Diuretics in the management of hypertension

Clinical pharmacology of antihypertensive drugs

Systemic hypertension is a major public health problem and is perhaps the most common chronic disorder in most societies. Most patients with vascular disease report hypertension in their medical history. Irrespective of the specialty that one practices, every physician will likely encounter patients with systemic hypertension. Unfortunately, an overwhelming number have so-called "primary" or "essential" hypertension for which a cure has yet to be found. Fortunately, excellent therapy is available to control this modern malady. The field of hypertension continues to evolve rapidly, particularly in the field of therapy. During the past two decades, the treatment of hypertension has moved from a cookbook approach to more scientifically based individualized management. This paradigm shift requires the practitioner to acquire sufficient knowledge about individual drugs and how they work in a given patient. Rapid expansion of available drugs has placed a burden on the clinician to keep up with these advances. We hope that the discussions contained herein will ease that burden somewhat and make the treatment options less cumbersome. This article addresses the practical issues related to selection of antihypertensive drugs and provides an overview of advantages and disadvantages of individual drug classes. The reader should also refer to the JNC VI document [1] to further understand the selection of drug therapy based upon compelling indications. The ultimate aim of hypertension management should always be to achieve target or goal blood pressure levels.

Long-term efficacy and safety of terazosin alone and in combination with other antihypertensive agents

This open, multicenter phase III study was designed to assess the efficacy and long-term safety of terazosin (1 to 40 mg/day), alone or in combination with other antihypertensive drugs, in 364 patients with mild to moderate essential hypertension. Compared with baseline values, long-term terazosin monotherapy or combination therapy resulted in consistent decreases in both systolic and diastolic blood pressures, with a mean reduction in supine diastolic pressure of 12 to 14 mm Hg. The numbers of patients with controlled blood pressure at the last evaluable visit of each therapy period were as follows: terazosin alone, 106 of 245 (43%); terazosin with added diuretic, 70 of 112 (63%); diuretic with added terazosin, 47 of 88 (53%); and terazosin plus diuretic with added beta-blocker, 22 of 32 (69%). Most adverse events were mild or moderate in severity. Only pain in extremities had a higher incidence during long-term treatment (6%, 181 to 360-day period) than during initial short-term treatment (5%, 1 to 90-day period). Three of six syncopal events occurred during the initial 180 days of treatment; this 0.8% (3/364) incidence was comparable with that reported previously for short-term studies. Only one case of syncope occurred during terazosin monotherapy. Terazosin was judged to be a safe and effective long-term medication for the treatment of hypertension.

The case for low dose diuretics in hypertension: comparison of low and conventional doses of cyclopenthiazide

In a double blind placebo controlled randomised parallel study the antihypertensive activity and adverse biochemical effects of three doses of cyclopenthiazide were evaluated in patients with mild essential hypertension that had been recently diagnosed or was being treated with a single drug. After a four week placebo washout period 53 patients with diastolic blood pressures between 90-110 mm Hg were randomly assigned to 50, 125, or 500 micrograms cyclopenthiazide or matching placebo for an eight week period of treatment. Blood pressure was measured in the patients' homes by the same observer every two weeks. Serum urea, electrolytes, urate, and creatinine concentrations and 24 hour urinary sodium excretion were monitored every four weeks and serum magnesium concentration and plasma renin activity at the end of the washout and treatment periods. After eight weeks of treatment systolic and diastolic blood pressures were significantly reduced in patients taking 125 and 500 micrograms cyclopenthiazide when compared with those taking placebo. The decrement in serum potassium concentration (0.6 mmol/l) and increase in serum urate concentration 0.06 mmol/l) were greatest with the 500 micrograms dose, the increase in serum urate concentration alone being significant. No change in serum magnesium concentration or 24 hour urinary sodium excretion was noted with any dose of cyclopenthiazide. Only the 500 micrograms dose of cyclopenthiazide significantly increased the mean plasma renin activity (1.8 (95% confidence interval 0.2 to 3.4)-5.4 (3.9 to 6.8) nmol angiotensin I/l/h); the other doses like the placebo had no effect. Cyclopenthiazide 125 micrograms, a dose lower than is currently marketed, produced a similar hypotensive response to 500 micrograms of the drug without upsetting the biochemical profile.

Recent issues in antihypertensive drug therapy

Results of recent large scale treatment trials have demonstrated that aggressive management of high blood pressure prevents progression of mild hypertension to the accelerated or malignant phase and reduces incidence of stroke, congestive heart failure, and left ventricular hypertrophy. These trials mostly have utilized a diuretic-based, stepped-care approach to drug therapy, however, and have not shown a consistent beneficial effect of treatment on coronary heart mortality. In addition, the results of studies such as MRFIT have raised questions about serious risks of diuretic treatment in selected patients. These concerns have led to increased use of nonpharmacologic approaches to lowering blood pressure in patients with mild hypertension, but most patients ultimately require drug therapy. Alternative agents to diuretics now being employed as monotherapy in mild hypertension include beta-blockers, calcium channel blockers, ACE inhibitors, alpha-blockers, alpha- and beta-blockers, and, to a lesser extent, centrally-acting sympatholytics and peripheral adrenergic antagonists. Rational use of these agents primarily is based on a careful evaluation of concomitant medical conditions (see Table 3), as well as their mode of action, relative side effects, ease of administration, and cost. Age and race recently have been found to be important determinants of antihypertensive response to agents such as diuretics, beta-blockers, calcium channel blockers, and ACE inhibitors (see Table 3) and appreciation of these relative differences may affect drug selection. When these factors are taken into account, an effective and well tolerated regimen can be tailored to the individual patient. It is hoped that aggressive treatment of hypertension in the future will cause a further decline in cardiovascular mortality in the United States.

Overall safety of terazosin as an antihypertensive agent

The safety of terazosin, an effective agent for the treatment of hypertension, was assessed by analyzing data from 1,006 hypertensive patients who were enrolled in short-term and/or long-term studies. The total experience with terazosin in this article represents 422.5 patient-years. Changes in pulse rate measurements from pretreatment to posttreatment were not significantly different between the terazosin- and placebo-treated patients (-1.0 beat per minute for the terazosin group and -1.0 beat per minute for the placebo group, in the supine position). Dizziness, headache, and asthenia were the most commonly reported adverse experiences among all terazosin-treated patients, although the incidence of headache in placebo-controlled trials was not significantly different between the terazosin and placebo groups. As a whole, patients receiving terazosin had a tendency to gain small amounts of weight (2 pounds). In addition, there was a trend for slight decreases in hemoglobin, hematocrit, white blood cell count, total protein, and albumin levels in those patients who received terazosin, suggesting hemodilution. Overall, terazosin was shown to be safe in patients with mild to moderate essential hypertension.

Diuretics versus calcium-channel blockers in systemic hypertension: a preliminary multicenter experience with hydrochlorothiazide and sustained-release diltiazem

The safety and efficacy of sustained-release diltiazem 120 to 180 mg, 2 times a day, were compared with hydrochlorothiazide 25 to 50 mg, 2 times a day, and the combination of diltiazem and hydrochlorothiazide in 56 patients with mild to moderate hypertension (supine diastolic blood pressure between 95 and 114 mm Hg) using a placebo-controlled, parallel-design protocol. Data from an additional 21 patients were evaluated for safety only. The data reported herein represent the preliminary experience from a larger 200-patient multicenter study. All patients received placebo for 4 weeks, followed by either hydrochlorothiazide or diltiazem titrated to achieve a diastolic blood pressure reduction of greater than or equal to 10 mm Hg to reach a goal supine diastolic blood pressure of less than 90 mm Hg. Patients not achieving the treatment goal received hydrochlorothiazide plus diltiazem. At week 14, on maintenance monotherapy, diltiazem and hydrochlorothiazide produced comparable reductions in blood pressure from placebo baseline (160.3 +/- 24.3/101.7 +/- 5.5 to 145.2 +/- 24.1/89.8 +/- 7.4 mm Hg with diltiazem, 156.0 +/- 15.6/103.7 +/- 4.7 to 134.1 +/- 12.5/89.2 +/- 9.5 mm Hg with hydrochlorothiazide, p less than 0.001 for both). Diltiazem and hydrochlorothiazide achieved goal blood pressure in 42% and 45% of patients, respectively. The effects in responders were sustained for 6 months. In patients who did not achieve the treatment goal, 63% responded to diltiazem plus hydrochlorothiazide.No clinically significant postural hypotension was observed on any regimen. Heart rate was slightly lower with diltiazem than with hydrochlorothiazide. Adverse effects were minimal with diltiazem, hydrochlorothiazide and diltiazem plus hydrochlorothiazide but more hypokalemia occurred with hydrochlorothiazide.(ABSTRACT TRUNCATED AT 250 WORDS)