Renoprotection of angiotensin receptor blockers: beyond blood pressure lowering

Angiotensin II receptor blocker partially ameliorated intrarenal hypoxia in chronic kidney disease patients: a pre-/post-study

Chronic intrarenal hypoxia has been regarded as a pathogenic factor of progressive renal damage. However, the lack of available human data has impeded the progress in this field. In this work, blood oxygen level-dependent magnetic resonance imaging was used to determine intrarenal oxygen status pre- and post-angiotensin receptor blockade (olmesartan) treatment in normal subjects, diabetic chronic kidney disease (CKD) patients and non-diabetic CKD patients. The mean R2*, which represents intrarenal oxygenation, was significantly lower in the control group than in the CKD group (12.42 ± 0.53 /s vs 18.89 ± 3.15 /s, P < 0.01), indicating the presence of intrarenal hypoxia in the CKD patients. The olmesartan treatment induced a 16.2 ± 7.7% decrement of the mean R2* in CKD patients, suggesting that this drug had an intrarenal hypoxia ameliorating effect.

Chelation: a fundamental mechanism of action of AGE inhibitors, AGE breakers, and other inhibitors of diabetes complications

This article outlines evidence that advanced glycation end product (AGE) inhibitors and breakers act primarily as chelators, inhibiting metal-catalyzed oxidation reactions that catalyze AGE formation. We then present evidence that chelation is the most likely mechanism by which ACE inhibitors, angiotensin receptor blockers, and aldose reductase inhibitors inhibit AGE formation in diabetes. Finally, we note several recent studies demonstrating therapeutic benefits of chelators for diabetic cardiovascular and renal disease. We conclude that chronic, low-dose chelation therapy deserves serious consideration as a clinical tool for prevention and treatment of diabetes complications.

Physician adherence to hypertension treatment guidelines and drug acquisition costs of antihypertensive drugs at the cardiac clinic: a pilot study

Prescribing pattern surveys are one of the pharmacoepidemiological techniques that provide an unbiased picture of prescribing habits. Prescription surveys permit the identification of suboptimal prescribing patterns for further evaluation. The aims of this study were to determine the prescribing trend, adherence of the prescribers to the guideline, and the impact of drug expenditure on drug utilization at the cardiac clinic of Penang Hospital, Malaysia. This was a cross-sectional study. Demographic data of the patients, diagnoses and the drugs prescribed were recorded. The average drug acquisition costs (ADAC) were calculated for each antihypertensive drug class on a daily and annual basis. Adherence to the guideline was calculated as a percentage of the total number of patients. A total of 313 individuals fulfilled the inclusion criteria. The average age of the study population was 59.30 ± 10.35 years. The mean number of drugs per prescription in the study was 2.09 ± 0.78. There were no significant differences in the demographic data. Antihypertensive drugs were used in monotherapy and polytherapy in 20.8% and 79.2% of the patients, respectively. Adherence to the guideline regarding prescription occurred in 85.30% of the patients. The lowest priced drug class was diuretics and the highest was angiotensin-receptor blockers. In conclusion, the total adherence to the guideline was good; the adherence percentage only slightly decreased with a co-existing comorbidity (such as diabetes mellitus). The use of thiazide diuretics was encouraged because they are well tolerated and inexpensive, and perindopril was still prescribed for diabetic patients since it is relatively cheap (generic drug) and its daily dosage is beneficial.

Evolving pandemic diabetic nephropathy

The expanding impact of chronic kidney disease (CKD) due to pandemic diabetes mellitus is recounted emphasizing its epidemiology that has induced global socioeconomic stress on health care systems in industrialized nations now attempting to proffer optimal therapy for end stage renal disease (ESRD). Strategies to delay and perhaps prevent progression of diabetic nephropathy from minimal proteinuria through nephrotic range proteinuria and azotemia to ESRD appear to have decreased the rate of persons with diabetes who develop ESRD. For those with ESRD attributed to diabetes, kidney transplantation affords better survival and rehabilitation than either hemodialysis or peritoneal dialysis. It is likely that advances in genetics and molecular biology will suggest early interventions that will preempt diabetic complications including renal failure.

A Novel Sartan Derivative With Very Low Angiotensin II Type 1 Receptor Affinity Protects the Kidney in Type 2 Diabetic Rats

Background— Antihypertensive angiotensin II receptor blockers (ARBs) protect the kidney, at least in part, independently of blood pressure lowering. Still, the extent to which blood pressure lowering is related to renoprotection remains unclear.

Methods and Results— 139 newly synthesized ARB-derivatives were assayed for inhibition of advanced glycation (AGEs). The 9 most powerful compounds were then tested for transition metal chelation, angiotensin II type 1 receptor (AT1R) affinity, and pharmacokinetic parameters. R-147176 was eventually selected as it strongly inhibits advanced glycation but is 6700 times less effective than olmesartan in AT1R binding. It is orally bioavailable and toxicologically safe. Despite a minimal blood pressure lowering effect, it provides significant renoprotection in 3 experimental rat models with renal injury, ie, obese, hypertensive, type 2 diabetic rats (SHR/NDmcr-cp), normotensive type 2 diabetic rats (Zucker diabetic fatty), and remnant kidney rats.

Conclusion— R-147176 retains renal protective properties despite a minimal blood pressure–lowering effect. Clearly, the renal benefits of ARBs do not necessarily depend on blood pressure lowering and AT1R affinity, but rather on the inhibition of AGEs and oxidative stress inherent to their chemical structure. R-147176 opens new avenues in the treatment of cardiovascular and kidney diseases.

Renoprotection of Optimal Antiproteinuric Doses (ROAD) Study: a randomized controlled study of benazepril and losartan in chronic renal insufficiency

The Renoprotection of Optimal Antiproteinuric Doses (ROAD) study was performed to determine whether titration of benazepril or losartan to optimal antiproteinuric doses would safely improve the renal outcome in chronic renal insufficiency. A total of 360 patients who did not have diabetes and had proteinuria and chronic renal insufficiency were randomly assigned to four groups. Patients received open-label treatment with a conventional dosage of benazepril (10 mg/d), individual uptitration of benazepril (median 20 mg/d; range 10 to 40), a conventional dosage of losartan (50 mg/d), or individual uptitration of losartan (median 100 mg/d; range 50 to 200). Uptitration was performed to optimal antiproteinuric and tolerated dosages, and then these dosages were maintained. Median follow-up was 3.7 yr. The primary end point was time to the composite of a doubling of the serum creatinine, ESRD, or death. Secondary end points included changes in the level of proteinuria and the rate of progression of renal disease. Compared with the conventional dosages, optimal antiproteinuric dosages of benazepril and losartan that were achieved through uptitration were associated with a 51 and 53% reduction in the risk for the primary end point (P = 0.028 and 0.022, respectively). Optimal antiproteinuric dosages of benazepril and losartan, at comparable BP control, achieved a greater reduction in both proteinuria and the rate of decline in renal function compared with their conventional dosages. There was no significant difference for the overall incidence of major adverse events between groups that were given conventional and optimal dosages in both arms. It is concluded that uptitration of benazepril or losartan against proteinuria conferred further benefit on renal outcome in patients who did not have diabetes and had proteinuria and renal insufficiency.

Management of hypertension in chronic kidney disease

Optimal blood pressure control (<130/80 mm Hg) in patients with chronic kidney disease (CKD), despite being the main objective of conservative therapy, is rarely achieved in clinical practice. A major area of improvement is the correction of the extracellular volume expansion. This goal can be reached by means of dietary salt restriction (100 mEq/d of NaCl). If this intervention fails, hypertension can be treated by thiazide diuretics in patients with mild CKD, whereas loop diuretics at adequate doses are indicated in patients with more advanced CKD. Angiotensin-converting enzyme inhibitors and angiotensin receptor blockers are more effective than other drugs in slowing progression of proteinuric diabetic and nondiabetic CKD. However, the control rates of blood pressure are usually inadequate with antihypertensive therapy including only these drugs; therefore, addition of other classes of antihypertensive drugs is often required.