Risk-benefit ratio of angiotensin antagonists versus ACE inhibitors in end-stage renal disease

Temporal trends in mortality after coronary artery revascularization in patients with end-stage renal disease

BACKGROUND

Recent studies that have assessed the comparative effectiveness between coronary artery bypass grafting (CABG) and percutaneous coronary intervention (PCI) in patients with end-stage renal disease (ESRD) that have included analyses of temporal trends in mortality have noted mixed results.

METHODS

We conducted an observational longitudinal cohort study of all adults with ESRD undergoing CABG or PCI within Kaiser Permanente Northern California. The primary predictor, index period of revascularization, was categorized into 3 periods: 1996-1999 (reference), 2000-2003, and 2004-2008, with the primary outcome being 3-year all-cause mortality. A multivariable Cox regression model with the assumption of independent censoring was used to determine the adjusted relative risk of the primary predictor.

RESULTS

Among 1015 ESRD patients, 3-year mortality showed no significant change in the 2000-2003 period but was lower during the 2004-2008 period with an adjusted hazard ratio of 0.66 (95% confidence interval: 0.49-0.88; trend test p = 0.01). No change in 30-day mortality was noted. Further adjustment for receipt of medications at baseline and after revascularization did not materially affect risk estimates. No significant interactions were observed between the type of revascularization (CABG or PCI) and the period of the index revascularization.

CONCLUSIONS

Among a high-risk cohort of patients with ESRD and coronary artery disease within Kaiser Permanente Northern California who were referred for coronary revascularization by either CABG or PCI, the relative risk of mortality in the 2004-2008 period decreased by 34% compared with the 1996-1999 period, with the benefit primarily in the decrease in late mortality.

Chronic kidney disease after pediatric hematopoietic cell transplant

There are 3 clearly distinct clinical entities that occur after HCT: TMA, idiopathic CKD, and nephrotic syndrome. The potentially independent role of GVHD and chronic inflammation in the development and progression of idiopathic CKD warrants further investigation. CKD after HCT is a relatively common occurrence. As the indications for and number of transplants performed world wide increases, so will the burden of kidney disease. Identifying those patients at risk for the development of CKD will be important for potential intervention and prevention of CKD and progression to end-stage renal disease in this patient population. There are those patients who will develop CKD that is not related to TBI or the conditioning regimen but rather to complications and/or therapy that occur after HCT, specifically aGVHD and cGVHD and prolonged calcinuerin inhibitor use. The burden of management will fall not only to the nephrologists but the oncologist as well to ensure close monitoring of renal function, blood pressure, and urinalyses posttransplant. It may be that our energies have been misdirected in trying to reduce exposure to TBI, and rather we should try to decrease the inflammatory and cytokine effects of GVHD and reduce exposure to calcineurin inhibitors to prevent CKD in this population of patients.

Chronic kidney disease after liver, cardiac, lung, heart-lung, and hematopoietic stem cell transplant

Patient survival after cardiac, liver, and hematopoietic stem cell transplant (HSCT) is improving; however, this survival is limited by substantial pretransplant and treatment-related toxicities. A major cause of morbidity and mortality after transplant is chronic kidney disease (CKD). Although the majority of CKD after transplant is attributed to the use of calcineurin inhibitors, various other conditions such as thrombotic microangiopathy, nephrotic syndrome, and focal segmental glomerulosclerosis have been described. Though the immunosuppression used for each of the transplant types, cardiac, liver and HSCT is similar, the risk factors for developing CKD and the CKD severity described in patients after transplant vary. As the indications for transplant and the long-term survival improves for these children, so will the burden of CKD. Nephrologists should be involved early in the pretransplant workup of these patients. Transplant physicians and nephrologists will need to work together to identify those patients at risk of developing CKD early to prevent its development and progression to end-stage renal disease.

Clinical pharmacokinetics of losartan

Losartan is the first orally available angiotensin-receptor antagonist without agonist properties. Following oral administration, losartan is rapidly absorbed, reaching maximum concentrations 1-2 hours post-administration. After oral administration approximately 14% of a losartan dose is converted to the pharmacologically active E 3174 metabolite. E 3174 is 10- to 40-fold more potent than its parent compound and its estimated terminal half-life ranges from 6 to 9 hours. The pharmacokinetics of losartan and E 3174 are linear, dose-proportional and do not substantially change with repetitive administration. The recommended dosage of losartan 50 mg/day can be administered without regard to food. There are no clinically significant effects of age, sex or race on the pharmacokinetics of losartan, and no dosage adjustment is necessary in patients with mild hepatic impairment or various degrees of renal insufficiency. Losartan, or its E 3174 metabolite, is not removed during haemodialysis. The major metabolic pathway for losartan is by the cytochrome P450 (CYP) 3A4, 2C9 and 2C10 isoenzymes. Overall, losartan has a favorable drug-drug interaction profile, as evidenced by the lack of clinically relevant interactions between this drug and a range of inhibitors and stimulators of the CYP450 system. Losartan does not have a drug-drug interaction with hydrochlorothiazide, warfarin or digoxin. Losartan should be avoided in pregnancy, as is the case with all other angiotensin-receptor antagonists. When given in the second and third trimester of pregnancy, losartan is often associated with serious fetal toxicity. Losartan is a competitive antagonist that causes a parallel rightward shift of the concentration-contractile response curve to angiotensin-II, while E 3174 is a noncompetitive "insurmountable" antagonist of angiotensin-II. The maximum recommended daily dose of losartan is 100mg, which can be given as a once-daily dose or by splitting the same total daily dose into two doses. Losartan reduces blood pressure comparably to other angiotensin-receptor antagonists. Losartan has been extensively studied relative to end-organ protection, with studies having been conducted in diabetic nephropathy, heart failure, post-myocardial infarction and hypertensive patients with left ventricular hypertrophy. The results of these studies have been sufficiently positive to support a more widespread use of angiotensin-receptor antagonists in the setting of various end-organ diseases. Losartan, like other angiotensin-receptor antagonists, is devoid of significant adverse effects.

Treating the patient with kidney failure to reduce cardiovascular disease risk

The reduction of cardiovascular disease risk in kidney failure involves treatment of modifiable risk factors and provision of proven interventions to patients with established disease. Volume status management is key to blood pressure control. Statins are the agents of choice for the treatment of dyslipidemia. Target hemoglobin levels should be achieved using intravenous iron and erythropoietic agents. Combinations of calcium and noncalcium-containing phosphorus binders and vitamin D and its analogues should be used to attain target parathyroid hormone, phosphorus, and calcium phosphorus product levels. beta Blockers and aspirin are recommended in patients with ischemic heart disease and angiotensin-converting enzyme inhibitors (or angiotensin II receptor blockers), and beta blockers are recommended in patients with heart failure with reduced ejection fraction. In patients who require revascularization, studies suggest a survival benefit of coronary artery bypass graft surgery over percutaneous transluminal coronary angioplasty and coronary artery stenting.

Renal handling of angiotensin receptor blockers: clinical relevance

Angiotensin receptor blockers (ARBs), like angiotensin-converting enzyme (ACE) inhibitors, are commonly used in the setting of chronic kidney disease. The use of drugs in this class, or for that matter any drug in the renally compromised patient, should raise consideration of the impact of renal disease on the systemic elimination of the compound. Unlike most of the drugs in the ACE inhibitor class, the compounds making up the ARB class undergo significant hepatic elimination; thus, in the renal failure patient, they are not prone to relevant degrees of systemic accumulation with repetitive dosing. ARBs do not require dose adjustment in renal failure on the basis of their pharmacokinetic pattern; rather, dose reduction should be an empiric process dictated by having reached or exceeded the goal established for blood pressure reduction.

Hyperkalemia, congestive heart failure, and aldosterone receptor antagonism

Hyperkalemia is a common occurrence in patients with congestive heart failure, particularly when renal failure coexists. The level of renal function in congestive heart failure is often difficult to ascertain because good measurement tools for estimation of renal function are not available. Serum creatinine values have often been offered as a good gauge of renal function, although in most cases true renal function is appreciably lower than the estimate derived from a specific serum creatinine value. Thus, patients with congestive heart failure very commonly, particularly in the advanced stages of the disease, have moderate renal insufficiency, either due to specific heart failure-related renal perfusion changes or as the result of renal involvement from the same processes having caused the heart failure, as is the case with diabetes. It is in this setting of mild-to-moderate levels of renal failure that therapies, such as angiotensin-converting inhibitors, angiotensin-receptor blockers, and aldosterone-receptor antagonists, are administered either individually or collectively. Each of these drug classes reduces the homeostatic ability to eliminate ingested potassium loads by the renal route and increase the tendency to evolve into a hyperkalemic state. This is noteworthy because aldosterone-receptor antagonists are increasingly considered as important therapies in the long-term management of heart failure. Spironolactone has been employed in this capacity and a new aldosterone-receptor antagonist, eplerenone, will become available in the near future, which further increases the importance of evaluating and treating the hyperkalemia risk in a timely manner.

Calcium-channel blockers and end-stage renal disease: pharmacokinetic and pharmacodynamic considerations

PURPOSE OF REVIEW

To characterize the pharmacokinetics and pharmacodynamics of the different calcium-channel blockers.

RECENT FINDINGS

Calcium-channel blockers have been in use for some time in the end-stage renal disease population. Their primary use has been as antihypertensive and antianginal therapies. In this regard, they are effective agents. Recently, it has been noted that dialysis-related hypotension occurs less frequently in calcium-channel blocker treated patients. Also, access patency and overall patient survival are improved with calcium-channel blocker therapy.

SUMMARY

Calcium-channel blockers are useful agents for the control of hypertension in end-stage renal disease patients and appear to favorably influence survival in this population. Calcium-channel blockers are not dialyzable and their pharmacokinetics do not substantially change with renal failure therefore they do not require dose adjustment based on level of renal function. Too few studies exist to determine if individual calcium-channel blockers differ in their effects. Prospective, randomized, controlled clinical trials are needed in the end-stage renal disease population to better understand the role of calcium-channel blockers in the excess cardiovascular disease burden of this population.

The pharmacokinetics and pharmacodynamics of angiotensin-receptor blockers in end-stage renal disease

Angiotensin-converting enzyme (ACE) inhibitors and more recently angiotensin-receptor blockers (ARBs) have become popular therapies in the end-stage renal disease (ESRD) patient. The ability of either of these drug classes to reduce blood pressure in the ESRD patient is well accepted; however, there is considerably less information available to guide the clinician in the safe and effective use of these drugs in the ESRD patient with congestive heart failure and/or coronary artery disease. Head-to-head studies in the ESRD patient are lacking for both drug classes. Several pharmacokinetic factors can influence the selection of these drugs, including dialysability and the propensity for systemic accumulation. ACE inhibitors (ACE-Is) and ARBs are recognised as having a range of nonpressor effects that are pertinent to patients with ESRD. Such effects include their ability to decrease both thirst drive and erythropoiesis. These drug classes, though, are distinguishable by the unique adverse effect profile for ACE-Is. As is the case in patients without renal failure, ESRD patients can experience cough and, less frequently, angioneurotic oedema with ACE-Is. In the ESRD population, so-called anaphylactoid dialyser reactions can occur in conjunction with ACE-I use. The use of a drug from within the ARB class carries both less risk and permits a compound with a preferred pharmacokinetic profile limited dialysability and minimal systemic accumulation to be administered. These attributes would favour the increased use of ARBs in this population.

ACE inhibitors and survival of hemodialysis patients

BACKGROUND

Cardiovascular disease is a leading cause of death in patients with end-stage renal disease (ESRD). Hypertension is a major risk factor for cardiovascular complications in these patients. Angiotensin-converting enzyme (ACE) inhibitors are an effective treatment for hypertension in patients with ESRD and are known to improve prognosis in patients with chronic renal failure. We investigated their effect on mortality in patients undergoing long-term hemodialysis therapy.

METHODS

Clinical data for patients on hemodialysis therapy between 1994 and 2000 were reviewed. Patients were grouped according to whether they had been treated with ACE inhibitors.

RESULTS

Sixty patients had been treated with ACE inhibitors (treated group) and 66 patients had not (untreated group). Blood pressure reduction was not significantly different between the treated and untreated groups. Nevertheless, comparing the treated group with the untreated group, mortality was decreased significantly in the treated group, with a risk reduction of 52% (rate ratio [RR], 0.482; confidence interval [CI], 0.25 to 0.91; P < 0.0019). In treated patients 65 years or younger, the absolute risk reduction of mortality was 79% (RR, 0.211; CI, 0.08 to 0.58; P < 0.0006).

CONCLUSION

Although further research is needed, these preliminary findings suggest that ACE inhibitors, independently of their antihypertensive effect, may dramatically reduce mortality among chronic hemodialysis patients 65 years or younger.

Rationale for fixed-dose combinations in the treatment of hypertension: the cycle repeats

Single-drug therapy remains the preferred way to begin treatment of hypertension, although in many patients this is unable to bring blood pressure (BP) to goal levels. Single-drug therapy, even when maximally titrated, is at best only modestly effective in normalising BP in Stage-I or II hypertension, which represents the majority of the hypertensive population. It is increasingly appreciated that the elusive goal of a 'normal' BP is achieved only if multi-drug therapy is employed. This is especially so when considered in the context of today's lower BP goals. The options for multi-drug therapy are quite simple: either fixed-dose combination therapy or drugs added sequentially one after another to then arrive at an effective multi-drug regimen. Advocates exist for both approaches. A considerable legacy, dating to the 1950's, exists for fixed-dose combination therapies. The rationale to this approach has remained constant. Fixed-dose combination therapy successfully reduces BP because two drugs, each typically working at a separate site, block different effector pathways. In addition, the second drug of such two-drug combinations may check counter-regulatory system activity triggered by the other. For example, a diuretic and beta-blocker combination may find the diuretic correcting the salt-and-water retention which occasionally accompanies beta-blocker therapy. The pattern of adverse effects also differs with fixed-dose combination therapy, in part, because less drug is generally being given. In addition, one component of a fixed-dose combination therapy can effectively counterbalance the tendency of the other to produce adverse effects. For example, the peripheral oedema, that accompanies calcium channel antagonist therapy, occurs less frequently when an ACE inhibitor is co-administered. ACE inhibitors improve, if not eliminate, the peripheral oedema associated with calcium channel antagonists because of their proven ability to cause venodilation. In addition, diuretic therapy-induced volume contraction may generate a state of secondary hyperaldosteronism and thereby electrolyte abnormalities such as hypokalaemia and/or hypomagnesaemia. In many cases, the co-administration of either an ACE inhibitor or an angiotensin II receptor blocker with a diuretic corrects the aforementioned electrolyte disturbances. Fixed-dose combination therapy has a proven record of reducing BP. This form of treatment has been available for close to a half-century. Over that period of time, many physicians have taken advantage of this therapeutic approach even when academic opinion was less than charitable to this concept. Academic opinion is rarely immutable and occasionally irrelevant to prescription practice. Prescription practice is driven by many considerations including ease of use, cost and tolerance of a therapy. Most importantly, the therapeutic pathway taken should successfully result in goal BP being reached in a large number of those treated. Unfortunately, despite the simplicity of the concept behind fixed-dose combination therapy, its success will ultimately rest on cost. If made truly cost-competitive, it will gain an increasing share of the hypertensive market. If not, market forces will relegate it to a secondary role for hypertension treatment.

Dosage considerations with perindopril for systemic hypertension

Perindopril erbumine is a once-daily angiotensin-converting enzyme (ACE) inhibitor that effectively lowers systolic and diastolic blood pressure (BP) in patients with mild-to-moderate hypertension. Converted from the prodrug ester perindopril, the active diacid perindoprilat is distributed rapidly and extensively, primarily to tissues with high ACE activity. Its ability to lower BP is comparable to or better than that of other antihypertensive agents, both of its own class and other classes, and its trough-peak ratio is consistently between 75% and 100%, translating into 24 hours of true efficacy per dose. First-dose hypotension caused by an initial acute BP depression occurs less frequently with perindopril than with other ACE inhibitors, an advantage in volume-contracted patients and those whose BP is angiotensin II dependent, such as patients with congestive heart failure. A missed-dose study showed that most of the antihypertensive effect of perindopril remains for 24 to 48 hours after dosing, a characteristic that confers protection to patients who miss a dose. Perindopril improves the distensibility and compliance of large and small arteries, which are compromised in hypertension, and can effect vascular remodeling by a mechanism independent of BP lowering. The clinical implications of these effects are being investigated in large trials. Perindopril is well tolerated in the elderly, and combination therapy with a diuretic was shown to yield significant additional BP reduction. Perindoprilat is cleared renally; dosage should be adjusted in patients with renal impairment.

Pharmacotherapy in congestive heart failure: Angiotensin-converting enzyme inhibitors and angiotensin receptor blockers in congestive heart failure: do they differ in their renal effects in man?

Angiotensin-converting enzyme (ACE) inhibitors are used in the management of a wide range of cardiovascular conditions, including congestive heart failure (CHF). Although the experimental evidence in support of their use in CHF is incontrovertible, their pattern of usage has failed to keep pace with the research findings. One factor that has fueled the hesitancy to use ACE inhibitors in CHF has been the concern that renal function might worsen upon their receipt. Although the glomerular filtration rate may decline when ACE inhibitor or angiotension receptor blocker therapy is started in CHF, in most cases it is not a reason to discontinue therapy other than temporarily. Although ACE inhibitors and angiotensin receptor blockers may differ theoretically in their renal effects, published information to date has not shown such a difference. (c)2001 by CHF, Inc.

Pharmacotherapy in congestive heart failure: Hyperkalemia in congestive heart failure

Hyperkalemia is not an uncommon occurrence in the congestive heart failure patient, particularly when renal failure coexists. Hyperkalemia in CHF is typically medication-related. Its occurrence is inevitably linked to the simultaneous ingestion of angiotensin-converting enzyme inhibitors and beta-blockers, and more recently, aldosterone receptor antagonists, such as spironolactone. The most devastating consequence of hyperkalemia is its cardiotoxicity that can be fairly insidious in its rate of development. The therapy of hyperkalemia in congestive heart failure can involve both acute and semiacute management phases. Acute hyperkalemia management includes measures that block the adverse membrane effects of hyperkalemia, such as intravenous calcium administration, and efforts to shift potassium intracellularly, such as occurs with intravenous bicarbonate and/or inhaled beta-agonists. Semiacute management of hyperkalemia includes measures to increase urinary potassium excretion and administration of binding resins, such as Kayexalate®. Prevention is the cornerstone of hyperkalemia management in the heart failure patient and requires that careful attention be directed to both identifying exogenous sources of potassium and pinpointing the maximum tolerable dose of either an angiotensin-converting enzyme inhibitor or an angiotensin-receptor blocker. (c)2001 by CHF, Inc.