Double-blind comparison of captopril and enalapril in mild to moderate hypertension

Therapeutic substitution post-patent expiry: the cases of ACE inhibitors and proton pump inhibitors

This paper examines whether there is a switch in total (originator and generic) consumption after generic entry from molecules that face generic competition towards other molecules of the same class, which are still in-patent. Data from six European countries for the time period 1991 to 2006 are used to study the cases of angiotensin-converting enzyme inhibitors and proton pump inhibitors. Empirical evidence shows that patent expiry of captopril and enalapril led to a switch in total (off-patent originator and generic) consumption towards other in-patent angiotensin-converting enzyme inhibitors, whereas patent expiry of omeprazole led to a switch in consumption towards other proton pump inhibitors. This phenomenon makes generic policies ineffective and results in an increase in pharmaceutical expenditure due to the absence of generic alternatives in the market of in-patent molecules.

Intravenous vasodilator therapy in congestive heart failure

The prevalence of congestive heart failure (CHF) is increasing in the US and worldwide, partly because patients are living longer. Treatment of CHF is mostly on an outpatient basis, but inpatient care is required for decompensated CHF, acute CHF or poor response to outpatient treatment. Control of symptoms is usually achieved by diuresis. Intravenous (IV) vasodilators are an important adjunct to the inpatient treatment of CHF. They work mainly by reducing the afterload on the myocardium although preload reduction also occurs. After clinical stabilisation, the goal is to switch to a maintenance oral regimen to be continued as outpatient therapy. The range of IV vasodilators available for inpatient treatment of CHF includes nitrates, phosphodiesterase inhibitors, dobutamine, morphine, ACE inhibitors, B-type natriuretic peptides and endothelin receptor antagonists. As each agent may have a different mechanism or site of action, each agent may affect preload, contractility or afterload to a different extent and it may be desirable to choose one over the other in a particular clinical setting. Examples of standard therapy include dobutamine, milrinone and nitroglycerin. Nesiritide, a B-type natriuretic peptide, is a newer vasodilator and US FDA approved for use in acute CHF. However, most studies with this agent have been in small numbers of patients with anecdotal findings. Larger studies are warranted to pinpoint the efficacy and adverse effects of this agent. It is primarily used to reduce the acuity of decompensated CHF on admission to hospital.Endothelin receptor antagonists show promise in the management of acute CHF, but continue to be investigational. Long-term data on their efficacy and safety are limited. None of the endothelin receptor antagonists are FDA approved for use in patients with CHF.

Comparison of enalapril to captopril by 24-hour ambulatory blood pressure monitoring

The efficacy of a once-daily dose of enalapril was compared with a thrice-daily dose of captopril in an open-label, randomized parallel group study of 27 hypertensive patients. The patients were monitored using conventional measurements of blood pressure and with 24-hour ambulatory blood pressure monitoring at baseline and after 12 weeks of therapy. The end points were 24-hour, daytime, and nighttime mean blood pressure values and the percentage of elevated systolic and diastolic measurements, reflecting the "hypertensive load." Enalapril reduced mean 24-hour systolic blood pressure by 18 mmHg and diastolic blood pressure by 11 mmHg. The comparative values for captopril were 9 mmHg and 2 mmHg, respectively. The mean daytime systolic blood pressure was reduced by 20 mmHg with enalapril versus 7 mmHg with captopril; the diastolic values were lowered by 11 mmHg with enalapril versus 4 mmHg with captopril. The mean nighttime systolic blood pressure was lowered by 16 mmHg with enalapril versus 12 mmHg with captopril; the diastolic values were reduced by 10 mmHg with enalapril and 5 mmHg with captopril. No major side effects were recorded in either group. A single daily 20-mg dose of enalapril, therefore, proved to be equipotent or superior to 75 mg of captopril administered in three divided doses.

Hypertension

An estimated 58 million Americans are at increased risk of morbidity and premature death due to high blood pressure (BP) and require some type of therapy or systematic monitoring. This article focuses on recent advances in our understanding of the pathogenesis of hypertension, new approaches to the diagnosis and treatment of secondary hypertension, and current views of the most appropriate nonpharmacologic and pharmacologic therapy for essential hypertension. In view of the extremely high prevalence of the disorder, emphasis is placed on efficient and cost-effective strategies for diagnosing and managing the hypertensive patient. Recent evidence indicates that nonpharmacologic therapy, including dietary potassium and calcium supplements, reduction of salt intake, weight loss for the obese patient, regular exercise, a diet high in fiber and low in cholesterol and saturated fats, smoking cessation, and moderation of alcohol consumption produces significant sustained reductions in BP while reducing overall cardiovascular risk. Accordingly, nonpharmacologic antihypertensive therapy should be included in the treatment of all hypertensive patients. In persons with mild hypertension, nonpharmacologic approaches may adequately reduce BP, thereby avoiding the expense and potential side effects of drug therapy. In patients with more severe hypertension, nonpharmacologic therapy, used in conjunction with pharmacologic therapy, can reduce the dosage of antihypertensive medications necessary for BP control. Patients treated with nonpharmacologic therapy only should be followed closely, and if BP control is not satisfactory, drug therapy should be added. The large number of drugs available for use in hypertension treatment, coupled with our rapidly expanding knowledge of the pathophysiology of hypertension and of the adverse effects of these drugs in individual patient groups, make it possible to individualize antihypertensive treatment. When used as monotherapy, most agents effectively lower BP in the majority of patients with mild or moderate essential hypertension. Thus, a single agent from one of four classes: diuretics, angiotensin-converting enzyme inhibitors, calcium channel blockers, and beta-adrenergic blockers, usually provides effective BP control with minimal side effects in most patients. Therapy should be initiated with the agent most likely to be effective in BP lowering and best tolerated. If the initial agent is ineffective at maximal recommended therapeutic doses or has undue side effects, an alternative agent from another class should be tried. When monotherapy is unsuccessful, a second agent, usually of a different mechanism of action, should be

ACE inhibitors and diuretics. The benefits of combined therapy for hypertension

Hypertension and its consequences continue to threaten the health of as many as 60 million Americans. Effective control of blood pressure can be achieved in some patients with a single agent and in many of the remainder with combination therapy. The ideal combination regimen is one that is at least as effective as a single agent, has minimal or no side effects, has a wide therapeutic index, is simple to administer, and is effective in a wide variety of patient populations. When used in combination, the thiazide diuretics and the angiotensin-converting enzyme inhibitors have been shown to improve blood pressure reduction over either drug used alone. In addition, the combination is effective in a wide range of patient populations (blacks and whites, young and old) and is accompanied by fewer adverse metabolic effects than the thiazides alone. Finally, the combination has a more positive impact on quality of life than other combinations involving the thiazide diuretics.

Comparison of once-daily captopril or enalapril in mild essential hypertension

The purpose of this study was to assess the effect of a daily low dose of the angiotensin-converting enzyme (ACE) inhibitors, captopril or enalapril, in mild essential hypertension. Nine men with seated diastolic blood pressure between 95 and 104 mm Hg on placebo participated in the study. After one month of placebo, captopril 25 mg was administered; blood pressure, heart rate, ACE activity and plasma renin activity were measured hourly for 4 hours. Each patient then received captopril 50 mg once daily for 8 weeks and similar measurements were made 24 hours post-dose every 2 weeks. After another month of placebo, the identical protocol was repeated after enalapril 5 mg. Although blood pressure and ACE activity decreased significantly (P less than 0.05) within 2-4 hours of the acute doses of each inhibitor, neither captopril or enalapril produced significant reductions 24 hours after the small daily dose. Thus, neither ACE inhibitor alone was adequate to control blood pressure in mild hypertension when given once daily during 8 weeks of treatment.

Clinical experience with labetalol and enalapril in combination in patients with severe essential and renovascular hypertension

Severe hypertension may be a difficult management issue, and it often requires therapy with multiple drugs at frequent dosing intervals. We report on the antihypertensive effects of the alpha-beta adrenergic blocking agent, labetalol, in combination with enalapril, a long-acting angiotensin-converting enzyme inhibitor, administered to 14 patients with severe hypertension (nine of whom had nephrosclerosis or renal artery stenosis) on other antihypertensive drug therapies. Blood pressure (BP), heart rate (HR), hematologic and blood chemistry values, and adverse side effects were monitored at 24 hours, 1 week, and 4 weeks of therapy. Rapid titration of the drugs was performed in the hospital in 10 patients; four were managed closely as outpatients. Following one month of combination therapy blood pressure decreased from 212 +/- 31/120 +/- 16 mm Hg at baseline to 155 +/- 19/86 +/- 12 mm Hg, and heart rate declined from 86 +/- 18 bpm to 70 +/- 16 bpm. Ten of the 14 patients (71%) maintained good BP control (BP less than 140/90 mm Hg) with no additional treatment. Serum potassium, creatinine, blood urea nitrogen concentrations, and hematologic parameters did not significantly change in 13 of 14 patients. Three patients developed symptomatic postural hypotension; in one patient this side effect resulted in discontinuation from the study. These data suggest that combination therapy with labetalol and enalapril is effective in lowering BP in patients with severe essential or renovascular hypertension. An additional advantage of this regimen is the twice-daily dosing interval, which may promote better long-term compliance.

Angiotensin-converting enzyme inhibitors

There is convincing evidence that ACE inhibitors, alone or in combination with a diuretic, effectively lower blood pressure in patients with all grades of essential or renovascular hypertension and that they are of particular benefit as adjunctive therapy in patients with congestive heart failure. The hemodynamic, hormonal and clinical effects of the presently available ACE inhibitors, captopril and enalapril, are comparable and their side effect profiles are extremely favorable. One important difference between the two oral ACE inhibitors, however, is their pharmacokinetics; enalapril's action is slower to begin and is of longer duration. Compared with other agents, ACE inhibitors offer important advantages, among them an improved feeling of well being. It is, therefore, expected that ACE inhibitors will gain greater acceptance by patients and physicians in the future.

Issues with antihypertensive therapy: safety perspectives

The benefits of treating hypertension have been documented by several long-term studies that have shown a decreased incidence of morbidity and mortality associated with stroke, left ventricular failure, and renal insufficiency. With the large number of antihypertensive drugs currently available, several safety factors need to be considered when initially choosing a regimen so as not to adversely influence the potential benefits of blood pressure control. Antihypertensive agents should be chosen based on their hemodynamic profile, the absence of adverse metabolic effects and subjective side effects, and the presence of beneficial effects on the patients' quality of life. Thiazide diuretics and beta-blocking agents have often been recommended as initial therapy in patients with mild to moderate hypertension. However, thiazide diuretics may be less desirable in certain patients because of their effects on lipids, potassium, and glucose tolerance; beta-blocking agents are not ideal for some patients because of their effects on lipids, exercise tolerance, and overall quality of life. The angiotensin-converting enzyme inhibitors, selective alpha 1-blocking agents, and calcium channel blocking agents may be more appropriate for initial therapy of hypertension in many patients.