the possibility that pre-existing renal disease could explain any observed association between elevated blood pressure and subsequent loss of renal function is an important limitation of published studies.

Slowing the progression of renal failure

In recent years several multicentric prospective studies have demonstrated the efficacy of some therapeutic measures to slow the progression of renal diseases. Inhibition of renin-angiotensin system (RAS) both by ACE inhibitors (ACEI) and angiotensin II receptor antagonists (ARA) is probably the strongest therapeutic alternative: The antiproteinuric effect of these drugs is an excellent surrogate marker and a predictor of the beneficial influences on the progression of renal failure. The type of renal disease, an inadequate control of blood pressure, and the presence of obesity may counteract the beneficial influences of RAS inhibition, whereas early treatment of all patients with significant proteinuria before the appearance of renal insufficiency and combined therapy with an ACEI and an ARA may augment it. Dietary protein restriction is a classic treatment of chronic renal insufficiency whose effectiveness has been validated by multicentric studies. However, a poor compliance of the patient and the risk of malnutrition with very strict protein restriction could limit the benefits of this treatment. Treatment of hyperlipidemia, prevention of obesity, avoidance of smoking, and regular physical exercise are interventions whose therapeutic potential is progressively recognized, particularly in type 2 diabetic nephropathy. Early correction of anemia may contribute to the slowing of renal disease progression. Although further studies are required, the accumulated evidence and the likelihood of additive beneficial effect of these therapeutic measures advise their combined implementation in patients with chronic renal diseases.

FK506 ameliorates proteinuria and glomerular lesions induced by anti-Thy 1.1 monoclonal antibody 1-22-3

BACKGROUND

We have previously reported that CD4 T lymphocytes and their cytokines contribute to development of Thy 1.1 glomerulonephritis (GN). FK506 is reported to suppress the production of Th1 cytokines. The aims of this study were to elucidate the role of Th1 cytokines on mesangial alteration and to examine whether FK506 is available for therapy of mesangial proliferative GN.

METHODS

The effects of daily treatments of FK506 from day -5 and from day +1 of Thy 1.1 GN induction on glomerular alterations were analyzed.

RESULTS

FK506 treatment with 1.0 and 0.3 mg/kg body weight (BW) daily from day 1 to day 4 significantly reduced the glomerular expression of mRNA for interferon-gamma (IFN-gamma; 1.0 mg/kg BW FK506, 32.4% to the placebo group, P < 0.01) and IL-2 (55.6%, P < 0.01) on day 5. FK506 treatment from day -5 of GN induction reduced proteinuria and glomerular alteration in a dose-dependent manner. Although no side effects were detected in rats with 0.3 mg/kg BW of FK506 treatment from day +1, the treatment also ameliorated proteinuria (day 14, 3.7 +/- 0.89 vs. 19.8 +/- 12.3 mg/100 g BW/day P < 0.05) and glomerular alterations [total cell number, 63.1 +/- 3.1 vs. 80.2 +/- 7.4, P < 0.01; matrix expansion, 0.90 +/- 0.30 vs. 1.34 +/- 0.27, P < 0.05; alpha-smooth muscle actin (alphaSMA) expression; 1.20 +/- 0.12 vs. 1.96 +/- 0.29, P < 0.01] on day 14.

CONCLUSION

Th1 cytokines may play an important role in the development of mesangial proliferative glomerulonephritis, and could be targets for therapy. FK506 might be available for clinical use.

Reduction of proteinuria; combined effects of receptor blockade and low dose angiotensin-converting enzyme inhibition

OBJECTIVE

Angiotensin-converting enzyme inhibitors (ACEI) show an antiproteinuric and thus nephroprotective effect in patients suffering from glomerulonephritis. Angiotensin II-receptor-antagonists (AT1RA) are also efficacious in reducing proteinuria. The study was performed to investigate the antiproteinuric effect of AT1RA candesartan in patients diagnosed with chronic glomerulonephritis by biopsy, and who were already being treated with an ACEI.

METHODS

A total of 12 patients with a persistent proteinuria of at least 1 g/day who were already being treated with an ACEI for more than 3 months were included. The study was performed using a double-blind, placebo-controlled and randomized method with two treatment periods of 8 weeks (placebo or candesartan 8 mg/day) and a wash-out period of 4 weeks in between. Glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) were measured by inulin- and PAH-clearances at the beginning and the end of each treatment period.

RESULTS

Proteinuria significantly decreased from 2 +/- 0.4 g/day to 1.3 +/- 0.3 g/day (P < 0.05) with the addition of candesartan treatment, whereas it remained unchanged (from 1.8 +/- 0.3 g/day to 1.9 +/- 0.3 g/day) under placebo. GFR (candesartan: from 66 +/- 13 to 58 +/- 11 ml/min per 1.73 m2, placebo: from 64 +/- 11 to 62 +/- 13 ml/min per 1.73 m2) and ERPF (candesartan: from 329 +/- 44 to 304 +/- 37 ml/min per 1.73 m2, placebo: from 362 +/- 48 to 315 +/- 46 ml/min per 1.73 m2) did not alter significantly after 8 weeks of treatment. The addition of candesartan treatment significantly reduced systolic blood pressure (from 129 +/- 3 to 123 +/- 2 mmHg, P < 0.05) and diastolic blood pressure (from 79 +/- 2 to 76 +/- 2 mmHg, P < 0.05) compared with placebo (systolic: 128 +/- 3 to 127 +/- 3 mmHg, diastolic: 79 +/- 2 to 79 +/- 2 mmHg).

CONCLUSION

Candesartan promotes a complementary antiproteinuric and a small antihypertensive effect after a treatment period of 8 weeks in patients with chronic glomerulonephritis when given in conjunction with an ACEI. Renal hemodynamics did not vary significantly.

Chronic thrombotic microangiopathy associated with antineoplastic therapy with minimal hematologic effects

OBJECTIVE

To describe 6 patients who developed progressive renal failure and renal thrombotic microangiopathy (TM) not accompanied by the characteristic hematologic disturbances of TM syndromes.

PATIENTS AND METHODS

Portions of renal biopsy specimens from each patient were examined by light and electron microscopy for histopathologic evidence of TM. Antecedent clinical events, laboratory evidence of hemolysis and thrombocytopenia, and clinical outcome were documented. Medical records were reviewed and clinical data, including laboratory values, treatment, and outcome, were recorded.

RESULTS

In each case, a slowly progressive uremia evolved after radiation and/or chemotherapy without laboratory evidence of acute hemolysis or thrombocytopenia. Renal biopsy specimens in all cases showed TM and tubulointerstitial scarring, suggesting both acute and chronic renal injury. Two of the 6 patients underwent plasma exchange therapy without improvement of renal function. Three patients treated with angiotensin-converting enzyme inhibitors for coexisting systemic hypertension remained stable or had mild improvement in renal function.

CONCLUSIONS

A small subset of patients treated for malignancy developed slowly evolving uremia associated with renal TM without marked hematologic abnormalities. In the absence of thrombocytopenia and other typical laboratory findings, the diagnosis of renal TM may be overlooked.

Short-term effects of angiotensin II receptor blockade in patients with primary glomerulonephritis: pilot study

OBJECTIVE

There is evidence that angiotensin II, the main effector of renin-angiotensin system, plays a crucial role in the pathogenesis of chronic renal injury. Angiotensin II type 1 (AT-1) receptor blockers reduce renin-angiotensin system activity by blocking the receptor, the activation of which is responsible for the majority of deleterious angiotensin II effects. The aim of the present study was to investigate renal and metabolic effects of specific AT-1 receptor blocker-losartan in patients with primary glomerulonephritis.

DESIGN

Pilot clinical study.

SETTING

Department of Nephrology, Transplantology and Internal Medicine, Medical University of Gdańsk, Poland.

PARTICIPANTS

Fifteen patients aged 43.3 +/- 11.3 years with primary glomerulonephritis confirmed by renal biopsy were studied.

INTERVENTION

Creatinine clearance, urinary excretion of protein and uric acid, urinary activity of N-acetyl-beta-D-glucosaminidase, and serum concentrations of lipids, protein, and uric acid were evaluated before and after 3 months of losartan (Cozaar; Merck Sharp & Dohme, Harlow, Essex, United Kingdom) treatment at a dose of 25 mg daily.

RESULTS

We found a significant reduction of urinary excretion of protein (P <.008; average, 32%). Results also revealed a decrease of serum uric acid level (P <.01), probably as a consequence of elevated uric acid urinary excretion (P <.09). No significant changes in creatinine clearance, N-acetyl-beta-D-glucosaminidase activity, protein, or lipid levels were observed.

CONCLUSION

We concluded that losartan treatment at a small dose of 25 mg daily produces antiproteinuric effect without adverse effects, notably with no decrease of glomerular filtration, and simultaneously induces beneficial changes in purine metabolism.

Combined therapy of tacrolimus and corticosteroids in cyclosporin-resistant or -dependent idiopathic focal glomerulosclerosis: a preliminary uncontrolled study with prospective follow-up

BACKGROUND

Cyclosporin has improved the outcome for steroid-resistant patients with focal glomerulosclerosis, but there is a proportion of patients that are either cyclosporin-resistant or suffer relapses, needing long-term therapy to sustain the remission. In these cases, preliminary reports suggest that tacrolimus could be an alternative therapy, but to date the evidence is limited to small series of patients with no long-term follow-up.

METHODS

In this study we analysed the efficacy and safety of a combined therapy of tacrolimus and steroids in 25 patients (mean serum creatinine= 1.24+/-0.49 mg/dl; mean proteinuria=10.2+/-9.5 g/day; mean serum albumin=2.4+/-0.58 g/dl) with idiopathic primary focal glomerulosclerosis and proven resistance to or dependence on cyclosporin A.

RESULTS

After a 6 months trial of tacrolimus and steroids, proteinuria decreased in 17 patients (68%) (complete remission in 10 patients (40%), partial remission in two patients (8%) and a moderate reduction in proteinuria to levels <3 g/day was seen in five additional patients (20%)). The only predictor of response to tacrolimus was a previous response to cyclosporin and prednisone, either as a complete or partial remission (remission rate 75% vs 15.3; P=0.036). Mean time to remission was 112+/-24 days. After tacrolimus discontinuation, 13/17 patients (76%) relapsed and were treated with a second trial of tacrolimus for 1 year, achieving complete remission in five patients (38.4%), partial remission in four patients (30.7%) and reduction of proteinuria <3 g/day in four patients (30.7%). After 2 years of follow-up, 12 patients (48%) were on sustained remission. The main side effect was acute reversible nephrotoxicity (40%). Predictors of renal toxicity were age (P=0.037), baseline creatinine (P=0.046) and tacrolimus trough level (P=0.001).

CONCLUSIONS

We conclude that combined therapy of tacrolimus and steroids induce sustained remission of proteinuria in a significant number of patients with idiopathic focal glomerulosclerosis whose disease was not controlled by the standard therapy of steroids and cyclosporin A.

Outcomes of reference pricing for angiotensin-converting-enzyme inhibitors

BACKGROUND

In January 1997, reference pricing for angiotensin-converting-enzyme (ACE) inhibitors for patients 65 years of age or older was introduced in British Columbia, Canada. For medications within a specific class, insurance covers the cost up to the reference price, and patients pay the extra cost of more expensive medications. Although reference pricing may reduce the costs of prescription drugs, there is concern that patients may switch to less effective medications or stop treatment.

METHODS

We analyzed data from the Ministry of Health on all 37,362 residents of British Columbia who were 65 or older and were enrolled in the provincial health insurance program, received ACE inhibitors priced higher than the reference price of $27 a month in 1996, and were potentially affected by the new policy. We identified 5353 residents who switched to an ACE inhibitor not subject to cost sharing during the first six months and compared them with 27,938 residents who received only ACE inhibitors subject to cost sharing.

RESULTS

Reference pricing for ACE inhibitors was not associated with changes in the rates of visits to physicians, hospitalizations, admissions to long-term care facilities, or mortality. The probability of stopping antihypertensive therapy decreased as compared with the probability before the change in policy (relative risk, 0.76; 95 percent confidence interval, 0.65 to 0.89). Eighteen percent of patients who had been prescribed ACE inhibitors subject to cost sharing switched to lower-priced alternatives. As compared with patients who did not switch, those who did had a moderate transitory increase in the rates of visits to physicians (rate ratio, 1.11; 95 percent confidence interval, 1.07 to 1.15) and hospital admissions through the emergency room (rate ratio, 1.19; 95 percent confidence interval, 0.99 to 1.42) during the two months after switching, but not subsequently.

CONCLUSIONS

We found little evidence that when reference pricing for ACE inhibitors was introduced in British Columbia, patients stopped treatment for hypertension or that health care utilization and costs increased.

Combination therapy with benazepril and oral adsorbent ameliorates progressive renal fibrosis in uremic rats

BACKGROUND/AIMS

The administration of an angiotensin-converting enzyme (ACE) inhibitor or an oral adsorbent, AST-120 (Kremezin), prevents the progression of renal failure. This study was designed to determine the additional effects of AST-120 combined with an ACE inhibitor, benazepril, on the progression of renal fibrosis in uremic rats.

METHODS

5/6-nephrectomized uremic rats were divided into control uremic rats (CRF group), benazepril-treated uremic rats (CRF+B group) and uremic rats receiving benazepril and AST-120 (CRF+BK group). After 14 weeks of treatment renal function and pathological changes were investigated.

RESULTS

The progression of renal dysfunction was delayed in both the CRF+B and CRF+BK groups as compared with the CRF group. In the CRF+BK group, the level of serum and urinary indoxyl sulfate and the tubular accumulation of indoxyl sulfate decreased. Both the CRF+B and CRF+BK groups showed lower glomerular sclerosis indices than the CRF group. In the CRF+BK group, but not the CRF+B group, the interstitial fibrosis area and the expression of transforming growth factor (TGF) beta1 and tissue inhibitor of metalloproteinases (TIMP) 1 were decreased as compared with the CRF group. Furthermore, the CRF+BK group showed a smaller interstitial fibrosis area and a lower renal osteopontin expression than the CRF+B group.

CONCLUSION

Combination therapy of benazepril and AST-120 is more effective than benazepril alone in retarding the progression of interstitial fibrosis by reducing the expression of TGF-beta 1, TIMP-1 and osteopontin.

Acute and long-term effects of ACE inhibition on renal haemodynamics in glomerular and interstitial nephropathies

BACKGROUND

Angiotensin-converting enzyme (ACE) inhibitors are the drugs of choice for the treatment of hypertension in patients with non-diabetic nephropathies. However, not every trial has reported better results with ACE inhibitors (ACE-I) than with other drugs. This study investigates whether the acute and chronic effects of ACE inhibition on renal and glomerular haemodynamics are similar in glomerular and interstitial nephropathies.

METHODS

We studied 20 hypertensive patients, on their usual diet, with mild-to-moderate chronic renal failure secondary to non-diabetic nephropathy. After a three-week wash out period, we determined plasma clearances of para-amino-hippurate and inulin before, and after acute oral administration of either enalapril or ramipril. This same test was carried out after one and two years of treatment with the same drug.

RESULTS

Acute ACE inhibition causes a decrease of renal perfusion, glomerular filtration and pressure with an increase of afferent resistances. Long-term ACE inhibition is associated only with a decrease in renal perfusion, with a non-significant tendency to higher filtration fraction and lower afferent resistances. All the renal haemodynamic modifications mentioned above are present only in patients with glomerular diseases.

CONCLUSIONS

Renal and glomerular haemodynamic responses are not similar after acute and chronic ACE inhibition. Only patients with glomerular diseases show acute or long-term responses to ACE inhibition.

Influence of progressive renal dysfunction in chronic heart failure

Chronic heart failure (CHF) is often associated with impaired renal function due to hypoperfusion. Such patients are very sensitive to changes in renal perfusion pressure, and may develop acute tubular necrosis if the pressure falls too far. The situation is complicated by the use of diuretics, ACE inhibitors and spironolactone, all of which may affect renal function and potassium balance. Chronic renal failure (CRF) may also be associated with fluid overload. Anaemia and hypertension in CRF contribute to the development of left ventricular hypertrophy (LVH), which carries a poor prognosis, so correction of these factors is important.

Renin-angiotensin system blockade and the risk of hyperkalemia in chronic hemodialysis patients

BACKGROUND

Blockade of the renin-angiotensin system by angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers can cause hyperkalemia in patients with chronic renal insufficiency who are not on dialysis, but the risk of hyperkalemia in hemodialysis patients is unknown.

SUBJECTS AND METHODS

We conducted a prospective study of 251 adult hemodialysis patients to determine if renin-angiotensin system blockade was associated with hyperkalemia, defined as a predialysis serum potassium concentration of 5.5 mmol/L or higher. Medication use was determined by chart review and patient interview. Predialysis serum potassium concentration was measured monthly.

RESULTS

There were 367 episodes of hyperkalemia during 1877 person-months of follow-up. After adjustment for potential confounding variables and for clustering of episodes by patient, use of an ACE inhibitor or an angiotensin receptor blocker was associated with a significantly higher risk of hyperkalemia (odds ratio [OR] = 2.2; 95% confidence interval [CI]: 1.4 to 3.4). The increased risk of hyperkalemia with renin-angiotensin system blockade was seen in anuric dialysis patients (OR = 2.3; 95% CI: 1.3 to 4.2), as well as those with residual renal function (OR = 2.1; 95% CI: 1.0 to 4.1).

CONCLUSION

The use of ACE inhibitors or angiotensin receptor blockers is independently associated with an increased risk of developing hyperkalemia in chronic hemodialysis patients. The serum potassium concentration should be closely monitored when these medications are prescribed for hemodialysis patients.

Changes in renal resistive index and urinary albumin excretion in hypertensive patients under long-term treatment with lisinopril or nifedipine GITS

INTRODUCTION

Increased renal vascular resistance and microalbuminuria are associated with hypertensive target organ damage and may be predictors of hypertensive nephrosclerosis.

AIM

We investigated changes in renal resistive index (RI) and urinary albumin excretion (UAE) in a group of patients with primary hypertension before and during long-term antihypertensive treatment.

METHODS

Thirty-two patients were randomized to receive antihypertensive treatment with either a calcium channel blocker (nifedipine GITS, up to 90 mg/day, n = 16) or an ACE inhibitor (lisinopril, up to 20 mg/day, n = 16), alone or in association with a diuretic (chlortalidone, 25 mg/day). Blood pressure, renal resistive index (by US Doppler) and UAE (mean of three nonconsecutive timed urinary collections, microg/min) were evaluated at baseline and over the course of 24 months of treatment.

RESULTS

Both regimens effectively lowered blood pressure (mean blood pressure from 123 +/- 1.8 at baseline to 103 +/- 1.5 mm Hg at 24 months in the lisinopril group and from 122 +/- 1.9 at baseline to 104 +/- 0.8 at 24 months in the nifedipine group, p < 0.001 for both groups). Overall, blood pressure decrease was associated with a reduction in UAE and no change in RI throughout the study. However, despite similar blood pressure reduction, the two regimens showed different specific effects. Lisinopril was associated with a significant decrease in both UAE (33.8 +/- 16.2 at baseline and 9.1 +/- 2.1 at 24 months, p < 0.01) and renal RI (0.61 +/- 0.02 at baseline and 0.56 +/- 0.04 at 24 months, p < 0.05) while nifedipine GITS did not significantly influence UAE (35.7 +/- 12.2 at baseline and 31.2 +/- 12.1 at 24 months, n.s.) or RI (0.61 +/- 0.01 at baseline and 0.59 +/- 0.02 at 24 months, n.s.).

CONCLUSION

Effective blood pressure control over a long period of time reduces the severity of organ damage, namely UAE while maintaining renovascular resistance in patients with essential hypertension. Different classes of antihypertensive agents might convey additional specific renal protection beyond blood pressure control. These data could be useful in devising individualized therapeutic strategies in hypertensive patients at increased renal risk.

Focal segmental glomerulosclerosis in African Americans

Focal segmental glomerulosclerosis (FSGS), the leading glomerular cause of the nephrotic syndrome among African Americans, is typically associated with edema, proteinuria, hypertension, microscopic hematuria, and renal insufficiency. Recent studies suggest that either the incidence of FSGS has increased or an increased number of biopsies of African American patients have made the diagnosis more common. The collapsing variant of FSGS, which occurs more commonly in African Americans than in whites, carries an especially poor prognosis with respect to renal survival. Although the pathogenesis of FSGS is not well understood, the fact that it frequently recurs early after transplantation has led to speculation that patients with FSGS may have a circulating factor that leads to increased glomerular permeability. There are no randomized control trials of treatment regimens for FSGS. Steroids, alkylating agents, and cyclosporin have all been used with variable results to treat FSGS.

The epidemiology of end-stage renal disease among African Americans

Although disparities in outcomes among African Americans compared with whites with respect to cardiovascular disease, cancer, diabetes, infant mortality, and other health standards have been well-described, these disparities are most dramatic with respect to kidney diseases. End-stage renal disease (ESRD) occurs almost 4 times more commonly in African Americans than in their white counterparts. These disparate rates of kidney disease may be caused by the complex interplay of genetic, environmental, cultural, and socioeconomic factors. African Americans are particularly vulnerable to the deleterious renal effects of hypertension and may require more aggressive blood pressure control than whites to accrue benefit with respect to preservation of renal function. Diabetes, the leading cause of ESRD in the United States, is another important factor in the excess renal morbidity and mortality of African Americans because of its prevalence in this population. Other renal diseases, especially those associated with HIV/AIDS, are also much more likely to affect African Americans than other American population subgroups. A more thorough understanding of the epidemiology of renal diseases in African Americans and the cultural, social, and biological differences that underlie racial disparities in prevalence of renal disease will be essential to the design of effective public health strategies for prevention and treatment of this burdensome problem.

Angiotensin-converting enzyme inhibitors and the risk of cancer: a population-based cohort study in Denmark

BACKGROUND

A recent observational study suggested that the use of angiotensin-converting enzyme (ACE) inhibitors protects against cancer in general and against breast and female reproductive tract cancers in particular. To explore these hypotheses, the authors examined cancer risk among users of ACE inhibitors in North Jutland County, Denmark.

METHODS

Using data from the population-based Prescription Database of North Jutland County and the Danish Cancer Registry, cancer incidence among 17,897 individuals prescribed ACE inhibitors was compared with expected incidence based on county specific cancer rates during an 8-year study period with a mean follow-up of 3.7 years. Standardized incidence ratios (SIRs) with corresponding 95% confidence intervals (95% CIs) were calculated for cancers overall and at selected sites. In addition, the authors performed a direct comparison of users of ACE inhibitors with users of beta-blockers or calcium channel blockers (n = 47,579 individuals) by means of a Cox proportional hazards model.

RESULTS

Overall, 909 cancer cases were observed among users of ACE inhibitors, with 846 expected based on general population rates, yielding an SIR of 1.07 (95% CI, 1.01-1.15). No risk reductions were observed for cancers of the breast and female reproductive tract, whereas nonsignificantly decreased SIRs were observed for cancers of the esophagus, stomach, and liver. Cancer of the kidney was found in significant excess (SIR, 1.6; 95% CI, 1.1-2.2). Stratification by duration of follow-up or number of prescriptions revealed no apparent trends, except for a tendency toward decreasing risk with increasing length of follow-up for smoking-related cancers. The direct comparison of users of ACE inhibitors with users of beta-blockers or calcium channel blockers yielded results comparable to those derived from the comparison with the general population, with a hazard ratio for cancer overall of 1.01 (95% CI, 0.93-1.09).

CONCLUSIONS

This large, population-based cohort study did not confirm a protective effect of ACE inhibitors on the development of cancer. The excess of kidney cancer observed likely reflects a correlation between hypertension and kidney cancer. Further investigation is needed to evaluate the long-term effects of ACE inhibitors beyond the observation period of this and previous studies. Also, the suggestive evidence of decreased risks for upper digestive system cancers and for smoking-related cancers over time may warrant additional investigation.

Long-term renal consequences of hypertension for normal and diseased kidneys

Substantial evidence indicates that the adverse effects of hypertension on the kidney depend on the degree to which systemic blood pressure elevations are transmitted to the renal microvasculature. Such blood pressure transmission and consequent susceptibility to hypertensive renal damage is markedly exacerbated in states characterized by preglomerular vasodilation and an impairment of the normally protective renal autoregulatory mechanisms, e.g. diabetes or chronic renal disease. Moreover, this pathophysiology gives rise to the prediction that prevention of hypertension-induced barotrauma will require blood pressure to be reduced well into the normotensive range in such patients, as is being recognized in the currently recommended blood pressure goals. Agents that block the renin-angiotensin system should be preferred as initial therapy as they may provide additional risk reductions and minimize the potassium and magnesium depletion associated with the diuretic use usually necessary to achieve the lower blood pressure targets. The current failure to achieve optimal blood pressure reductions may be contributing not only to the still escalating incidence of end-stage renal disease in diabetic patients, but also to their greatly increased cardiovascular morbidity and mortality.

Blood pressure reduction in the morning yields beneficial effects on progression of chronic renal insufficiency with regression of left ventricular hypertrophy

Self-monitoring values of blood pressure may better reflect the average long-term blood pressure value than sporadic measurements in the physician's office and be more useful for blood pressure control. In the present study, we compared the results of self-monitoring of blood pressure values, especially in the morning, with office blood pressure, and related these to progression of chronic renal insufficiency and left ventricular hypertrophy (LVH). Thirty-four patients were selected from 316 subjects with chronic renal insufficiency (average serum creatinine 1.72 +/- 0.15 mg/dl, mean age 52.6 +/- 3.5 yrs) in accordance with the following criteria (1) office blood pressure was less than 140/90 mmHg, (2) blood pressure was controlled with amlodipine (5-20 mg/day) combined with benazepril (2.5 mg/day), (3) morning blood pressure was greater than 150/90 mmHg at 6-9 AM and (4) LVH had been determined by echocardiography (posterior wall thickness; PWT > or = 12 mm). The patients were assigned to 2 groups at random and were given: (1) guanabenz (GB; 2-8 mg at I I PM, n = 17) or (2) placebo (n = 17). Two years later, the average blood pressure of both groups as measured in the office was not significantly different: however, BP in the morning was significantly reduced from 158 +/- 6 to 134 +/- 4 mmHg in GB treated group (P< 0.001). In 14 of 17 patients in GB treated group, LVH resolved and there was only mild progression of nephropathy (serum creatinine: 1.69 +/- 0.18 to 1.81 +/- 0.19 mg/dl). In 12 of 14 patients in placebo group, whose morning blood pressure remained at greater than 150/90 mmHg, LVH was retained and there was moderate progression of nephropathy (serum creatinine: 1.73 +/- 0.14 to 2.62 +/- 0.50mg/dl). From these results, it is suggested that antihypertensive treatment with combination therapy based on self-monitoring BP is cardio-renoprotective in patients with chronic renal insufficiency and LVH.

Antihypertensive treatment with and without benazepril in patients with chronic renal insufficiency: a US economic evaluation

OBJECTIVE

To conduct an economic analysis in the US of antihypertensive treatment with and without benazepril in patients with chronic renal insufficiency.

DESIGN

A four-state Markov model, using clinical data obtained from a 3-year randomised clinical trial [the Angiotensin-Converting-Enzyme Inhibition in Progressive Renal Insufficiency (AIPRI) study] plus its extension study (median 3.6 years), and cost data obtained from published US sources. The period of analysis was 7 years following randomisation.

PERSPECTIVE

Healthcare payer.

SETTING

Clinical data were obtained from multiple medical centres in three European countries as described in the published studies. Key economic data were obtained from the US Healthcare Financing Administration's End Stage Renal Disease programme.

PATIENTS AND INTERVENTIONS

In the clinical studies on which this economic analysis was based, patients with chronic renal insufficiency of various aetiologies were randomised to antihypertensive therapy with or without concomitant benazepril.

MAIN OUTCOME MEASURES AND RESULTS

Over 7 years of analysis, patients randomised to antihypertensive treatment with concomitant benazepril therapy incurred on average USD12991 (1999 values) lower medical costs than patients prescribed antihypertensive treatment without benazepril, and obtained an additional 0.091 quality-adjusted life years (QALYs). Costs and QALYs were greater for the benazepril arm than the placebo arm for all years of analysis after the first. Rank order stability of results favouring the benazepril therapy arm was found in sensitivity analyses of changes in key model parameters. Additional economic and health benefits favouring patients receiving benazepril would be seen if underlying model rates of dialysis and transplantation were increased, as may be appropriate to reflect treatment practice differences in the US relative to European countries.

CONCLUSIONS

Benazepril therapy as a component of antihypertensive treatment of persons with chronic renal insufficiency initially costs money, but investment costs are recouped quickly and return on investment continues to grow. The impact of end-stage renal disease on patient health and healthcare costs is great. Thus, the quality-adjusted survival benefits and overall cost savings seen in benazepril recipients over a prolonged period (2 to 7 years) indicate that the strategy of prescribing benazepril to reduce progression of renal disease in patients with renal insufficiency is both clinically and economically beneficial compared with current antihypertensive regimens without ACE inhibition.

Effect of combining an ACE inhibitor and an angiotensin II receptor blocker on plasma and kidney tissue angiotensin II levels

Increased angiotensin II (AII) activity has been recognized as a risk factor for progression of kidney disease. There is increasing clinical evidence that combining an angiotensin-converting enzyme (ACE) inhibitor with an AII receptor blocker (ARB) reduces proteinuria and blood pressure in patients with renal disease, although the mechanism of this synergistic effect remains poorly defined. This study tested whether the combination of an ACE inhibitor and an ARB reduces plasma AII (AIIp) and kidney tissue AII (AIIk) beyond what is observed with either of these two agents alone. Mean arterial pressure, glomerular filtration rate, AIIp, and AIIk were measured in four groups of Wistar rats after 2 weeks of a low-salt diet and 1 week of treatment with captopril (2.4 mg/d), losartan (1.7 mg/d), combination captopril+losartan (1.7 mg/d of captopril, 0.7 mg/d of losartan), or no treatment (control). Administration of captopril, losartan, and captopril+losartan produced statistically significant reductions in mean arterial pressure (control, 130 +/- 4 mm Hg; captopril, 92 +/- 5 mm Hg; losartan, 88 +/- 4 mm Hg; captopril+losartan, 104 +/- 5 mm Hg) and mild reductions in glomerular filtration rate (control, 3.1 +/- 0.1 mL/min; captopril, 2.2 +/- 0.3 mL/min; losartan, 1.7 +/- 0.3 mL/min; captopril+losartan, 2.3 +/- 0.3 mL/min) when compared with control rats, but no significant differences were observed among the treated groups. Captopril and captopril +losartan reduced AIIp significantly when compared with control (captopril, 43 +/- 8 pg/mL; captopril+losartan, 47 +/- 5 pg/mL; control, 134 pg/mL) and with losartan (99 +/- 2 pg/mL). AIIk values were reduced in captopril (254 +/- 18 pg/g kidney weight) and losartan (292 +/- 33 pg/g kidney weight) when compared with control (1,235 +/- 79 pg/g kidney weight). Captopril+losartan (136 +/- 17 pg/g kidney weight) reduced AIIk to values significantly lower than captopril or losartan alone. Higher doses of captopril (5 mg/d and 7.5 mg/d) or losartan (4 mg/d and 6 mg/d) alone did not reduce AIIk to the levels observed with combination low doses of captopril+losartan. Combining low doses of ACE inhibitor plus ARB reduces AIIk more than higher doses of either agent alone. This reduction in AIIk with ACE inhibitor plus ARB provides a mechanism to understand the synergism of this combination in reducing proteinuria and blood pressure. The reduction in AIIk with ACE inhibitor plus ARB may have important implications in long-term organ protection in hypertension and renal disease.

Cardiovascular risk in patients with early renal insufficiency: implications for the use of ACE inhibitors

Patients with end-stage renal disease die from cardiovascular disease at a much younger age than people in the general population do. Here, we review the evidence linking early renal insufficiency (ERI) to an increased cardiovascular risk. A number of cardiovascular risk factors become prevalent with ERI, including night-time hypertension, increase in serum levels of lipoprotein (a), homocysteine and asymmetric dimethyl-arginine, and insulin resistance. Also, an epidemiologic association between coronary artery disease (CAD) and nephrosclerosis, a frequent cause of ERI in the elderly, is documented. In the middle-aged, general population ERI, found in 8% of women and 9% of men, was not associated with cardiovascular disease. However, in a representative sample of middle-aged British men the risk of stroke was 60% higher for the subgroup of individuals with ERI. In people at high cardiovascular risk (mostly CAD), the Heart Outcomes Prevention Evaluation (HOPE) study found a 2-fold (unadjusted) or 1.4-fold (adjusted) higher incidence of cardiovascular outcomes with ERI. The incidence of primary outcome increased with the level of serum creatinine. At least four studies have determined the cardiovascular risk associated with ERI in hypertension. In Hypertension Detection and Follow-up Program, as in HOPE, cardiovascular mortality increased with higher serum creatinine levels (5-fold difference in cardiovascular mortality between the lowest and the highest creatinine strata). In patients with hypertension with low risk, the Hypertension Optimal Treatment and a small Italian trial found about a doubling in cardiovascular outcomes in ERI. However, in the Multiple Risk Factor Intervention Trial, not baseline serum creatinine level, but its increase on follow-up predicted future cardiovascular disease. These observational data suggest that ERI, independent of etiology, is a strong predictor of cardiovascular disease, present in 10% of a population at low, and up to 30% at high, cardiovascular risk. No prospective therapeutic trials aimed at reducing the cardiovascular burden in individuals with ERI are available. Subgroup analyses of the HOPE study indicate that ACE inhibition with ramipril is beneficial without an increased risk of adverse effects like acute renal failure or hyperkalemia. Thus the frequent practice of withholding ACE inhibitors from patients with mild renal insufficiency is unwarranted, especially since this identifies a group at high risk who appears to benefit most from treatment. In addition, there is evidence that ACE inhibitors improve renal outcomes in renal insufficiency. Prospective studies should test the predictive power of ERI for cardiovascular disease and therapeutic options.

Intensive blood pressure reduction is beneficial in patients with impaired cardiac function coexisting with chronic renal insufficiency

Both in CHF (congestive heart failure) and CRI (chronic renal insufficiency), blood pressure reduction is beneficial for preservation of cardiac and renal function. However, it is uncertain how much blood pressure reduction is appropriate in patients with both CHF and coexisting CRI. In the present study, we examined whether intensive blood pressure reduction is more beneficial in these patients than the usually accepted level of reduction. Thirty-five men and 21 women of average age 63+/-5 years suffering from both CHF and CRI were selected from 316 patients attending the Kidney Disease Center of Saitama Medical School Hospital. All participants had an ejection fraction (EF) of less than 55% as determined by echocardiography. Renal function was evaluated by 24-h creatinine clearance (GFR), and a GFR of less than 50 ml/min was regarded as indicating renal insufficiency. Patients were divided into 2 groups according to the target blood pressure: in group I, blood pressure (BP) was lowered to less than 120/75 mmHg and in group II, blood pressure was lowered to less than 130/80 but more than 121/76 mmHg. The daily doses of basic antihypertensive agents were amlodipine 5 to 20 mg, benazepril 2.5 to 5 mg, guanabenz 2 to 8 mg and furosemide 20 to 60 mg. At the end of a 2-year follow-up period, the BP in group I was controlled at the level of 118+/-4/73+/-3 mmHg with good maintenance of EF (46+/-4 to 60+/-4%) and GFR (44+/-4 to 40+/-3 ml/min). In group II, BP was maintained at 128+/-4/81+/-2 mmHg, accompanied by a reduction of EF (46+/-4 to 42+/-3%) and a significant reduction of GFR (44+/-3 to 35+/-3 ml/min). These results suggest that intensive blood pressure reduction might be beneficial in cases complicated by cardiorenal failure.

Renal outcome 25 years after donor nephrectomy

PURPOSE

The extended outcome after kidney donation has been a particular concern ever since the recognition of hyperfiltration injury. Few published reports have examined donor renal outcome after 20 years or greater. Kidney transplantation has been performed at the Cleveland Clinic Foundation since 1963, at which there is extensive experience with live donor transplantation. We assess the impact of donor nephrectomy on renal function, urinary protein excretion and development of hypertension postoperatively to examine whether renal deterioration occurs with followup after 20 years or greater.

MATERIALS AND METHODS

From 1963 to 1975, 180 live donor nephrectomies were performed at the Cleveland Clinic. We attempted to contact all patients to request participation in our study. Those 70 patients who agreed to participate in the study were mailed a package containing a 24-hour urine container (for assessment of creatinine, and total protein and albumin), a vial for blood collection (for assessment of serum creatinine) and a medical questionnaire. All specimens were returned to and processed by the Cleveland Clinic medical laboratories. Blood pressure was taken and recorded by a local physician. A 24-hour creatinine clearance and the Cockcroft-Gault formula were used to estimate renal function, and values were compared with an age adjusted glomerular filtration rate for a solitary kidney.

RESULTS

Mean patient followup was 25 years. The 24-hour urinary creatinine clearance decreased to 72% of the value before donation. For the entire study cohort serum creatinine and systolic blood pressure after donation were significantly increased compared with values before, although still in the normal range. The overall incidence of hypertension was comparable to that expected in the age matched general population. There was no gender or age difference (younger or older than 50 years) for 24-hour urinary creatinine clearance, or change in serum creatinine before or after donation. Urinary protein and albumin excretion after donation was significantly higher in males compared with females. There were 13 (19%) subjects who had a 24-hour urinary protein excretion that was greater than 0.15 gm./24 hours, 5 (7%) of whom had greater than 0.8. No gender difference was noted in blood pressure, and there were no significant changes in diastolic pressure based on gender or age.

CONCLUSIONS

Overall, renal function is well preserved with a mean followup of 25 years after donor nephrectomy. Males had significantly higher protein and albumin excretion than females but no other clinically significant differences in renal function, blood pressure or proteinuria were noted between them or at age of donation. Proteinuria increases with marginal significance but appears to be of no clinical consequence in most patients. Patients with mild or borderline proteinuria before donation may represent a subgroup at particular risk for the development of significant proteinuria 20 years or greater after donation. The overall incidence of proteinuria in our study is in the range of previously reported values after donor nephrectomy.

Renal outcome 25 years after donor nephrectomy

PURPOSE

The extended outcome after kidney donation has been a particular concern ever since the recognition of hyperfiltration injury. Few published reports have examined donor renal outcome after 20 years or greater. Kidney transplantation has been performed at the Cleveland Clinic Foundation since 1963, at which there is extensive experience with live donor transplantation. We assess the impact of donor nephrectomy on renal function, urinary protein excretion and development of hypertension postoperatively to examine whether renal deterioration occurs with followup after 20 years or greater.

MATERIALS AND METHODS

From 1963 to 1975, 180 live donor nephrectomies were performed at the Cleveland Clinic. We attempted to contact all patients to request participation in our study. Those 70 patients who agreed to participate in the study were mailed a package containing a 24-hour urine container (for assessment of creatinine, and total protein and albumin), a vial for blood collection (for assessment of serum creatinine) and a medical questionnaire. All specimens were returned to and processed by the Cleveland Clinic medical laboratories. Blood pressure was taken and recorded by a local physician. A 24-hour creatinine clearance and the Cockcroft-Gault formula were used to estimate renal function, and values were compared with an age adjusted glomerular filtration rate for a solitary kidney.

RESULTS

Mean patient followup was 25 years. The 24-hour urinary creatinine clearance decreased to 72% of the value before donation. For the entire study cohort serum creatinine and systolic blood pressure after donation were significantly increased compared with values before, although still in the normal range. The overall incidence of hypertension was comparable to that expected in the age matched general population. There was no gender or age difference (younger or older than 50 years) for 24-hour urinary creatinine clearance, or change in serum creatinine before or after donation. Urinary protein and albumin excretion after donation was significantly higher in males compared with females. There were 13 (19%) subjects who had a 24-hour urinary protein excretion that was greater than 0.15 gm./24 hours, 5 (7%) of whom had greater than 0.8. No gender difference was noted in blood pressure, and there were no significant changes in diastolic pressure based on gender or age.

CONCLUSIONS

Overall, renal function is well preserved with a mean followup of 25 years after donor nephrectomy. Males had significantly higher protein and albumin excretion than females but no other clinically significant differences in renal function, blood pressure or proteinuria were noted between them or at age of donation. Proteinuria increases with marginal significance but appears to be of no clinical consequence in most patients. Patients with mild or borderline proteinuria before donation may represent a subgroup at particular risk for the development of significant proteinuria 20 years or greater after donation. The overall incidence of proteinuria in our study is in the range of previously reported values after donor nephrectomy.

Sustained improvement of renal graft function for two years in hypertensive renal transplant recipients treated with nifedipine as compared to lisinopril

BACKGROUND

Treatment of posttransplant hypertension is still a matter of debate. Calcium antagonists may ameliorate renal side effects of cyclosporin. Angiotensin converting enzyme- (ACE) inhibitors may be more effective in sustaining renal function in native chronic renal disease. We prospectively compared the effect of controlled release nifedipine and lisinopril on long-term renal function in hypertensive kidney transplant patients treated with cyclosporin.

METHODS

A total of 154 renal transplant patients presenting with hypertension (diastolic blood pressure >or=95 mmHg) during the first 3 weeks after transplantation were randomised to receive double-blind nifedipine 30 mg or lisinopril 10 mg once daily. A total of 123 patients completed 1 year of treatment (69 nifedipine, 54 lisinopril) and 64 patients completed 2 years of double-blind treatment (39 nifedipine, 25 lisinopril). Baseline glomerular filtration rate was measured as 99 mTc-diethylene-triaminepentaacetate clearance in a stable phase 2 to 5 weeks after inclusion and repeated at 1 and 2 years.

RESULTS

Baseline glomerular filtration rates were similar (46+/-16 ml/min with nifedipine, 43+/-14 ml/min with lisinopril). The changes in glomerular filtration rates from baseline were statistically significant between the groups after 1 year (9.6 ml/min mean treatment difference (95% confidence interval [CI]s 5.5-13.7 ml/min, P=0.0001) and remained statistically significant also after 2 years (10.3 ml/min mean difference (95% CIs 4.0-16.6], P=0.0017). After 1 year glomerular filtration rates averaged 56+/-19 ml/min in the nifedipine group and 44+/-14 ml/min in the lisinopril group.

CONCLUSIONS

Both nifedipine and lisinopril were safe and effective in treatment of hypertension in renal transplant patients treated with cyclosporin. Patients receiving nifedipine but not lisinopril improved kidney transplant function over a period of 2 years.

Metabolic pathogenesis of cardiorenal disease

Clinical data have established microalbuminuria/proteinuria as an independent risk factor for the development and progression of renal disease in patients with either diabetes or essential hypertension. Decreased kidney function is associated with increased cardiovascular risk, even at modest reductions in estimated creatinine clearance (to approximately 60 mL/min/1.73 m(2)) or modest elevations in serum creatinine (>1.4 mg/dL). Treatment with angiotensin-converting enzyme inhibitors has been shown in clinical trials to delay or stabilize the rate of progression of renal disease. Reduction in cardiovascular events, such as stroke and myocardial infarction, also has been shown in these high-risk individuals. These effects are dependent and independent of blood pressure control, suggesting a nonhemodynamic effect in blockade of the renin-angiotensin system. In conjunction with other therapeutic interventions, such as dietary modification and control of serum lipids, it appears that for at least a subgroup of patients it is possible to delay or prevent progression of kidney failure. There frequently is a clustering of risk factors in these individuals, including insulin resistance, salt sensitivity, hypertension, and dyslipidemia. The mechanism of the relationship between albuminuria and cardiovascular disease is unclear but may be related to endothelial cell dysfunction. Nonetheless, the presence of microalbuminuria/proteinuria as a marker for cardiovascular disease has important implications for the identification and treatment of individuals at risk.

High serum enalaprilat in chronic renal failure

BACKGROUND

Most angiotensin-converting enzyme (ACE) inhibitors and their metabolites are excreted renally and doses should hence be reduced in renal insufficiency. We studied whether the dosage of enalapril in daily clinical practice is associated with drug accumulation of enalaprilat in chronic renal failure.

METHODS

Fifty nine out-patients with plasma creatinine >150 micromol/L and chronic antihypertensive treatment with enalapril were investigated, in a cross-sectional design.

RESULTS

Median glomerular filtration rate (GFR) was 23(range 6-60) ml/minute/1.73 m2. The daily dose of enalapril was 10 (2.5-20) mg and the trough serum concentration of enalaprilat was 31.8 (<2.5-584.7)ng/ml. Ninety percent of the patients had higher serum concentrations of enalaprilat than has been reported in subjects with normal kidney function, and a marked elevation of serum enalaprilat was observed in patients with GFR <30 ml/minute. All but three patients had serum ACE activity below the reference range. The ACE genotype did not influence the results. Additional pharmacokinetic studies were done in nine patients in whom GFR was 23 (10-42)ml/minute/1.73 m2. The median clearance of enalaprilat was 28 (16-68) ml/minute and correlated linearly with GFR (r=0.86, p=0.003). Intra-subject day-to-day variation in trough concentrations was 19.7%.

CONCLUSION

Patients with chronic renal failure given small or moderately high doses of enalapril may thus have markedly elevated levels of serum enalaprilat. Whether this affords extra renoprotection, or on the contrary may inappropriately impair renal function, is not known, and should be investigated in prospective, controlled studies.

Optimal antiproteinuric dose of losartan in nondiabetic patients with nephrotic range proteinuria

Although the antiproteinuric response to antihypertensive treatment is the main predictor of renoprotective efficacy in long-term renal disease, to date, dose-finding studies of antihypertensives have been based only on blood pressure. We aimed to find the optimal antiproteinuric dose of the angiotensin II antagonist losartan. An open-label, dose-response study using subsequent 6-week treatment periods was performed in 10 nondiabetic patients with proteinuria of 5.8 +/- 0.8 g/d and a mean arterial pressure of 103 +/- 3.7 mm Hg without antihypertensive medication. All patients had normal to moderately impaired renal function. After the baseline period, five periods followed with a daily losartan dose of 50 mg, 100 mg, 150 mg, and 50 mg and a recovery without losartan. At the end of each period, proteinuria and mean arterial pressure were measured. The consecutive doses of losartan had a similar antihypertensive response (-11.3 +/- 2.8% by the 100-mg dose). The optimal antiproteinuric response was reached at 100 mg of losartan (-30 +/- 8%). The 50-mg dose (-13 +/- 7%) was less effective, and the 150-mg dose (-28 +/- 8%) was not more effective. A 100-mg dose of losartan is optimal for reduction of proteinuria in nondiabetic patients with nephrotic range proteinuria.

Renal function: the Cinderella of cardiovascular risk profile

The presence of an altered renal function in essential hypertension, advanced heart failure (HF) and after a myocardial infarction (MI) is associated with higher cardiovascular morbidity and mortality. Indices of altered renal function (e.g., microalbuminuria, increased serum creatinine concentrations, decrease in estimated creatinine clearance or overt proteinuria) are independent predictors of cardiovascular morbidity and mortality in any of the three clinical situations. These parameters should then be routinely evaluated in clinical practice. These facts have several therapeutic implications. First, although there is no evidence-based information on the level of blood pressure that confers optimal renal protection, levels substantially lower than past recommendations are advisable. Second, hypertensive kidney damage should be prevented by early treatment of hypertensive patients, particularly those with microalbuminuria. Finally, to avoid further aggravation of high cardiovascular risk, antihypertensive agents devoid of unwanted metabolic side effects should be used for the treatment of hypertensive vascular damage. In HF, the combination of an angiotensin-converting enzyme (ACE) inhibitor and a beta-blocker seem to be the most renoprotective. Renal outcome is also improved by ACE inhibition after an MI. Finally, renal and cardiovascular outcome seem to run in parallel in all these situations.

Achieving maximal renal protection in nondiabetic chronic renal disease

A rapid global increase in the number of patients requiring renal replacement therapy necessitates that effective strategies for renal protection are developed and applied widely. We review the experimental and clinical evidence in support of individual renoprotective interventions, including angiotensin-converting enzyme therapy, control of systemic hypertension, dietary protein restriction, reduction of proteinuria, treatment of hyperlipidemia, and smoking cessation. We also consider potential future renoprotective therapies. To achieve maximal renal protection, a comprehensive strategy employing all of these elements is required. This strategy should be directed at normalizing clinical markers of renal disease to induce a state of remission.

The relevance of tissue angiotensin-converting enzyme: manifestations in mechanistic and endpoint data

Angiotensin-converting enzyme (ACE) is primarily localized (>90%) in various tissues and organs, most notably on the endothelium but also within parenchyma and inflammatory cells. Tissue ACE is now recognized as a key factor in cardiovascular and renal diseases. Endothelial dysfunction, in response to a number of risk factors or injury such as hypertension, diabetes mellitus, hypercholesteremia, and cigarette smoking, disrupts the balance of vasodilation and vasoconstriction, vascular smooth muscle cell growth, the inflammatory and oxidative state of the vessel wall, and is associated with activation of tissue ACE. Pathologic activation of local ACE can have deleterious effects on the heart, vasculature, and the kidneys. The imbalance resulting from increased local formation of angiotensin II and increased bradykinin degradation favors cardiovascular disease. Indeed, ACE inhibitors effectively reduce high blood pressure and exert cardio- and renoprotective actions. Recent evidence suggests that a principal target of ACE inhibitor action is at the tissue sites. Pharmacokinetic properties of various ACE inhibitors indicate that there are differences in their binding characteristics for tissue ACE. Clinical studies comparing the effects of antihypertensives (especially ACE inhibitors) on endothelial function suggest differences. More comparative experimental and clinical studies should address the significance of these drug differences and their impact on clinical events.

Beyond the usual strategies for blood pressure reduction: therapeutic considerations and combination therapies

Rapidly accumulating clinical data have repeatedly demonstrated not only the critical importance of even small increases in blood pressure as a pathophysiologic factor in the development of cardiovascular disease, particularly in individuals with diabetes mellitus, but also the therapeutic necessity of more aggressive blood pressure reduction and the achievement of progressively lower blood pressure targets in reducing cardiovascular event rates. JNC VI has defined optimal blood pressure as <or=120/80 mm Hg, and Stage 1 hypertension as >or=140/80 mm Hg. Target blood pressures are now <or=130/80 mm Hg in patients with diabetes and <125/75 mm Hg for patients with hypertensive renal disease with proteinuria of >1 gm/24 hours. Achieving such target pressures is increasingly difficult, particularly in diabetic patients with chronic renal disease, who require complex multidrug antihypertensive regimens. This review attempts to provide some suggestions for constructing such antihypertensive regimens, and provides considerations for the appropriate use of diuretics and the most effective drug combinations. Factors potentially contributing to drug resistant hypertension include such problems as failure to maximize drug dosing, suboptimal diuretic use, noncompliance, and possible confounding effects of such concomitant medications as nonsteroidal and anti-inflammatory drugs or decongestants. The issues underlying drug-resistant hypertension are listed, together with strategies for overcoming this problem.

Angiotensin-converting enzyme inhibitors and the risk of cancer: a population-based cohort study in Denmark

BACKGROUND

A recent observational study suggested that the use of angiotensin-converting enzyme (ACE) inhibitors protects against cancer in general and against breast and female reproductive tract cancers in particular. To explore these hypotheses, the authors examined cancer risk among users of ACE inhibitors in North Jutland County, Denmark.

METHODS

Using data from the population-based Prescription Database of North Jutland County and the Danish Cancer Registry, cancer incidence among 17,897 individuals prescribed ACE inhibitors was compared with expected incidence based on county specific cancer rates during an 8-year study period with a mean follow-up of 3.7 years. Standardized incidence ratios (SIRs) with corresponding 95% confidence intervals (95% CIs) were calculated for cancers overall and at selected sites. In addition, the authors performed a direct comparison of users of ACE inhibitors with users of beta-blockers or calcium channel blockers (n = 47,579 individuals) by means of a Cox proportional hazards model.

RESULTS

Overall, 909 cancer cases were observed among users of ACE inhibitors, with 846 expected based on general population rates, yielding an SIR of 1.07 (95% CI, 1.01-1.15). No risk reductions were observed for cancers of the breast and female reproductive tract, whereas nonsignificantly decreased SIRs were observed for cancers of the esophagus, stomach, and liver. Cancer of the kidney was found in significant excess (SIR, 1.6; 95% CI, 1.1-2.2). Stratification by duration of follow-up or number of prescriptions revealed no apparent trends, except for a tendency toward decreasing risk with increasing length of follow-up for smoking-related cancers. The direct comparison of users of ACE inhibitors with users of beta-blockers or calcium channel blockers yielded results comparable to those derived from the comparison with the general population, with a hazard ratio for cancer overall of 1.01 (95% CI, 0.93-1.09).

CONCLUSIONS

This large, population-based cohort study did not confirm a protective effect of ACE inhibitors on the development of cancer. The excess of kidney cancer observed likely reflects a correlation between hypertension and kidney cancer. Further investigation is needed to evaluate the long-term effects of ACE inhibitors beyond the observation period of this and previous studies. Also, the suggestive evidence of decreased risks for upper digestive system cancers and for smoking-related cancers over time may warrant additional investigation.

Optimizing medical management of patients with pre-end-stage renal disease

Patients with end-stage renal disease have reduced quality of life, high levels of morbidity, and an annual mortality of about 22%. Because the high morbidity and mortality of dialysis patients might be reduced substantially if patients were healthier at the time of initiating renal replacement therapy, this article will present treatment recommendations designed to retard the progression of chronic renal disease, to optimize the medical management of comorbid medical conditions, such as cardiovascular disease, diabetes, and lipid disorders, and to reduce the complications of renal insufficiency, including hypertension, anemia, hyperparathyroidism, and malnutrition. Given the lack of prospective clinical studies in this area, these recommendations are derived from consensus standards for managing dialysis patients or patients with cardiovascular disease, hypertension, diabetes, and lipid disorders, and from expert opinion derived from laboratory investigations of pathophysiology and relevant experimental disease models.

Pathogenesis of diabetic nephropathy: focus on transforming growth factor-beta and connective tissue growth factor

Although considerable improvement in the prognosis of diabetic nephropathy has been achieved in recent years due to intensive insulin and angiotensin-converting enzyme inhibitor treatment, these approaches do not provide complete protection against progression of diabetic nephropathy. An urgent need for additional novel therapies to prevent or further slow the progression of diabetic nephropathy motivated us to provide an up-to-date review with particular emphasis on the potential role of two growth factors--transforming growth factor-beta and connective tissue growth factor--in the pathogenesis of diabetic nephropathy. The most intensively studied to date, transforming growth factor-beta appears to play a central role in the pathogenesis of diabetic nephropathy. Recently, attention has focused on connective tissue growth factor, which mimics the biological activity of transforming growth factor-beta in profibrotic tissue formation. Thus, acting as a downstream mediator of the profibrotic activity of transforming growth factor-beta, connective tissue growth factor may constitute a more specific target for future antifibrotic therapies.

Modulation of incipient glomerular lesions in experimental diabetic nephropathy by hypotensive and subhypotensive dosages of an ACE inhibitor

A glomerular permeability defect occurs early in the course of type 1 diabetes and precedes the onset of microalbuminuria and renal morphological changes. Recently, ACE inhibitors have been shown to prevent loss of glomerular membrane permselective function, but the mechanism of this nephroprotective effect is still being debated. The objective of the present study was to evaluate the effects of hypotensive and subhypotensive dosages of the ACE inhibitor quinapril ex vivo and of its active metabolite quinaprilat in vitro on the glomerular albumin permeability (P(alb)) defect in the early phases of experimental diabetes. For the ex vivo study, six groups of male Wistar rats were evaluated for 4 weeks. One group served as a nondiabetic control (C); the other five groups were rendered diabetic and included untreated diabetic rats (D) and diabetic rats receiving quinapril at the dosages of 5 (DQ1), 2.5 (DQ2), 1.25 (DQ3), and 0.625 (DQ4) mg. kg(-1). day(-1). Dosage-dependent effects of quinapril on systolic blood pressure and the glomerular filtration rate were observed. In contrast, control of P(alb) in isolated glomeruli exposed to oncotic gradients, proteinuria, and glomerular and tubular hypertrophy was obtained with subhypotensive dosages (DQ3 and DQ4 groups) of the ACE inhibitor. In the in vitro study, quinaprilat reduced P(alb) significantly in concentration ranges from 10(-6) to 10(-14) mol/l compared with results in control glomeruli. The effect on P(alb) may have occurred by mechanisms different from kidney ACE inhibitor. These study results indicated that ACE inhibitor treatment prevents the early onset of the P(alb) defect in experimental diabetes. This effect seemed to occur independently of systemic or glomerular hemodynamic changes and, at least partially, from kidney ACE inhibition.