Postmarketing surveillance of enalapril. II: Investigation of the potential role of enalapril in deaths with renal failure

Current approaches to renovascular hypertension

This article examines the status regarding prevalence, mechanisms, clinical manifestations and management of renovascular hypertension at this point in time. It should be viewed as a work in progress. As with most complex conditions, clinicians must integrate the results of published literature studies while considering each patient's specific features and comorbid disease risks. Beyond identifying renovascular disease as a cause of secondary hypertension, one must manage renal artery stenosis (RAS) itself as an atherosclerotic vascular complication. This disease warrants follow-up regarding progression and potential for ischemic tissue injury. These elements often determine the role and timing for revascularization. In this respect, atherosclerotic renal artery stenosis is analogous to progressive carotid or aortic aneurysmal disease.

Potential side effects of renin inhibitors – mechanisms based on comparison with other renin–angiotensin blockers

Angiotensin (Ang) II plays important roles in the development of hypertension and cardiovascular and renal injury. Pharmaceutical approaches to block its activity led to the development of angiotensin-converting enzyme inhibitors and angiotensin receptor blockers. Numerous trials have documented their efficacy in controlling blood pressure, minimising left ventricular remodelling, preventing progression to heart failure, ameliorating proteinuria and retarding renal disease progression. Although they are considered safe in general, there remain concerns about the potential for adverse events in certain target populations. Recently, several novel, low molecular weight renin inhibitors without the extended peptide-like backbone of previous renin inhibitors were developed with favourable pharmacokinetic properties. They have been shown to successfully reduce Ang II levels in normal volunteers and to lower blood pressure in patients with mild-to-moderate hypertension. In this review, the authors summarise current knowledge about these renin inhibitors.

Hyperkalemia: a review

Potassium is the principal intracellular cation, and maintenance of the distribution of potassium between the intracellular and the extracellular compartments relies on several homeostatic mechanisms. When these mechanisms are perturbed, hypokalemia or hyperkalemia may occur. This review covers hyperkalemia, that is, a serum potassium concentration exceeding 5 mmol/L. The review includes a discussion of potassium homeostasis and the etiologies of hyperkalemia and focuses on the prompt recognition and treatment of hyperkalemia. This disorder should be of major concern to clinicians because of its propensity to cause fatal arrhythmias. Hyperkalemia is easily diagnosed, and rapid and effective treatments are readily available. Unfortunately, treatment of this life-threatening condition is often delayed or insufficiently attentive or aggressive.

Can dual blockade of the renin–angiotensin system reduce progression of kidney disease beyond monotherapy?

It is well-accepted that therapies directed at the renin-angiotensin system (RAS) reduce the progression of chronic kidney disease. Angiotensin-converting enzyme (ACE) inhibitors and the angiotensin receptor blockers (ARBs) are currently available to interrupt this cascade. Their positive actions result from better blood pressure control, a reduction in glomerular capillary pressure and a decrease in proteinuria. Blockade of the RAS may also reduce renal scarring by blunting direct pro-fibrotic effects of angiotensin II and aldosterone. Although these drugs successfully reduce urinary protein excretion and improve renal survival, a significant number of patients continue to progress to end stage renal disease. It is possible, however, that dual blockade of the RAS with an ACE inhibitor and an ARB might offer further benefit beyond using either agent alone. Optimally, the goal should be to completely halt the progression of kidney disease. With these concepts in mind, this paper will review the RAS and its effects on the kidney. The efficacy and safety of dual RAS blockade in proteinuric renal diseases will be examined. Finally, recommendations for utilising combined therapy with ACE inhibitors and ARBs will be provided.

A design for prescription-event monitoring in Japan (J-PEM)

OBJECTIVES

To present a design for Prescription-Event Monitoring in Japan (J-PEM).

METHODS

In J-PEM, pharmacists are asked to register patients who are prescribed the 'test drug' or a 'control drug' for the first time ever, the drug, and prescribing physician. Although J-PEM does not identify all users of a drug, this method provides concurrent controls. In J-PEM, a questionnaire for the pharmacist and one for the prescribing physician are mailed 6 months after the drug to be monitored is first prescribed to a patient. Doctors and pharmacists are asked to report events that occurred in the patient after the drug was prescribed. The questionnaire for the physician includes questions that are specific to the class of drug that was prescribed, to obtain information on possible confounding variables. Pharmacists are requested to give information on all concomitant drugs used by the patient during or for a part of the period that the patient was taking the drug to be monitored.

RESULTS AND CONCLUSIONS

Compared with the UK PEM, the weakness of J-PEM is its inability to identify all users of a drug, and its strengths are the availability of concurrent controls and a relatively large amount of information per patient.

The J-curve in hypertension

The J-curve debate has continued for 25 years. Dependency upon observational and retrospective studies has confused the issue; only the full publication of data from the prospective, randomized Hypertension Optimal Treatment (HOT) study has thrown genuine light on the problem. Many examples of the J-curve relationship between blood pressure and cardiovascular/noncardiovascular events are due to reverse causality, where underlying disease (eg, poor left ventricular function, poor general health, poorly compliant/stiff arteries) is the cause of both the low blood pressure and the increased risk of both cardiovascular and noncardiovascular events. The J-curve in patients with stiff arteries (wide pulse pressure) may be exacerbated by treatment. From the full publication of the HOT study database it is now reasonable to conclude that for nonischemic hypertensive subjects the therapeutic lowering of diastolic blood pressure (DBP) to the low 80s mm Hg is beneficial, but it is safe (though unproductive) to go lower. However, in the presence of coronary artery disease (limited coronary flow reserve) there is a J-curve relationship between treated DBP and myocardial infarction, but not for stroke. In such high-risk (for myocardial infarction) cases it would be prudent to avoid lowering DBP to below the low 80s mm Hg.

Determinants of impaired renal function with use of nonsteroidal anti-inflammatory drugs: the importance of half-life and other medications

PURPOSE

Nonsteroidal anti-inflammatory drugs (NSAIDs) may interfere with renal function, but little is known about the effects of the half-life of these agents, or the use of other medications, on renal function.

SUBJECTS AND METHODS

Medication use was assessed during a standardized interview in a cross-sectional study of 802 patients undergoing total joint replacement because of osteoarthritis. Preoperative blood samples were used to estimate creatinine clearance using a standard formula that takes age, sex, and weight into account. Impaired renal function was defined as an estimated creatinine clearance less than 60 mL/min (fifteenth percentile). Multivariable logistic regression was used to estimate the adjusted odds ratios (OR) and 95% confidence intervals (CI) for the association between NSAID use (alone or in combination with diuretics or angiotensin-converting enzyme [ACE] inhibitors) and impaired renal function.

RESULTS

NSAID use per se was only marginally associated with impaired renal function (OR = 1.4; 95% CI, 0.9 to 2.2). This association was almost exclusively the result of the use of NSAIDs with a half-life of 4 or more hours (OR = 2.6; 95% CI: 1.2 to 5.7). Patients who used diuretics with NSAIDs (OR = 3.7; 95% CI: 1.7 to 8.3) or without NSAIDs (OR = 3.5; 95% CI: 1.6 to 7.6) had a higher risk of impaired renal function than did patients using NSAIDs alone (OR = 1.6) or none of these drugs (reference). A similar but less pronounced pattern was observed for ACE inhibitors.

CONCLUSION

NSAID-associated impaired renal function seems to be mainly the result of compounds with intermediate-long half-life. We found no evidence that the adverse effects of diuretics and ACE inhibitors on renal function were greater in those who also used NSAIDs.

Prescription-event and other forms of epidemiological monitoring of side-effects in the UK

The post-marketing surveillance (PMS) of drugs is necessary because of the limited size of the clinical safety database at the time of marketing. The principal hypothesis-generating methods of PMS are spontaneous reporting (e.g. the yellow card) and Prescription Event Monitoring. These methods are discussed in this chapter and certain basic pharmacoepidemiological issues that are relevant are briefly reviewed.

Perindopril postmarketing surveillance: a 12 month study in 47,351 hypertensive patients

AIMS

To gain information on serious adverse events in a large number of patients exposed to perindopril.

METHODS

Four thousand seven hundred and eighty-eight general practitioners throughout France collaborated in the recruitment of 47,351 patients for a 12 month postmarketing study. Data collection was undertaken by company representatives under the supervision of nine regional medical officers. Computerised data entry was performed by six pharmaceutical officers. Serious adverse events were later individually reviewed medically.

RESULTS

Withdrawals due to adverse events occurred in 6.1% of female and 3.2% of males patients. The ascertainment of adverse events in this study approved satisfactory, as shown by the reported incidence of cough, which was 11.3% in women and 7.8% in men, this being compatible with the best estimates of the true incidence of cough during ACE-inhibitor therapy. Serious adverse reactions-anaphylaxis and blood dyscrasias-were rare.

CONCLUSIONS

This study successfully followed a large cohort of patients treated with perindopril and failed to demonstrate any unexpected hazards.

Adverse effects of the angiotensin-converting enzyme inhibitors

OBJECTIVE

To review current literature relating to the adverse effects of the angiotensin-converting enzyme (ACE) inhibitors.

DATA SOURCES

Online drug information sources, including MEDLINE (1966-November 1994), Iowa Drug Information Service, and the Australian Medical Index (AMI), were used to identify relevant literature, including reviews.

DATA EXTRACTION

Data were extracted from studies described in the English-language literature dealing with the adverse effects of ACE inhibitors. Comprehensive reviews and relevant case reports also were included.

DATA SYNTHESIS

Important adverse effects of ACE inhibitors include first-dose hypotension, renal dysfunction, hyperkalemia, and cough. Less common adverse effects include angioedema, hepatotoxicity. Skin rashes, and dysgeusia. ACE inhibitors also are associated with adverse fetal effects; thus, this class of drugs in contraindicated in pregnancy. Some adverse effects of ACE inhibitors are predictable on the basis of the fundamental pharmacology of this class of drugs. However, other effects are idiosyncratic in nature, although these reactions are generally much less common.

CONCLUSIONS

Attention to the principles of risk assessment, risk immunization, and patient monitoring are important when ACE inhibitor therapy is used for any indication. Provided these steps are taken. ACE inhibitors are generally a safe and effective class of drugs.

European postmarketing surveillance of ramipril in hypertension. 1. Feasibility and study cohort

A prospective observational cohort study of the angiotensin inhibitor, ramipril, was undertaken in four countries within the European Community-Netherlands, United Kingdom, Germany and Belgium. A total of 10,377 consecutive patients with essential hypertension were recruited to the study with the aim of follow-up for one year. Overall 37% of doctors who agreed to participate in the study actually enrolled at least one patient. One third of the doctors who enrolled patients in the study entered two thirds of patients studied. Some 15% of participating males and 27% of females were aged over 70 years. Newly diagnosed hypertensives comprised 22% of the study cohort, the proportion being highest in UK and Netherlands, whereas 53% were established hypertensives of two or more years' duration, the proportion being highest in Germany and Belgium. There were substantial differences among the participating countries in the concurrent treatment these patients were receiving for hypertension, with two or more co-therapies being most frequent in Germany and Belgium. There were also substantial differences in co-therapies for concurrent diseases among the participating countries, reflecting both standard therapeutic practices in local areas and differences in marketing of drugs in the different countries. This report describes the initial findings of this multinational study and emphasises the need to consider several major potentially confounding variables in the analysis of the outcome events both in this study and in other collaborative observational international monitoring schemes for adverse drug reactions.

ACE inhibitors. Drug interactions of clinical significance

ACE inhibitors are used widely in the treatment of hypertension and congestive heart failure, but there is only limited information on adverse interactions between ACE inhibitors and other cardiovascular or noncardiovascular drugs. The present article provides an overview of this issue, with emphasis on those interactions having the greatest clinical implications. In patients who have been sodium and/or volume depleted by thiazide or loop diuretics, the additional use of ACE inhibitors can lead to an excessive reduction in blood pressure and symptomatic hypotension. An increase in serum potassium levels may occur after coadministration of potassium-sparing diuretics and ACE inhibitors, resulting in hyperkalaemia especially in patients with renal insufficiency. The incidence of acute renal failure may be associated with ACE inhibitor therapy when these drugs are combined with nonsteroidal anti-inflammatory agents and given to patients whose renal function becomes increasingly dependent on angiotensin II and prostaglandins. There is some evidence, albeit scant, linking ACE inhibitors with the induction of lithium toxicity in patients maintained on lithium, and with the occurrence of severe hypersensitivity reactions in patients undergoing haemodialysis, venom immunisation or concomitant allopurinol therapy.

Acute renal failure with ACE inhibition in aortic coarctation

A 43 year old man with inoperable aortic coarctation and severe hypertension requiring near maximal anti-hypertensive treatment was admitted in severe heart failure. After 2 weeks of treatment the heart failure and blood pressure were incompletely controlled and angiotensin converting enzyme (ACE) inhibitor was started. Serum creatinine was normal before starting the ACE inhibitor and on discharge from hospital. The patient was re-admitted a week later with gross fluid retention and in renal failure. In the absence of alternative causes, a diagnosis of ACE inhibitor-induced renal failure was made and treatment was stopped. The patient required haemodialysis for 2 days and within 1 week the renal function had reverted to normal and has remained so for 1 year. We propose that the renal haemodynamics in severe aortic coarctation are similar to those in bilateral severe renal artery stenosis and advise caution in the use of ACE inhibitors for adults with aortic coarctation.

Efficacy and dosage of enalapril in congenital and acquired heart disease

In a tertiary referral centre 63 patients underwent 67 treatment periods with enalapril. The median age was 5.4 months. All children had signs of heart failure: congestive cardiac failure with breathlessness at rest was present in 88%. Haemodynamic groups were left-to-right shunt (n = 15), impaired ventricular function (n = 14), after cardiac surgery (n = 23), valvar regurgitation (n = 12), and hypertension (n = 3). Serial clinical, radiological, and laboratory data were used to judge outcome. The mean (SD) maximal dose was 0.30 (0.21) mg/kg/day. Thirty nine (58%) patients improved, 20 (30%) showed no improvement, and eight (12%) had side effects requiring discontinuation of enalapril. Renal failure in eight patients was related to young age, low weight, and left-to-right shunt group. Three patients died in congestive heart failure with renal failure. Enalapril was clinically safe and effective for children with cardiac failure secondary to ventricular impairment, valvar regurgitation, or after cardiac surgery. Renal failure was a problem in young infants with left-to-right shunts.

Converting enzyme inhibition in rabbits: effects on sodium and water intake/excretion and blood pressure

Earlier studies in rabbits revealed that in this species, in contrast to most other species studied, water intake was not influenced by injection or infusion of angiotensin II (ANG II). In order to establish whether ANG II has any role in the regulation of water intake of rabbits, a comprehensive study of the effect of converting enzyme inhibition was undertaken. Enalaprilat was given systemically in various doses to sodium- and water-replete, sodium-deplete, and water-deprived rabbits, and the intake and excretion of water and sodium was measured. In replete rabbits systemic injection of enalaprilat, 8 mg/kg and 8 micrograms/kg, but not 0.8 mg/kg, was followed by increased daily water intake. In sodium-deplete rabbits injection of enalaprilat, 80 mg/kg, was followed by water drinking within 1 h, and daily sodium intake was reduced. Systemic administration of ANG II increased, but did not restore to control level the sodium appetite of sodium-deplete rabbits attenuated by 80 mg/kg enalaprilat. Rabbits deprived of water for 24 h, however, drank the same amount of water after injection of vehicle or enalaprilat, 80 and 8 mg/kg. The efficacy of converting enzyme inhibition was also tested by measuring the blood pressure response to ANG I. Blood pressure responses revealed that in replete animals converting enzyme activity was depressed below control levels for 30 h after injection of 80 mg/kg enalaprilat. In sodium-deplete rabbits blood pressure fell following injection of 80 mg/kg enalaprilat and did not return to control level until 48 h after the injection.(ABSTRACT TRUNCATED AT 250 WORDS)

Drug-induced renal disease

OBJECTIVE

To review drug-induced renal disease with emphasis on current issues and practical problems with commonly used agents.

DATA SOURCES

English language literature search using MEDLINE, Index Medicus, textbook articles and relevant reviews.

STUDY SELECTION

Drugs in common use were reviewed in detail. Uncommonly used drugs or those with only a few reports of nephrotoxicity were excluded from this review.

DATA SYNTHESIS

The clinical patterns of nephrotoxicity include an episode of acute deterioration of renal function, chronic renal failure and proteinuria which may be severe enough to cause the nephrotic syndrome. Diagnosis is made by clinical suspicion, distinctive clinical patterns and usually improvement in renal function on drug withdrawal.

CONCLUSION

A high index of suspicion is necessary to detect drug-induced renal disease particularly with increasing availability of over-the-counter drugs. Drugs should always be suspected of causing renal disease where no alternative cause is obvious. When any doubt exists the agent in question should be withdrawn.

Angiotensin converting enzyme (ACE) inhibitors and renal function. A review of the current status

Angiotensin converting enzyme (ACE) inhibitors are well established in the treatment of hypertension and cardiac failure. Experimental studies in rats have suggested that these agents may protect renal function in chronic nephropathy by a mechanism other than simply lowering the systemic blood pressure. In human studies of incipient diabetic nephropathy, worsening of microalbuminuria was prevented during 3 years of ACE inhibition. ACE inhibitors reduce arterial blood pressure in chronic nephropathy, and may cause a fall in glomerular filtration rate. In diabetic nephropathy, proteinuria was reduced by 2 months' treatment with enalapril to less than half of the values obtained in a control group treated with metoprolol. Nonrandomised trials have suggested that ACE inhibitors may slow the deterioration of renal function, but no comparisons with other antihypertensive agents in prospective studies have been published to date. In chronic renal failure, ACE inhibitors may worsen anaemia and hyperkalaemia. Renovascular hypertension can be treated with ACE inhibitors, but the treatment may lead to a compromised renal function. The dosage of these drugs should be reduced in renal failure and therapy should be started cautiously in this setting, with close monitoring of blood pressure, renal function and plasma potassium.

Angiotensin converting enzyme inhibitors and moderate hypertension

Recently there has been extensive development of orally active angiotensin converting enzyme (ACE) inhibitors in addition to those already marketed, for example, captopril, enalapril, lisinopril and ramipril. It was initially thought that ACE inhibitors were likely to be most useful as antihypertensive agents in conditions in which circulating renin and angiotensin II were elevated. However, it is now clear that they can also lower arterial pressure when plasma renin is not high. In addition, they have beneficial effects in cardiac failure. Thus, captopril, enalapril, lisinopril and ramipril can be used in the treatment of mild to moderate hypertension either alone or in conjunction with diuretics or calcium antagonists. Broadly speaking, efficacy appears to be similar to that of beta-blockers or diuretics. Unfortunately, however, there are no long term studies comparing one ACE inhibitor with another or with other classes of antihypertensive agents. Furthermore, there are no prognostic studies which show that use of ACE inhibitors reduces morbidity or mortality in hypertension. Many new ACE inhibitors are undergoing clinical assessment, including alacepril, cilazapril, fosenopril, perindopril, quinapril and ramipril. The drugs vary, in that some exist in the active form whereas others are prodrugs which are converted to the active agent following absorption. In addition they each possess one of several ligands, for example, carboxyl, phosphinyl or sulfhydryl groups, and so vary in their affinity for ACE. Although many of these agents are renally excreted, a small number are metabolised via the liver (e.g. quinapril and spirapril) and this may prove advantageous in the presence of renal impairment. In common with captopril and enalapril, the new ACE inhibitors inhibit the renin-angiotensin system and initial results suggest that they are effective in lowering blood pressure in essential hypertension. Furthermore, they reduce systemic vascular resistance in the absence of a reflex tachycardia. There are a number of adverse effects which are attributable to the pharmacological mechanism of the ACE inhibitors as a group; these include hypotension, particularly in patients with high renin levels, prior diuretic use, renal impairment or in the elderly. Additional adverse effects may relate to chemical structure. The high incidence of adverse effects noted in early studies related to excess dosage and to the presence of a sulfhydryl group, which the more recently developed ACE inhibitors lack. The adverse effects most commonly reported with established and new ACE inhibitors include headache and fatigue, cough, skin rashes, hypotension and diarrhoea. As a group, ACE inhibitors have an acceptable but not negligible adverse effect burden.(ABSTRACT TRUNCATED AT 400 WORDS)

Prescription-event monitoring: methodology and recent progress

Event monitoring was first suggested 25 years ago as a way of detecting adverse reactions to drugs. Prescription-event monitoring (PEM), which has been developed by the Drug Safety Research Unit, is the first large-scale systematic post-marketing surveillance method to use event monitoring in the U.K. PEM identifies patients, who have been prescribed a particular drug, and their doctors from photocopies of National Health Service prescriptions which are processed centrally in England. A personalized follow-up questionnaire ("green form") is mailed to each patient's general practitioner, usually on the first anniversary of the initial prescription, asking for information about the patient, especially any "events" that he or she may have experienced since beginning treatment with the drug. The methodology of PEM is presented, together with examples of analyses that can be performed using results from recent studies. The problems and benefits of PEM are discussed.

Enalapril. An update of its pharmacological properties and therapeutic use in congestive heart failure

Enalapril provides significant haemodynamic, symptomatic and clinical improvement when added to maintenance therapy with digitalis and diuretics in patients with congestive heart failure [NYHA (New York Heart Association) classes II to IV]. These effects are not attenuated during long term therapy. More significantly, a clinical study demonstrated that enalapril reduces mortality when added to established therapy in patients with severe congestive heart failure (NYHA class IV) refractory to digitalis, diuretics and other vasodilators. Thus, ACE inhibitors such as enalapril offer a significant advance in the treatment of congestive heart failure. Because these drugs improve symptoms in patients with classes II to IV failure, and reduce mortality in patients with severe heart failure, they should be considered as first choice adjuvant therapy when a vasodilator is needed in addition to conventional treatment with digitalis and diuretics.

Postmarketing surveillance of enalapril. I: Results of prescription-event monitoring

To identify and measure the incidence of adverse effects of the angiotensin converting enzyme inhibitor enalapril 13,713 patients were studied for one year by prescription-event monitoring. Precise information about the duration of treatment was available for 12,543 patients. The frequency of many events was calculated, including dizziness (483 patients; 3.9%), persistent dry cough (360; 2.9%), headache (310; 2.5%) hypotension (218; 1.7%), and syncope (155; 1.2%). Less common reactions included angioedema, urticaria, and muscle cramps. Altogether 1098 (8%) patients died and the notes of 913 of them (83%) were obtained for detailed scrutiny. With the exception of a few patients with renal failure who deteriorated during treatment (reported on separately), no death was attributed to enalapril. Enalapril was considered to be effective, even in patients with advanced cardiac failure. These results for enalapril are reassuring and provide further evidence of the value of prescription-event monitoring.