Antihypertensive therapy and progression of diabetic renal disease

ACE Inhibition in Anti-Thy1 Glomerulonephritis Limits Proteinuria but Does Not Improve Renal Function and Structural Remodeling

Background/Aims

ACE inhibitor (ACE-I) treatment effectively inhibits proteinuria and ameliorates the course of various renal diseases. In experimental glomerulonephritis, however, angiotensin II (AngII) infusion has also been shown to be renoprotective. We evaluated the long-term (28 days) course of anti-Thy1 glomerulonephritis in animals with suppressed AngII formation by ACE-I treatment.

Methods

Brown Norway rats received perindopril (2.8 mg/kg/day, n = 12), dihydropyridine calcium-antagonist amlodipine (Ca-A; 13 mg/kg/day, n = 6) or were left untreated (n = 14). All animals were monitored for blood pressure, proteinuria, and creatinine clearance after anti-Thy1 injection. Renal histology was assessed at day 7 and 28.

Results

Systolic blood pressure was equally reduced by ACE-I and Ca-A treatment. AngII suppression prevented development of proteinuria, but did not protect against glomerular microaneurysm formation or reduction in creatinine clearance. After resolution of the microaneurysms, animals with suppressed AngII production showed a modest increase in glomerulosclerosis and vasculopathic thickening of intrarenal vessels.

Conclusions

In anti-Thy1 glomerulonephritis, suppression of AngII formation does not protect against the induction of glomerular damage and is associated with mild aggravation of adverse renal fibrotic remodeling. Proteinuria, however, is effectively prevented by ACE-I treatment. Ca-A treatment did not affect the course of glomerulonephritis, indicating that ACE-I effects are blood pressure independent.

Verapamil Reverts Acute Renal Functional Impairment Induced by Angiotensin II Converting Enzyme Inhibitors

Angiotensin converting enzyme inhibitors (ACEI) reduce blood pressure (BP) and provide end-organ protection, but may induce renal function deterioration. In these cases, serum creatinine (SCr) can be normalized by ACEI withdrawn. In some patients, it could be desirable to maintain the ACEI for the protection of the kidney and heart. The objective of the study was to evaluate the effect of Verapamil (V) on renal function added to patients with elevated SCr due to ACEI treatment. In 46 hypertensive patients without previous renal failure, in which ACEI treatment induced an acute increase in SCr (> or = 20% or 0.5 mg/dL), ACEI treatment was maintained and 180 mg/day of V was added for 12 weeks. Those patients showing further SCr increase or no BP control at four weeks were withdrawn. Patients under BP control were moved on the combination V 180 + Trandolapril 2 mg/day for eight weeks more. SCr decreased from 136 +/- 49 micromol/L at baseline to 126 +/- 49 at 12 weeks after adding V (p < 0.001) and to 111 +/- 31 micromol/L at 20 weeks (p < 0.01). Creatinine clearance increased from 62 +/- 22 mL/min at baseline to 68 +/- 28 after 12 weeks of V (p < 0.001). This article demonstrates than in patients with acute renal function impairment secondary to ACEI treatment, the addition of 180 mg/day of verapamil to ACEI reverses SCr towards previous values.

Inhibition of IGF-I-induced Erk 1 and 2 activation and mitogenesis in mesangial cells by bradykinin

BACKGROUND

The beneficial effects of therapeutic angiotensin-converting enzyme (ACE) inhibitor treatment against the worsening of glomerulosclerosis during the course of diabetic nephropathy have been widely documented. ACE inhibitors inhibit both angiotensin II formation and bradykinin (BK) degradation, thereby reducing angiotensin II type 1 (AT1) receptor activity and favoring B2-kinin receptor (B2 receptor) activation. Since the involvement of growth factors such as insulin-like growth factor (IGF-I) has been implicated in the early steps of diabetic nephropathy, we investigated the effect of BK on Erk 1 and 2 activation and cell proliferation by IGF-I.

METHODS

The activation of Erk 1 and 2 in mesangial cells (MCs) and isolated glomeruli (IG) was investigated by immunoprecipitation and Western blotting during activation of the IGF-I receptor in the presence or absence of BK and of protein kinase C (PKC), tyrosine-kinase and phosphatase selective inhibitors. Mesangial cell proliferation was assessed in vitro by cell counting.

RESULTS

In untreated MCs and IG, when added separately, BK and IGF-I both activated Erk 1 and 2. In contrast, in MCs and IG pretreated with BK, the IGF-I-induced Erk 1 and 2 activation was dose-dependently reduced. The inhibitory effect of BK on IGF-I-induced activation of Erk 1 and 2 was completely abolished by addition of a B2 antagonist, by chelation of intracellular calcium and by tyrosine phosphatase inhibition. Additionally, BK reduced MC proliferation induced by IGF-I.

CONCLUSIONS

A new inhibitory pathway of the early steps of IGF-I signaling by the B2 receptor is found both in cultured MCs and in IG, which involves a calcium-dependent tyrosine phosphatase activity. Recruitment of this mechanism may account for the beneficial effects of ACE inhibitor treatment on glomerulosclerosis associated with diabetic nephropathies.

Prescribing patterns and therapeutic implications for diabetic hypertension in Bahrain

OBJECTIVE

To determine drug prescription patterns and the extent of conformity with World Health Organization/international Society of Hypertension (WHO/ISH) guidelines in diabetic hypertension.

DESIGN

Retrospective prescription-based survey.

SETTING

Seven primary-care health centers, comprising approximately one-third of primary-care health centers in Bahrain.

PATIENTS

Patients with type 2 diabetes and hypertension.

MAIN OUTCOME MEASURE

The prescribing pattern of antihypertensive and antidiabetic drugs.

RESULTS

Among a study sample of 1,463 patients with type 2 diabetes and hypertension, antidiabetic agents were prescribed as monotherapy in the following descending order: glyburide, gliclazide, insulin, and metformin. As combinations, sulfonylureas plus metformin was most popular, followed by metformin plus insulin, and sulfonylureas plus insulin. Sulfonylurea and metformin with insulin was rarely used. There was no significant difference in prescribing of glyburide and metformin between the elderly and young middle-aged diabetic patients; many patients older than 65 years were treated with a beta-blocker along with a long-acting sulfonylurea. Both as monotherapy and in overall use, beta-blockers, angiotensin-converting enzyme (ACE) inhibitors, and calcium-channel blockers were most often prescribed. Among 35.5% patients treated with antihypertensive combinations, various two- and three-drug combinations of beta-blockers, ACE inhibitors, calcium-channel blockers, and diuretics were often used. The proportion of patients taking atenolol 100 mg/d was higher with combination regimens. Hydrochlorothiazide 25 mg or equivalent thiazide diuretics were extensively used.

CONCLUSIONS

The prescribing pattern of antihypertensives in diabetic hypertension differs in many instances from WHO/ISH guidelines, especially regarding the choice of antihypertensive drugs and their combinations. The appropriateness of antidiabetic drug choice is questionable in relation to the antihypertensive used.

Evaluation of Losartan Usage in a Regional Hospital in Hong Kong

Objective:

To determine whether losartan usage follows the hospital's guidelines in terms of indications and reasons for use and to assess the accuracy of physicians in completing the losartan usage monitoring forms.

Design:

Drug utilization survey.

Setting:

A major government hospital in Hong Kong.

Participants:

Inpatients or outpatients prescribed losartan for the first time.

Intervention:

Physicians were to complete a monitoring form with both indications and reasons for losartan use.

Main Outcome Measures:

The appropriateness of losartan prescribing was evaluated in terms of indications (for hypertension with impaired left-ventricular function or hypertension in diabetic patients with persistent proteinuria) and reasons for preferred use (previous intolerance to adverse effects of angiotensin-converting enzyme inhibitors). The accuracy of completed monitoring forms was also assessed.

Results:

Forty-eight patients were prescribed losartan since its addition to the hospital formulary through the end of the study period (September 1997-May 1998). A review of medical records (regardless of the information provided by the physicians on the monitoring forms) revealed that 39 patients (81.3%) were prescribed losartan for appropriate indications and that 22 (45.8%) were given losartan rather than angiotensin-converting enzyme inhibitors for appropriate reasons according to the guidelines. Both appropriate indications and reasons were met in only 15 patients (31.3%). Of the 48 monitoring forms that were collected, three (6.3%) were not completed. The concordance rate of information provided by the doctors and information from case notes was 61.5% for indications and 34.8% for reasons of preferred use.

Conclusions:

Adherence to the hospital's usage guidelines and accuracy of the monitoring forms were suboptimal. Considering the high cost of losartan and its potential for long-term use, more educational activities, better dissemination of information, and more frequent evaluation of the acceptability of recommended usage guidelines are warranted.

Drug treatment of hypertension complicating diabetes mellitus

Hypertension and diabetes mellitus are both common conditions associated with a high morbidity and mortality. When the two conditions occur together, as they do in 50% of diabetic individuals, the result is a 7.2-fold increase in mortality. If hypertension occurs in association with diabetes mellitus and diabetic nephropathy, mortality rises to 37-fold above that of a healthy population. Despite the increase in incidence of nephropathy, cardiovascular disease remains the major cause of death in diabetic individuals. Therapy should therefore take into consideration the results of large, placebo-controlled trials which have shown reduction in cardiovascular morbidity and mortality as a result of active treatment. Although studies with the newer antihypertensive agents such as calcium antagonists and angiotensin converting enzyme (ACE) inhibitors are ongoing, only diuretics and beta-adrenoceptor antagonists have been clearly shown to reduce cardiovascular risk. Despite concerns regarding adverse metabolic effects and loss of hypoglycaemic awareness, beta-blockers and diuretics do have a role in the management of diabetic patients. While it is clear that ACE inhibitors reduce the progression of diabetic nephropathy, evidence suggests that diuretics may be just as effective. However, unlike diuretics or beta-blockers, ACE inhibitors have no proven benefit in the prevention of stroke of myocardial infarction. Despite the claims of metabolic neutrality made for many antihypertensive agents there appears to be no advantage in their use in the majority of hypertensive diabetic patients, except where there exist specific contraindications to established therapies.

Renal effects of antihypertensive therapy in uninephrectomized diabetic rats

Diabetic nephropathy is a major cause of chronic renal failure. The evidence available indicates that renal hemodynamics are altered in clinical and experimental diabetes mellitus. In these circumstances, an increased glomerular filtration rate (GFR) is associated with albuminuria and eventually with glomerulosclerosis. We studied the renal and hemodynamic effects of long-term treatment (5 months) using an angiotensin-converting enzyme inhibitor (trandolapril, 0.7 mg/g b.w. per day) and a calcium antagonist (verapamil, 20 mg/g b.w. per day), and the combination of the two (veratran) at the same dose, on streptozotocin-diabetic uninephrectomized rats. A moderate degree of hyperglycemia (2-4 g/l) was maintained with daily insulin. Mean arterial pressure (MAP) was measured monthly using the tail-cuff method. Determinations were made of urinary protein excretion, creatinine clearance, urinary electrolyte excretion and, at the end of treatment, renal and cardiac hypertrophy. MAP was similar in control and untreated diabetic rats. Trandolapril and veratran reduced MAP whereas verapamil alone had no effect on these animals. All groups showed a slight proteinuria that increased with verapamil treatment. The GFR of diabetic animals was higher than in the control group (mainly the first 2 months), except for veratran group, in which it was similar to the control value. Urinary electrolyte excretion increased in all diabetic groups with no significant differences among them. Veratran induced a protective effect against cardiac hypertrophy. None of the treatments affected renal hypertrophy. It is concluded that in a murine model of diabetes without hypertension or proteinuria, a combination of verapamil and trandolapril prevents hyperfiltration whereas verapamil alone increases proteinuria.

Effects of benazepril and nicardipine on microalbuminuria in normotensive and hypertensive patients with diabetes

Diabetic nephropathy is the most frequent cause of chronic renal failure. The onset of microalbuminuria in patients with diabetes mellitus, which seems to be related to blood pressure and the control of glycemia, is predictive of the development of true proteinuria. This multicenter, single-blind, randomized study examined the effects of benazepril and nicardipine on overnight microalbuminuria in 57 normotensive and 46 hypertensive diabetic patients. At the end of a 3-month placebo run-in period, the patients were stratified on the basis of the presence or absence of arterial hypertension and, within each stratum, randomized to receive one daily tablet of 10 mg benazepril or one tablet of 20 mg nicardipine twice daily for 6 months. Renal hemodynamics was investigated in 25 patients. Both drugs decreased overnight microalbuminuria throughout the study period, but benazepril was more effective than nicardipine (p = 0.025); in the patients with hypertension, both drugs led to a similar marked reduction in systolic and diastolic blood pressure. This study shows that benazepril was more effective than nicardipine in reducing overnight microalbuminuria in patients with diabetes mellitus, independently of their antihypertensive properties.