Achieving blood pressure goal: initial therapy with valsartan/hydrochlorothiazide combination compared with monotherapy.

The benefits of valsartan (Val)/hydrochlorothiazide (HCTZ) combination as initial treatment for hypertension were evaluated in a post hoc analysis of an 8-week, double-blind, placebo-controlled, parallel-group trial. The highest dose of Val/HCTZ combination (320/25 mg), component monotherapies (Val 320 mg, HCTZ 25 mg) and placebo were selected for this analysis (N=675, 52.1% men, 68.6% Caucasians, mean age 52.9 years, baseline blood pressure (BP) 150.6/99.1 mm Hg). As soon as 2 weeks after initiation of active therapy, greater BP control rates were observed with Val/HCTZ (320/25 mg) compared with Val (320 mg), HCTZ (25 mg) and placebo. Similar results were observed in subgroups of patients with stage 1 and stage 2 hypertension, as well as in diabetic patients. As baseline BP increased, the probability of achieving mean sitting systolic BP (<140 and <130 mm Hg) and mean sitting diastolic BP control (<90 and <80 mm Hg), determined using a logistic regression model, decreased with all treatments. However, at all levels of baseline BP, the probability of achieving BP control was greater with Val/HCTZ combination. The Val/HCTZ combination was well tolerated with overall incidence of adverse events similar to that observed with monotherapy and placebo. These results support the use of Val/HCTZ combination as initial therapy in hypertensive patients unlikely to achieve BP control with a single agent.

Antihypertensive therapy with aliskiren.

Aliskiren represents the first member in a new class of antihypertensive drugs. Inhibiting the renin-angiotensin system at its rate-limiting step is an idea that has been pursued for >30 years; however, earlier compounds failed because of problems related to efficacy, bioavailability, and/or side effects. Aliskiren, a 610 Da nonpeptide molecule, has exceptional affinity for the human renin enzymatic site and a half-life of about 40 h, which make its 3% bioavailability clinically unimportant with continued administration. The drug is not metabolized by CYP P450 enzymes and is excreted >90% unchanged by the fecal route. No adjustments are necessary for renal function, liver function, age, ethnicity, or other prescribed drugs. Blood pressure reductions are similar to those provided by other monotherapies. Interestingly, aliskiren combined with angiotensin receptor blocker or angiotensin-converting enzyme inhibitor therapy leads to a further blood pressure reduction as does combination with a diuretic or calcium channel blocker. The fact that plasma renin activity is reduced to low levels with aliskiren could provide a theoretical advantage over other treatments, while increases in total renin (prorenin) after the drug poses additional food for thought. Studies with primary cardiovascular and renal end points to address these possibilities are in progress.

Comprehensive suppression of the renin-angiotensin-aldosterone system in chronic kidney disease: covering all of the bases.

Reducing proteinuria and blood pressure in chronic kidney disease (CKD) decreases rate of progression. Inhibition of the renin-angiotensin system by angiotensin-converting enzyme inhibitors and/or angiotensin receptor blockers is beneficial in reducing proteinuria but incomplete in suppressing aldosterone production and its renal effects. Adding aldosterone receptor blockers to these other agents may further halt the progression of CKD.

Salt sensitivity, pulse pressure, and death in normal and hypertensive humans.

Although factors such as age, blood pressure, and its responsiveness to changes in sodium balance and extracellular fluid volume status (salt sensitivity) are associated with an increased risk of end-organ disease and cardiovascular events in hypertensive subjects, no such relationship with mortality has been demonstrated for salt sensitivity in normotensive subjects. We conducted long-term follow-up of 430 normal and 278 hypertensive subjects in whom assessment of salt sensitivity of blood pressure was performed as long as 27 years ago. We ascertained the status of 596 subjects (85% of the total population), 123 (21%) of whom had died. The following initial measurements were significantly (P<0.002) associated with subjects who had died compared with subjects known to be alive: age at study, pulse pressure, systolic, diastolic, and mean arterial pressures, hypertension, salt sensitivity, baseline renin levels, and body mass index (but not body weight). A stepwise logistic regression found the following independent predictors of death (odds ratio, 95% CI): age at initial study (1.08, 1.06 to 1.10), baseline blood pressure (1.03, 1.01 to 1.04), sodium sensitivity (1.73, 1.02 to 2.94), and male gender (1.91, 1.15 to 3.17). When survival curves were examined, normotensive salt-sensitive subjects aged >25 years when initially studied were found to have a cumulative mortality similar to that of hypertensive subjects, whereas salt-resistant normotensive subjects had increased survival (P:<0.001). These observations provide unique evidence of a relationship between salt sensitivity and mortality that is independent of elevated blood pressure.

Effects of isradipine or enalapril on blood pressure in salt-sensitive hypertensives during low and high dietary salt intake. MIST II Trial Investigators.

This large multicenter study, tested the antihypertensive effects of isradipine, a dihydropyridine calcium channel blocker and enalapril, an angiotensin-converting enzyme inhibitor, in salt-sensitive hypertensive patients under low and high salt intake diets. After a 3-week (weeks -9 to -6) of ad lib salt diet, those patients who had a sitting diastolic blood pressure (SDBP) of > or =95 but < or =115 mm Hg qualified to enter a 3-week (weeks -6 to -3) placebo run-in low salt diet (50 to 80 mmol Na+/day). Then high salt (200 to 250 mmol Na+/day) was added to the placebo treatment for 3 weeks (weeks -3 to 0). Those patients who demonstrated an increase in SDBP > or =5 mm Hg from the low to high salt diet were considered salt sensitive and were randomized into a 4-week (weeks 0 to 4) double-blind treatment period of either isradipine 2.5 to 10 mg twice a day, enalapril 2.5 to 20 mg twice a day, or placebo. Then they entered a 3-week (weeks 4 to 7) placebo washout phase of low salt diet (50 to 80 mmol Na+/day). After week 7 and while the low salt diet was continued the patients were restarted on their double-blind treatment for 4 more weeks (weeks 7 to 11) and the study was completed. Of 1,916 patients screened, 464 were randomized into the double-blind treatment phase and 397 completed the study. Both isradipine and enalapril decreased the sitting systolic blood pressure (SSBP) and SDBP during the high salt diet, to a similar degree, whereas enalapril caused a greater reduction in SSBP and SDBP than isradipine during the low salt diet (11.3 +/- 1.2/7.7 +/- 0.7 mm Hg v 7.7 +/- 0.9/4.8 +/- 0.6 mm Hg, mean +/- SEM, respectively, P < .02). Within drugs, the effect of isradipine on blood pressure (BP) was higher during the high than the low salt diet (14.9 +/- 1.5 v 7.6 +/- 1.3 mm Hg for SSBP and 10.1 +/- 0.6 v 4.8 +/- 0.9 mm Hg for SDBP, P < .001), but enalapril exerted a similar effect during both diets. Because salt restriction lowered both SSBP and SDBP, the lowest BP achieved with both drugs were during the salt restriction phase.

Doxazosin in elderly patients with hypertension.

Hypertension constitutes a major cardiovascular risk factor of high prevalence in the elderly, and reducing elevated blood pressure has been shown to be of significant benefit in decreasing the incidence of cardiovascular and cerebrovascular disease in this patient population. Elderly patients are more likely to have comorbid disorders, such as dyslipidaemia, diabetes, renal disease, atherosclerosis and, for males, benign prostatic hyperplasia (BPH). Therefore, when choosing an antihypertensive agent for elderly patients, it is particularly important to ensure that treatment does not exacerbate comorbid conditions and does not interact deleteriously with any concurrent medication that the patient is taking. The alpha 1-adrenoceptor antagonist, doxazosin, has been shown to be an effective, well-tolerated antihypertensive therapy in elderly male patients and does not exacerbate--and in some cases improves--some other common disorders. Doxazosin has been shown to be effective in reducing the symptoms of BPH in elderly patients whose blood pressure is well controlled by concomitant antihypertensive medication. In addition, improvements in the symptoms of BPH as well as reductions in blood pressure have been observed in elderly men with mild-to-moderate hypertension. Doxazosin has been shown to have positive effects on lipid profiles and glycaemic control, which make it an attractive choice of therapy for elderly patients with hypertension and diabetes or dyslipidaemia. In addition, doxazosin is administered once daily, either in the morning or the evening, which may aid compliance, an important consideration in the elderly.

Salt and blood pressure.

A substantial amount of new information concerning salt-sensitivity of blood pressure in humans has appeared in the recent past. This review discusses recent studies examining two techniques used for the assessment of salt sensitivity as well as several studies attempting to identify specific genetic factors associated with variations in the blood pressure responses to alterations in sodium and extracellular fluid volume. New observations related to the demographics, physiology, and mechanisms for these varied responses are also presented.

Obesity, blood pressure, and renal sodium handling.

A substantial body of work has been recently directed toward elucidation of the relationships between body weight, blood pressure, and renal and vascular function. In this review only a few of the myriad studies are highlighted in order to survey areas of current investigation and controversy. Epidemiologic studies have confirmed the blood pressure-body weight relationship but suggest a link to insulin resistance. The majority of investigative work in the mechanism and abnormalities in obesity and their link to blood pressure have focused on the kidney as the primary organ of interest. In addition to alterations in renal blood flow and function, the sympathetic nervous system has also been implicated. The role of the major adrenal steroid dehydroepiandrosterone (DHEA) has been examined, as have the roles of bradykinin and leptin, the exiting new polypeptide thought to play a role in obesity.

Influence of race and dietary salt on the antihypertensive efficacy of an angiotensin-converting enzyme inhibitor or a calcium channel antagonist in salt-sensitive hypertensives.

Dietary salt restriction is a recommended adjunct with antihypertensive therapy. There may be racial differences in blood pressure response to salt restriction while on antihypertensive therapy. We performed a multicenter, randomized, double-blind, placebo-controlled, parallel-group clinical trial (black, n=96; Hispanic, n=63; white, n=232). Participants were initially preselected for stage I to III hypertension and then further selected for salt sensitivity (> or = 5 mm Hg increase in diastolic blood pressure after 3 weeks of low salt [< or = 88 mmol/d Na+] and high salt [>190 mmol/d Na+] diet). We compared the antihypertensive effect of an angiotensin-converting enzyme inhibitor (enalapril 5 or 20 mg BID) or a calcium channel antagonist (isradipine 5 or 10 mg BID) during alternating periods of high and low salt intake. The main outcome measure was blood pressure change and absolute blood pressure level achieved with therapy. During the high salt diet (314.7+/-107.5 mmol/d urinary Na+) there was greater downward change in blood pressure with both enalapril and isradipine compared with the low salt diet (90.1+/-50.8 mmol/d Na+); however, the absolute blood pressure achieved in all races was consistently lower on a low salt diet for both agents. Black, white, and Hispanic isradipine-treated salt-sensitive hypertensives demonstrated a smaller difference between high and low salt diets (black, -3.6/-1.6 mmHg; white, -6.2/-3.9 mmHg; Hispanic, -8.1/-5.3 mm Hg) than did enalapril-treated patients (black, -9.0/-5.3 mm Hg; white, -11.8/-7.0 mm Hg; Hispanic, -11.1/-5.6 mm Hg). On the low salt diet, blacks, whites, and Hispanics had similar blood pressure control with enalapril and isradipine. On the high salt diet, blacks had better blood pressure control with isradipine than with enalapril, whereas there was no difference in the blood pressure control in whites and Hispanics treated with either drug. Dietary salt reduction helps reduce blood pressure in salt-sensitive hypertensive blacks, whites, and Hispanics treated with enalapril or isradipine. These data demonstrate that controlling for salt sensitivity diminishes race-related differences in antihypertensive activity.

There are no racial, age, sex, or weight differences in the effect of salt on blood pressure in salt-sensitive hypertensive patients.

BACKGROUND: This report is part of a larger, multicenter, placebo-controlled study designed to test the effects of low and high salt intake on the antihypertensive action of enalapril maleate or isradipine in salt-sensitive, hypertensive patients. OBJECTIVE: To present our findings with respect to the effects of race, age, sex, and weight on the blood pressure response to low and high salt intake in salt-sensitive hypertensive patients before randomization into the larger study. PATIENTS AND METHODS: After 3 week (weeks -9 to -6) of ad lib salt intake (100-200 mmol/d of sodium), 1916 patients whose sitting diastolic blood pressure was between 95 and 115 mm Hg entered a 3-week period (week -6 to -3) of low salt intake (50-80 mmol/d of sodium) and then a 3-week period (week -3 to 0) of high salt intake (200-250 mmol/d of sodium). Of the 1916 patients, 624 were identified as being sensitive to salt by demonstrating an increase in sitting diastolic blood pressure of equal to or more than 5 mm Hg from the low to high salt intake. Of these patients, 367 were white, 156 were black, 92 were Hispanic, 8 were Asian, and 1 was American Indian. Also, 315 were men and 309, women; 351 were 55 years or younger and 273 were older than 55 years; and 195 had a body mass index of 27 or less and 429 had a body mass index higher than 27. RESULTS: The sitting blood pressure decreased with salt restriction and increased with salt load in all groups of patients (P < .001). There were no statistically significant differences in the blood pressure changes to salt changes by race, age, sex, and weight. CONCLUSIONS: This large, multicenter study did not demonstrate any statistically significant effect of race, age, sex, and weight on blood pressure response to salt changes in salt-sensitive hypertensive patients.

Heterogeneous responses to changes in dietary salt intake: the salt-sensitivity paradigm.

Blood pressure responses to increases and decreases in dietary salt intake are heterogeneous. In some hypertensive individuals, decreases in blood pressure with salt restriction are clinically significant and approach that achieved with medication. In others, little or no change in blood pressure occurs, whereas in still others, blood pressure may actually increase with salt restriction. The heterogeneous responses are partly acquired and involve the influences of age, the intake of other electrolytes, and the influence of certain medications. Genetic predisposition may also play a substantial role because salt sensitivity is increased in black individuals and in persons with non-insulin-dependent diabetes mellitus. Some uncommon but readily diagnosed salt-sensitive genetic syndromes, such as glucocorticoid-remediable aldosteronism and Liddle syndrome, have been identified. Short-term volume expansion and contraction and longer-term dietary interventions appear to be reproducible and may be used to identify salt-sensitive and salt-resistant individuals; however, these maneuvers are cumbersome and cannot be used on a large scale. Molecular genetic techniques for identifying individuals with salt-sensitive and salt-resistant essential hypertension are not yet available, but if the putative gene polymorphisms are identified, such techniques may replace the current trial-and-error methods.

Compliance to a low-salt diet.

Community intervention projects, efforts at single centers, and multicenter, prospective, dietary salt-restriction trials suggest that such an intervention is neither easy to achieve nor simple to maintain. Community-wide interventions based on advertisements, pamphlets, posters, radio messages, instructions in schools or other institutions, and cooperation from food suppliers such as butchers and bakers resulted in a slight decrease in salt consumption, mostly in normotensive women. A demonstration project at a single center showed that lowering salt intake long-term by 50% in hypertensive patients was feasible. That study included self-administered, positive-feedback devices to indicate adherence and a role for a household partner in achieving compliance. Multicenter intervention trials also indicate that reducing salt intake in the long term is feasible. However, in all intervention trials the subjects were highly selected, stable, generally married male volunteers. An elaborate training program involving many health care professionals was necessary and recidivism was common. Successful intervention requires specific goals and delegated responsibilities on the part of the health care team, careful assessment of the patient and the risk factors, as well as motivation for behavioral change, a specific plan for implementation, repetitive educational efforts, and a built-in monitoring mechanism.

Hemodynamic, renal, and hormonal responses to lower body positive pressure in human subjects.

Studies in healthy human subjects subjected to lower body positive pressure (LBPP) have failed to elucidate many of the physiologic effects of this maneuver. In 7 healthy, well-hydrated men we studied the following responses to LBPP (35 mm Hg, 1 hour, supine position): systemic and renal hemodynamics; urine volume (UV), urine osmolality (Uosm), and urine sodium level (UNaV); free water (CH20) and osmolar (Cosm) clearances; plasma renin activity (PRA); levels of aldosterone (PA), cortisol (CORT), norepinephrine (NE), atrial natriuretic peptide (ANP), and vasopressin (AVP); osmolality (Posm); and serum sodium level. Subjects were restudied on a control day with zero trouser pressure. The recorded changes (p < 0.05) when comparing the LBPP day with the control day were as follows: fractional Na+ reabsorption increased (98.7% +/- 0.2% to 99.3% +/- 0.1%) and UNaV decreased (0.19 +/- 0.03 mEq/min to 0.10 +/- 0.01 mEq/min), with concomitant increases in PRA (1.7 +/- 0.2 ng/ml/90 min to 4.5 +/- 1.8 ng/ml/90 min), PA (7.7 +/- 0.7 ng/dl to 9.3 +/- 1.5 ng/dl), and CORT (13.0 +/- 2.6 mg/dl to 19.2 +/- 3 mg/dl); the increase in blood pressure with LBPP (96 +/- 3 mm Hg to 112 +/- 4 mm Hg) was greater than that during control conditions. Renal plasma flow tended to display an interactive pattern across days, with a slight decline during LBPP (5%) and a slight elevation under control conditions (9%). On the LBPP day only, filtered Na+ declined (15 +/- I mEq/min to 12 +/- 1 mEq/min) as a function of reduced glomerular filtration rate (112 +/- 5 ml/min to 91 +/- 7 ml/min), blood volume decreased (by 2.7% +/- 0.7%), CO decreased (5.5 +/- 0.3 L/min to 4.7 +/- 0.3 L/min), and stroke volume declined (101 +/- 6 ml to 84 +/- 3 ml). On both days, NE increased (control, 221 +/- 23 pg/ml to 340 +/- 33 pg/ml; LBPP, 236 +/- 17 pg/ml to 369 +/- 31 pg/ml) and ANP increased (control, 47 +/- 7 pg/ml to 97 +/- 21 pg/ml; LBPP, 49 +/- 10 pg/ml to 104 +/- 30 pg/ml). We concluded that LBPP reduces renal sodium excretion. The mechanism for this reduction is not known, although it did occur in association with an increase in plasma renin activity, which in turn results from mechanical reduction of renal perfusion, stress-related CORT stimulation, a reflex-based elevation in peripheral vascular resistance leading to a reflex increase in plasma renin activity, or a combination of these.

Salt sensitivity: does it play an important role in the pathogenesis and treatment of hypertension?

Abundant data confirm a role for sodium intake in human blood pressure and for the pathogenesis and treatment of some forms of hypertension. New information concerning mechanisms for the effect of salt on blood pressure, as well as the relationship between salt intake and the heart and kidneys, is reviewed.