Clinical experience with the angiotensin II receptor antagonist losartan. A preliminary report

Design, synthesis and biological evaluation of renin inhibitors guided by simulated annealing of chemical potential simulations

We have applied simulated annealing of chemical potential (SACP) to a diverse set of ∼150 very small molecules to provide insights into new interactions in the binding pocket of human renin, a historically difficult target for which to find low molecular weight (MW) inhibitors with good bioavailability. In one of its many uses in drug discovery, SACP provides an efficient, thermodynamically principled method of ranking chemotype replacements for scaffold hopping and manipulating physicochemical characteristics for drug development. We introduce the use of Constrained Fragment Analysis (CFA) to construct and analyze ligands composed of linking those fragments with predicted high affinity. This technique addresses the issue of effectively linking fragments together and provides a predictive mechanism to rank order prospective inhibitors for synthesis. The application of these techniques to the identification of novel inhibitors of human renin is described. Synthesis of a limited set of designed compounds provided potent, low MW analogs (IC₅₀s<100nM) with good oral bioavailability (F>20-58%).

Synthesis and pharmacological evaluation of a novel AT1 angiotensin II receptor antagonist with anti-hypertension and anti-tumor effects

A new compound 2-(4-((2-butyl-5-nitro-1H-benzo[d]imidazol-1-yl)methyl)-1H-indol-1-yl) benzamide (1) was designed, synthesized and evaluated as a novel AT1 receptor antagonist. Compound 1 displayed high affinity to AT1 receptor with an IC50 value of 1.65 ± 0.2 nM in radio-ligand binding assays. It had an efficient and long-lasting effect in reducing blood pressure which could last for more than 12 h at the dose of 10 mg/kg in spontaneously hypertensive rats. Acute toxicity tests suggested that compound 1 was safe with the LD50 value of 2519.81 mg/kg. Besides, in vitro and in vivo tests suggested its anti-proliferative and anti-tumor activities, respectively. So compound 1 could be considered as a novel anti-hypertension, anti-tumor candidate and deserved further investigation.

Lead optimization of 5-amino-6-(2,2-dimethyl-5-oxo-4-phenylpiperazin-1-yl)-4-hydroxyhexanamides to reduce a cardiac safety issue: discovery of DS-8108b, an orally active renin inhibitor

With the aim to address an undesired cardiac issue observed with our related compound in the recently disclosed novel series of renin inhibitors, further chemical modifications of this series were performed. Extensive structure-activity relationships studies as well as in vivo cardiac studies using the electrophysiology rat model led to the discovery of clinical candidate trans-adamantan-1-ol analogue 56 (DS-8108b) as a potent renin inhibitor with reduced potential cardiac risk. Oral administration of single doses of 3 and 10 mg/kg of 56 in cynomolgus monkeys pre-treated with furosemide led to significant reduction of mean arterial blood pressure for more than 12 h.

Discovery of DS-8108b, a Novel Orally Bioavailable Renin Inhibitor

A novel orally bioavailable renin inhibitor, DS-8108b (5), showing potent renin inhibitory activity and excellent in vivo efficacy is described. We report herein the synthesis and pharmacological effects of 5 including renin inhibitory activity in vitro, suppressive effects of ex vivo plasma renin activity (PRA) in cynomolgus monkey, pharmacokinetic data, and blood pressure-lowering effects in an animal model. Compound 5 demonstrated inhibitory activities toward human renin (IC50 = 0.9 nM) and human and monkey PRA (IC50 = 1.9 and 6.3 nM, respectively). Oral administration of single doses of 3 and 10 mg/kg of 5 in cynomolgus monkey on pretreatment with furosemide led to dose-dependent significant reductions in ex vivo PRA and sustained lowering of mean arterial blood pressure for more than 12 h.

Prolonged Refractory Hypotension following Combined Amlodipine and Losartan Ingestion Responsive to Metaraminol

Introduction. Overdose with the calcium channel blocker amlodipine can cause profound hypotension that may be exacerbated by the concurrent ingestion of an angiotensin II receptor antagonist. Best management of such overdoses is uncertain although the use of hyperinsulinaemia-euglycaemia (HIE) has been recommended. Case report. We report a case of mixed amlodipine and losartan overdose in a 50-year-old lady. Severe hypotension was resistant to conventional vasopressors and high-dose insulin/euglycaemia, but did respond to a metaraminol infusion. Conclusion. A trial of metaraminol early in severe cases of calcium channel blocker and angiotensin II receptor antagonist toxicity may be of benefit, especially when conventional ionotropic treatment measures are failing.

Angiotensin II Type-2 receptors modulate inflammation through signal transducer and activator of transcription proteins 3 phosphorylation and TNFα production

Angiotensin subtype-1 receptor (AT(1)R) influences inflammatory processes through enhancing signal transducer and activator of transcription proteins 3 (STAT3) signal transduction, resulting in increased tumor necrosis factor-α (TNF-α) production. Although angiotensin subtype-2 receptor (AT(2)R), in general, antagonizes AT(1)R-stimulated activity, it is not known if AT(2)R has any anti-inflammatory effects. In this study, we tested the hypothesis that AT(2)R activation plays an anti-inflammatory role by reducing STAT3 phosphorylation and TNF-α production. Changes in AT(2)R expression, TNF-α production, and STAT3 phosphorylation were quantified by Western blotting, Bio-Plex cytokine, and phosphoprotein cellular signaling assays in PC12W cells that express AT(2)R but not AT(1)R, in response to the AT(2)R agonist, CGP-42112 (CGP, 100 nm), or AT(2)R antagonist PD-123319 (PD, 1 μm). A 100% increase in AT(2)R expression in response to stimulation with its agonist CGP was observed. Further, AT(2)R activation reduced TNF-α production by 39% and STAT3 phosphorylation by 83%. In contrast, PD decreased AT(2)R expression by 76%, increased TNF-α production by 84%, and increased STAT3 phosphorylation by 67%. These findings suggest that increased AT(2)R expression may play a role in the observed decrease in inflammatory pathway activation through decreased TNF-α production and STAT3 signaling. Restoration of AT(2)R expression and/or its activation constitute a potentially novel therapeutic target for the management of inflammatory processes.

The frail renin-angiotensin system

Over the last few decades, the understanding of the renin-angiotensin system (RAS) has advanced dramatically. RAS is now thought to play a crucial role in physiologic and pathophysiologic mechanisms in almost every organ system and is a key regulator of hypertension, cardiovascular disease, and renal function. Angiotensin II (Ang II) promotes inflammation and the generation of reactive oxygen species and governs onset and progression of vascular senescence, which are all associated with functional and structural changes, contributing to age-related diseases. Although the vast majority of the actions of Ang II, including vascular senescence, are mediated by the Ang II type 1 receptor (AT1R), the identification, characterization, and cloning of the angiotensin type 2 receptor has focused attention on this receptor and to its antagonistic effect on the detrimental effects of AT1R. This review provides an overview of the changes in RAS with aging and age-disease interactions culminating in the development of frailty.

Design and optimization of a substituted amino propanamide series of renin inhibitors for the treatment of hypertension

The discovery and SAR of a new series of substituted amino propanamide renin inhibitors are herein described. This work has led to the preparation of compounds with in vitro and in vivo profiles suitable for further development. Specifically, challenges pertaining to oral bioavailability, covalent binding and time-dependent CYP 3A4 inhibition were overcome thereby culminating in the identification of compound 50 as an optimized renin inhibitor with good efficacy in the hypertensive double-transgenic rat model.

Comparative effects of chronic ACE inhibition and AT1 receptor blocked losartan on cardiac hypertrophy and renal function in hypertensive patients

The present study describes the effects of losartan and the angiotensin-converting enzyme inhibitor enalapril on blood pressure, echocardiographically calculated left ventricular mass, renal function evaluated by glomerular filtration rate and quality of life. The renin-angiotensin-aldosterone system is of importance for cardiovascular growth. There is substantial experimental documentation in animals that the angiotensin II antagonist, losartan, decreases the cardiac hypertrophy response caused by elevated arterial pressure as well as intravascular volume overload. However, data in humans is scarce. This is a 3-year, randomised, double-blind study with parallel group design in 50 patients with essential hypertension. The results show that both drugs reduced blood pressure equally effectively, and also left ventricular mass (P < 0.001). After 3 years of treatment glomerular filtration rate significantly increased with losartan (P < 0.005). Serum uric acid fell modestly although significantly, dose-dependent in losartan patients compared with an increase in enalapril patients. A fall in serum potassium from the pre-study period was observed in all patients. There was no difference between treatments in terms of patient satisfaction on quality of life. Both drugs have relatively similar hormonal and haemodynamic effect, with an excellent tolerability profile; they appear to induce comparable blood pressure falls in hypertensive patients in particular, therapy based on specific Ang II blockade may offer advantages in high risk hypertensives if left ventricular hypertrophy is present. Both enalapril and losartan, in improving the renal function attenuating the intrarenal effects of angiotensin II, might be able to reverse the pathophysiology of essential hypertensive kidney disease, and should be first-choice drugs in the treatment of essential hypertension.

Valsartan and the kidney: review of preclinical and clinical data

In both diabetic and nondiabetic renal disease, reducing blood pressure with antihypertensive therapy has beneficial effects on renal function. The key role of the renin-angiotensin system in blood pressure and volume homeostasis has long been established, but its importance for the overall normal functioning of the kidney itself is also increasingly being recognized. Angiotensin-converting enzyme (ACE) inhibitors, widely and successfully used in the treatment of hypertension, may also provide renal protection independent of blood pressure reduction; however, their relatively nonspecific mode of action in blocking an early metabolic step entails major clinical disadvantages, such as accumulation of bradykinin and substance P, that may cause the characteristic ACE-inhibitor side effects of persistent dry cough and, more rarely, angioneurotic edema. Angiotensin II antagonists or receptor blockers, a new class of antihypertensive agent, selectively antagonize the AT1 receptor subtype and, because of greater specificity, do not give rise to the side effects associated with ACE inhibitors. More important, these new drugs may have mechanistic advantages over other antihypertensives, including ACE inhibitors.

Irbesartan, an angiotensin type 1 receptor inhibitor, regulates markers of inflammation in patients with premature atherosclerosis

OBJECTIVES

This study assessed the role of angiotensin II type 1 (AT1) receptor antagonists on inflammatory mechanisms involved in atherogenesis. Specific inflammatory markers included solubilized tumor necrosis factor-alpha receptor II (sTNF-alphaRII), vascular cell adhesion molecule-1 (VCAM-1) and superoxide. In addition, the AT1 receptor blocker irbesartan was evaluated for its ability to suppress these markers in individuals with atherosclerosis.

BACKGROUND

Mechanisms involved in the complex process of atherogenesis include alterations in the inflammatory responses. The use of compounds that suppress these responses may reduce the degree of damage seen in atherosclerosis.

METHODS

With a cross-sectional study design, 33 normotensive patients with stable coronary artery disease (CAD) were treated with irbesartan for a 24-week period. These patients were compared against a control population with no known coronary atherosclerosis. Marker levels were measured by enzyme-linked immunosorbent assay technique and lucigenin chemiluminescence assay and statistically evaluated by two-way repeated measures analysis of variance.

RESULTS

All patients with coronary artery disease had increased levels of inflammatory molecules over those of control patients. Treatment with irbesartan in these patients significantly reduced levels of inflammatory molecules measured. Soluble VCAM-1 levels were reduced by 36%; soluble TNF-alpha levels were reduced by 54% and superoxide level decreased by 52%. Maximal suppression of inflammatory markers by irbesartan therapy in patients with CAD was seen at 12 weeks.

CONCLUSIONS

The effect of irbesartan on each inflammatory marker is significant. Our results show that use of irbesartan may retard the inflammatory process seen in premature forms of atherosclerosis.

The future of obesity research

As endocrinologists, we view better treatment as the goal of obesity research. The ideal obesity treatment would reduce body fat substantially, with preferential loss from the visceral compartment, and preserve lean tissue with a minimum of side effects. Obesity has been recognized as a chronic disease since 1985. Chronic diseases recognized before obesity may predict the future of obesity research. Initial treatments of chronic diseases commonly arise from empirical observations. These observations often stimulate basic research into the physiologic mechanisms responsible. Such cross-fertilization between the clinic and basic science is desirable and expected. As more is learned about the physiology of obesity, treatments can be expected to use more downstream mechanisms with less unwanted side effects, the reliance on surgical treatments can be expected to decline, and molecular approaches are likely to play an increasingly important role. With a better physiologic understanding of obesity, advanced clinical endpoints will become more important and molecular approaches are likely to play a more important role in discovery and treatment. Due to the availability of molecular approaches, obesity treatment is expected to advance faster than chronic disease research of the past.

A pharmacokinetic and pharmacodynamic study of the potential drug interaction between tasosartan and atenolol in patients with stage 1 and 2 essential hypertension

The primary objective of this study was to evaluate the pharmacokinetics (PK) and pharmacodynamics (PD) of tasosartan and atenolol administered alone and concomitantly under steady-state conditions in 17 patients ages 18 to 65 years diagnosed with stage 1 to 2 essential hypertension. After a 3- to 14-day qualification period, all patients received placebo tasosartan on days--1 through 5 and 25 through 34, atenolol alone (50 mg) on days 1 through 5, atenolol (50 mg) + tasosartan (50 mg) on days 6 through 19, and tasosartan (50 mg) alone on days 20 through 24. A PK and PD evaluation of atenolol alone was performed on study day 5. On study day 19, PK and PD of both tasosartan and atenolol were assessed. PK and PD evaluation for tasosartan alone was assessed on study day 24. The coadministration of atenolol + tasosartan did not affect the pharmacokinetics of tasosartan, its major metabolite (enoltasosartan), or atenolol when compared with tasosartan or atenolol administered separately. For area under the change in diastolic blood pressure curve, the reduction was significantly greater after tasosartan + atenolol compared with that after atenolol alone (336 +/- 85 and 190 +/- 71 mmHg.24 h; p < 0.05 for combination and atenolol alone, respectively; mean +/- SEM). Combination therapy also caused a maximal reduction in diastolic blood pressure that is significantly more than with monotherapy with atenolol (-27 +/- 2 mmHg and -20 +/- 2 mmHg, respectively, p < 0.05). The additive effects of tasosartan and atenolol in decreasing diastolic blood pressure may provide a rationale for combination antihypertensive therapy.

Pharmacologic, pharmacokinetic, and therapeutic differences among angiotensin II receptor antagonists

Over the past 4 years, six angiotensin II receptor antagonists (ARBs) were approved for treating essential hypertension. They differ with respect to dosing, metabolism, elimination, clinical efficacy, and investigational applications. Candesartan cilexetil is the only prodrug among the agents. Losartan is distinguished from other ARBs by cytochrome P450 (CYP) 3A4- and CYP2C9-mediated biotransformation to its active metabolite EXP-3174. No ARB requires dosage adjustment for renal impairment, but the initial dose of losartan should be reduced 50% in hepatically impaired patients. None of the drugs is significantly cleared by hemodialysis. Completion of continuing trials will elucidate the drugs' role in treating heart failure, cerebral stroke, and myocardial infarction.

Non-peptide angiotensin type 1 receptor antagonists in the treatment of hypertension

Angiotensin II (Ang II) acts at the cellular level on two receptor subtypes: the AT1 receptor which can be blocked by losartan and its analogues (the 'sartan family'), and the AT2 receptor that does not react with the above antagonists but which can be blocked by different compounds, such as PD123319. AT1 receptor blockade has proven to be a highly effective means of interference with the renin-angiotensin system (RAS) and hence of reducing high blood pressure. As a result of the terminal blockade of the RAS cascade, circulating Ang II levels tend to rise two- to threefold. The free access of such enhanced levels to uninhibited AT2 receptors may be clinically relevant, as argued in the present review. The most extensive experimental and clinical experience with AT1 receptor blockade so far has been obtained with the pioneer drug losartan, although major contributions have also been made on candesartan cilexetil, irbesartan and valsartan. All of these four drugs have been instrumental in substantial clinical trials, serving as sources of information in the clinically oriented part of this review. AT1 receptor blocking drugs generally provide a relatively gradual decrease in blood pressure, which is comparable to that obtained with conventional anti-hypertensive drugs. Clinical trials reveal an astounding lack of drug-related adverse effects, scoring even better than placebo in terms of frequencies and sometimes patterns. The trough/peak ratio on single dosages seems to have been mastered, particularly with the second generation of AT1 receptor blockers, as is evident from 24 h ambulatory blood pressure monitoring. Combination with low-dose thiazide regimens is well established. Intermediate endpoints (micro-albuminuria and left ventricular hypertrophy) appear to be controllable. Morbid cardiovascular sequelae are currently under study in comparison with beta- and calcium channel blockade.

Substituted piperidines--highly potent renin inhibitors due to induced fit adaptation of the active site

The identification, synthesis and activity of a novel class of piperidine renin inhibitors is presented. The most active compounds show activities in the picomolar range and are among the most potent renin inhibitors ever identified.

Bradykinin-dependent cardioprotective effects of losartan against ischemia and reperfusion in rat hearts

It is unclear whether losartan, an angiotensin II type 1 (AT1) receptor antagonist, protects the heart against acute ischemia-reperfusion injury. Therefore we evaluated cardiac protection conferred by pre- and postischemic treatment as well as by exclusive postischemic treatment with losartan. Furthermore, we sought to determine both the extent of this protection and its dependence on bradykinin in comparison with quinaprilat, a cardioprotective angiotensin-converting enzyme inhibitor. Cardiac protection was assessed as recovery of coronary flow, left ventricular developed pressure, phosphocreatine, and adenosine triphosphate (ATP) in isolated perfused rat hearts after 15 min of global ischemia and 30 min of postischemic reperfusion. We found that, in hearts pre- and postischemically treated with losartan (1 microM) or quinaprilat (0.1 microM), these variables all recovered significantly better than those in untreated control hearts. In hearts that were only postischemically treated with losartan, these variables also recovered significantly better than those in control hearts. In contrast, in hearts treated with the combination of the bradykinin B2 receptor antagonist Hoe 140 with quinaprilat or losartan, the recovery of the variables no longer differed from that in control hearts. In conclusion, losartan protects the heart against acute ischemia-reperfusion injury. This protection can be achieved by pre- and postischemic treatment as well as by exclusive postischemic treatment with losartan. Furthermore, the extent of this protection is equivalent to that conferred by quinaprilat and, unexpectedly, dependent on bradykinin.

ACE inhibition but not angiotensin II antagonism reduces plasma fibrinogen and insulin resistance in overweight hypertensive patients

The aim of this study was to compare the effects of the angiotensin-converting enzyme (ACE) inhibitor perindopril and the angiotensin II antagonist losartan on insulin sensitivity and plasma fibrinogen in overweight hypertensive patients. Twenty-eight overweight mild to moderate [diastolic blood pressure (DBP) >90 and <110 mm Hg] hypertensives aged 43-64 years, after a 4-week placebo period, were randomized to perindopril, 4 mg o.d., or losartan, 50 mg o.d., for 6 weeks. Then, after a new placebo period, patients were crossed to the alternative regimen for further 6 weeks. At the end of the placebo and of the treatment periods, blood pressure was measured, plasma fibrinogen was evaluated, and insulin sensitivity was assessed by the euglycemic, hyperinsulinemic clamp technique. Glucose infusion rate (GIR) during the last 30 min of clamp and total glucose requirement (TGR) were evaluated. Both perindopril and losartan reduced SBP (by a mean of 20.2 mm Hg, p < 0.001 vs. placebo; and 15.8 mm Hg, p = 0.002 vs. placebo, respectively) and DBP (by a mean of 15.2 mm Hg, p = 0.001 vs. placebo, and 11.8 mm Hg, p = 0.01 vs. placebo respectively), with no difference between the two treatments. GIR was significantly increased by perindopril (+2.91 mg/min/kg, p = 0.042 vs. placebo), but not by losartan (+0.28 mg/min/kg, NS). TGR was not modified by losartan but was increased by perindopril (+9.3 g, p = 0.042 vs. placebo). Plasma fibrinogen levels were reduced by perindopril (-53.4 mg/dl, p = 0.022 vs. placebo) but not by losartan (-16.8 mg/dl, NS). The perindopril-induced decrease in fibrinogen was correlated with the increase in GIR (r = 0.39; p < 0.01). These findings suggest that fibrinogen decrease produced by the ACE inhibitor is related to its action on insulin sensitivity, which seems to be dependent not on angiotensin II blockade but rather on other mechanisms.

Pathologic consequences of increased angiotensin II activity

Advances in molecular medicine and pharmacology have allowed clinicians to critically reassess the renin-angiotensin system. Angiotensin II (AII) participates in the control of cardiovascular function and electrolyte balance, and plays a part in the regulation of cellular oncogenes and the expression of growth factors. The expression of the proteins of the renin-angiotensin system in organs other than the kidneys suggests that these diverse actions are associated with the peptide in the local environment. Tissue renin-angiotensin activity has prompted the investigation of alternate pathways for the production of AII and characterization of novel forms of angiotensin peptides that counteract the vasoconstrictor and proliferative actions of AII. The heptapeptide angiotensin-(1-7) appears to be critically involved in regulating the angiotensinogen activity of AII through stimulation of vasodilator prostaglandins and release of nitric oxide. Study in this area has been accelerated by the identification of receptors that convey the actions of angiotensin peptides at the cellular level and the pharmacologic characterization of agents that inhibit the ability of AII to bind to target receptors. The introduction of a new class of orally active AII-receptor blockers has provided a specific test of the role of AII in the development of essential hypertension and the potential for improved therapy for hypertension and cardiac and vascular sequelae.

Angiotensin II receptors involved in the enhancement of noradrenergic transmission in the caudal artery of the spontaneously hypertensive rat

1. The effects of the AT1 receptor antagonist losartan and the AT2 receptor antagonist PD 123319, on actions of angiotensin II in isolated caudal arteries of spontaneously hypertensive (SH) and age-matched normotensive (Wistar-Kyoto) rats were compared. 2. Angiotensin II (0.1-3 microM) produced concentration-dependent increases in perfusion pressure in artery preparations from both SH and Wistar-Kyoto (WKY) rats, the maximal increase in the SH rat being significantly greater than the increase in WKY rats. The increase in perfusion pressure in preparations from both strains of rats was prevented by losartan (0.1 microM) and unaffected by PD 123319 (0.1 microM), indicating that the vasoconstrictor action of angiotensin II is subserved by AT1 receptors. 3. Angiotensin II (0.1-3 microM) produced concentration-dependent enhancement of both stimulation-induced (S-I) efflux of [3H]-noradrenaline and stimulation-evoked vasoconstrictor responses in isolated preparations of caudal artery from both SH and WKY rats, in which the noradrenergic transmitter stores had been labelled with [3H]-noradrenaline. The maximum enhancement of S-I efflux produced by angiotensin II (1 microM) was significantly greater in artery preparations from WKY rats than in preparations from SH rats, whereas the maximum enhancement of stimulation-evoked vasoconstrictor responses was greater in preparations from SH rats than in those from WKY rats. 4. In artery preparations from both WKY and SH rats, the AT1 angiotensin II receptor antagonist, losartan (0.01 and 0.1 microM), reduced or abolished the enhancement of both S-I efflux and vasoconstrictor responses by 1 microM angiotensin II. 5. The combination of 0.01 microM losartan and 0.1 microM angiotensin II enhanced both the S-I efflux and stimulation-evoked vasoconstrictor response in caudal artery preparations from WKY rats, whereas 0.1 microM angiotensin alone was ineffective. The AT2 receptor antagonist PD 123319 (0.01 and 0.1 microM) prevented the enhancement of both S-I efflux and stimulation-evoked vasoconstrictor responses by the combination of angiotensin II and losartan. 6. In contrast to findings in WKY preparations and those previously obtained for arteries from another normotensive strain (Sprague-Dawley), in artery preparations from SH rats there was no synergistic interaction between losartan and angiotensin II. Rather, combinations of 0.1 microM angiotensin II and PD 123319 (both 0.01 and 0.1 microM) enhanced S-I [3H]-noradrenaline efflux, whereas 0.1 microM angiotensin II alone was without effect. Moreover, losartan (0.1 microM) prevented the enhancement of S-I efflux by the combination of angiotensin II and PD 123319. 7. The present findings indicate that in the caudal artery of WKY and SH rats, and as previously found in Sprague-Dawley preparations, angiotensin II receptors similar to the AT1B subtype subserve enhancement of transmitter noradrenaline release. 8. As previously suggested for Sprague-Dawley caudal artery preparations, the synergistic prejunctional interaction of losartan and 0.1 microM angiotensin II in caudal artery preparations from WKY rats may be due to either the unmasking by losartan of a latent population of angiotensin II receptors subserving facilitation of transmitter noradrenaline release, or blockade by losartan of an inhibitory action of angiotensin II on transmitter release. 9. The synergistic interaction of PD 123319 and 0.1 microM angiotensin II in caudal arteries of SH rats may also be explained by either of the mechanisms proposed for the normotensive strains, but the involvement of different receptor subtypes would need to be postulated for each of the proposed mechanisms.

Valsartan, a new angiotensin II antagonist for the treatment of essential hypertension: a comparative study of the efficacy and safety against amlodipine

OBJECTIVE

To compare the antihypertensive efficacy of a new angiotensin II antagonist, valsartan, with a reference therapy, amlodipine.

METHODS

One hundred sixty-eight adult outpatients with mild to moderate hypertension were randomly allocated in double-blind fashion and equal number to receive 80 mg valsartan or 5 mg amlodipine for 12 weeks. After 8 weeks of therapy, in patients whose blood pressure remained uncontrolled, 5 mg amlodipine was added to the initial therapy. Patients were assessed at 4, 8, and 12 weeks. The primary efficacy variable was change from baseline in mean sitting diastolic blood pressure at 8 weeks. Secondary variables included change in sitting systolic blood pressure and responder rates.

RESULTS

Both valsartan and amlodipine were effective at lowering blood pressure at 4, 8, and 12 weeks. Similar decreases were observed in both groups, with no statistically significant differences between the groups for any variable analyzed. For the primary variable the difference was 0.5 mm Hg in favor of valsartan (p = 0.68; 95% confidence interval, -2.7 to 1.7). Responder rates at 8 weeks were 66.7% for valsartan and 60.2% for amlodipine (p = 0.39). Both treatments were well tolerated. The incidence of drug-related dependent edema was somewhat higher in the amlodipine group, particularly at a dose of 10 mg per day (2.4% for 80 mg valsartan; 3.6% for 5 mg amlodipine; 0% for valsartan plus 5 mg amlodipine; 14.3% for 10 mg amlodipine).

CONCLUSIONS

The data show that valsartan is at least as effective as amlodipine in the treatment of mild to moderate hypertension. The results also show valsartan to be well tolerated and suggest that it is not associated with side effects characteristic of this comparator class, dihydropyridine calcium antagonists.

Clinical and hormonal effects of the new angiotensin II receptor antagonist LRB081

The renin-angiotensin system is a major contributor to the pathophysiology of cardiovascular diseases such as congestive heart failure and hypertension. Antagonizing angiotensin (Ang) II at the receptor site may produce fewer side effects than inhibition of the promiscuous converting enzyme. The present study was designed to assess in healthy human subjects the effect of LRB081, a new orally active AT1-receptor antagonist, on the pressor action of exogenous Ang II. At the same time, plasma hormones and drug levels were monitored. At 1-week intervals and in a double-blind randomized fashion, 8 male volunteers received three doses of LRB081 (10, 40, and 80 mg) and placebo. Blood pressure (BP) was measured at a finger by photoplethysmograph. The peak BP response to intravenous injection of a standard dose of Ang II was determined before and for < or = 24 h after administration of an oral dose of LRB081 or placebo. After drug administration, the blood BP response to Ang II was expressed in percent of the response before drug administration. At the same time, plasma renin activity (PRA), Ang II, aldosterone, catecholamine (radioassays), and drug levels (by high-performance liquid chromatography) were monitored. After LRB081 administration, a dose dependent inhibition of the BP response to Ang II was observed. Maximal inhibition of the systolic BP response was 54 +/- 3 (mean +/- SEM), 63 +/- 2, and 93 +/- 1% with 10, 40, and 80 mg LRB081, respectively. The time to peak was 3 h for 6 subjects and 4 and 6 h for 2 others. Preliminary plasma half-life (t1/2) was calculated at 2 h. With the highest dose, the inhibition remained significant for 24 h (31 +/- 5%, p < 0.05). Maximal BP-blocking effect and maximal plasma drug level coincided, suggesting that the unmetabolized LRB081 is responsible for the antagonistic effect. PRA and Ang II increased dose dependently after LRB081 intake. Aldosterone, epinephrine, and norepinephrine concentrations remained unchanged. No clinically significant adverse reaction was observed during the study. LRB081 is a well-tolerated, orally active, potent, and long-acting Ang II receptor antagonist. Unlike in the case of losartan, no active metabolite of LRB081 has been shown to be responsible for the main effects.

Effects of losartan on renal function in patients with essential hypertension

We examined the renal hemodynamic modifications induced by a selective angiotensin II (AII) AT1 receptor antagonist, losartan, in 10 patients with essential hypertension. In this single-blind study, renal hemodynamic parameters were determined twice (patients were their own controls) first after a 15-day single-blind placebo run-in period and again after a 1-month losartan period. The dosage of losartan was 50 mg/day. Glomerular filtration rate (GFR, inulin clearance), renal plasma flow [RPF; para-aminohippurate (PAH) clearance], microalbuminuria, sodium excretion, proximal sodium tubular reabsorption (lithium clearance), and acid uric metabolism were measured. After 1-month losartan treatment, systolic and diastolic BP (SBP, DBP) decreased significantly throughout the 210-min recording whereas heart rate (HR) was unchanged. GFR (100 +/- 19 vs. 96 +/- 17 ml/min/1.73 m2) and RPF (471 +/- 118 vs. 468 +/- 108 ml/ min/1.73 m2) were not altered by losartan. Rather than occurrence of any modification in filtration fraction (FF), a significant decrease in microalbuminuria was evident (57 +/- 77 vs. 40 +/- 59 mg/24 h, p < 0.05). Urinary sodium excretion was not modified, but an almost significant (p = 0.07) decrease in proximal sodium reabsorption was observed (72.9 +/- 7.7 vs. 68.1 +/- 6.4% of filtered sodium). The increase in renal uric clearance accounted for the significant decrease in serum uric acid (195 +/- 49 vs. 183 +/- 43 microM; p < 0.05). After 1-month losartan treatment, renal function was well preserved; the decrease in uric acid may be of clinical interest when adjuvent diuretic therapy is required.

Current drug treatment and treatment patterns with antihypertensive drugs

The 4 major classes of antihypertensive drugs are diuretics, beta-blockers, ACE inhibitors and calcium antagonists. The diuretics have recently regained prominence, largely due to the results of recent controlled trials. These trials in elderly patients demonstrated that low-dose diuretics were effective not only in preventing stroke but also in greatly reducing coronary-related events. Diuretics also decrease left ventricular mass more than the other major drug classes. In addition, they are the most effective drugs for use in combination therapy. By contrast, the safety of calcium antagonists has recently been questioned because of report of increased coronary morbidity and mortality. However, these adverse events may be restricted to the short-acting preparations, especially nifedipine, which causes cardiac stimulation. ACE inhibitors, like beta-blockers, are not only effective in reducing blood pressure, particularly when combined with a diuretic, but also improve angina and decrease postinfarction mortality. They also benefit congestive heart failure, stabilise or improve renal function in hypertensive and diabetic nephropathy and reduce albuminuria. Beta-Blockers are especially effective in reducing sudden cardiac death in patients with coronary heart disease, particularly in postinfarction patients. Final proof of the relative effectiveness of these drugs in preventing morbidity and mortality must await the outcome of large comparative trials currently under way. A recent national survey in the US found that more than 75% of hypertensive patients did not have their hypertension completely controlled. Possible reasons for this disturbing statistic are discussed along with suggestions for improvement.

Angiotensin II receptor antagonists: the prototype losartan

OBJECTIVE

To describe a new class of antihypertensive agents, the angiotensin II receptor antagonists, with emphasis on the prototype losartan. Pharmacokinetic data and clinical trials are reviewed, as well as adverse reactions, drug interactions, and dosing guidelines.

DATA SOURCES

A MEDLINE search of English-language literature published from 1966 through 1995 was performed. In addition, Merck and Co. provided bibliographic data on file for losartan.

STUDY SELECTION

Emphasis was placed on clinical and pharmacokinetic studies in humans. Controlled, double-blind studies were evaluated to assess the efficacy and adverse effect profile of losartan.

DATA SYNTHESIS

Losartan is a nonpeptide, competitive antagonist of the type I angiotensin II receptor. In comparative clinical trials, losartan appears to have antihypertensive efficacy similar to that of the angiotensin-converting enzyme (ACE) inhibitors. Losartan is well tolerated, with an adverse effect profile similar to that of placebo and a reduced incidence of cough versus that with ACE inhibitors. A combination product consisting of losartan 50 mg and hydrochlorothiazide 12.5 mg has also received approval for the treatment of hypertension. The combination product is not indicated for initial therapy, but is recommended for patients who do not respond adequately to losartan monotherapy. The angiotensin II receptor antagonists are also being investigated for beneficial effects in patients with ventricular hypertrophy, renal disease, and heart failure.

CONCLUSIONS

Losartan, the first angiotensin II receptor antagonist to receive approval for use in the US, appears to be an effective new antihypertensive agent with an adverse effect profile similar to that of placebo. Losartan may be an alternative for patients who cannot tolerate ACE inhibitors. However, the effect of losartan on mortality remains to be evaluated. The role of the angiotensin II receptor antagonists in areas such as ventricular hypertrophy, renal function, and heart failure has yet to be determined.

Toxicokinetic analysis of losartan during gestation and lactation in the rat

Previous developmental and reproductive toxicity studies in rats with losartan, a potent AT1-selective angiotensin II (AII) receptor antagonist, correlated maternal treatment during gestation day (GD) 15-20 with irreversible renal abnormalities in the F1 generation (Spence et al., '95a,b). Continued treatment through lactation was also associated with increases in pup mortality and decreases in pup body weights that persisted through weaning. The studies presented here were undertaken to quantify fetal and neonatal exposure to losartan when administered to the dam by oral gavage during early gestation, late gestation, and lactation. Following daily oral dosing of 135 mg/kg/day on GD6-15, fetal drug levels were negligible. However, losartan and its active metabolite, EXP3174 (L-158,641) were readily detectable in fetal plasma on GD 20 (estimated AUC values, 50.70 and 167.70 micrograms/hr/ml, respectively) and maternal milk during lactation (1.61 and 1.67 micrograms/ml, respectively). These studies suggest that the relative increased sensitivity of the fetus as compared to the neonate for losartan-induced renal lesions is related to the degree of exposure which is dependent on the time of administration (early gestation vs. late gestation/lactation) and the route of exposure (transplacental or through the milk). Furthermore, the maximum exposure to losartan and EXP3174 correlates with the ontogeny of the renin angiotensin system on approximately GD 17 and the critical period for losartan-induced renal lesions (GD15-20). The data support the hypothesis that the observed adverse fetal and neonatal effects are pharmacologically mediated, presumably through the lack of AT1 receptor stimulation.

Controlled trial of losartan given concomitantly with different doses of hydrochlorothiazide in hypertensive patients

The purpose of this trial was to evaluate the antihypertensive efficacy of the concomitant administration of selected doses of hydrochlorothiazide (HCTZ) on a background of losartan potassium (losartan) 50 mg, a selective angiotensin II receptor antagonist. Patients with essential hypertension ( > or = 95 mmHg inclusion criteria) with a mean sitting diastolic blood pressure (SiDBP) of 105 +/- 0.4 (S.E.) mmHg entered a 4-week, single-blind monotherapy period of losartan 50 mg once daily. At the end of the monotherapy period, patients whose blood pressure was adequately controlled were discontinued. Patients whose blood pressure was partially controlled based on a SiDBP > 92 mmHg entered a 12 week double-blind period and were randomly assigned to either receive placebo (n = 80), HCTZ 6.25 mg (n = 80), HCTZ 12.5 mg (n = 72) or HCTZ 25 mg (n = 80) in addition to losartan 50 mg. During the losartan monotherapy period, there was a 4 mmHg fall in SiDBP with a further fall of 5 mmHg after 12 weeks of double-blind therapy in the losartan/placebo control group. Based on the between group differences in BP change from the end of the losartan monotherapy period (baseline) to end of 12 weeks of double-blind, the concomitant administration of a very low dose of HCTZ (6.25 mg) with losartan did not significantly decrease SiDBP compared with the fall in blood pressure in the losartan/placebo control group (diff. between groups = -2 (95% C.I.[-4.1, +0.9] mmHg)). However, the concomitant administration of HCTZ 12.5 or 25 mg with losartan 50 mg resulted in significantly different (p < or = 0.05) reductions in diastolic blood pressure compared to the losartan/placebo group (diff. between groups = -4 (95% C.I. [-6.3, -1.1] mmHg) for 12.5mg combination group; -6 (95% C.I. [-8.3, -3.3]) mmHg for the HCTZ 25 mg combination group). The proportions of patients treated with losartan plus HCTZ 12.5 mg or 25 mg that achieved a trough SiDBP < 88 mmHg or a trough SiDBP > or = 88 mmHg but with a decrease of at least 5 mmHg were 71% and 83%, respectively. The percentage of clinical adverse experiences that were considered drug-related as assessed by the investigator were generally similar across all treatment groups. There were no reports of orthostatic hypotension in any of the treatment groups. Changes in serum glucose, potassium and uric acid were not appreciably different amongst the treatment groups. In summary, in patients with predominantly moderate to severe essential hypertension, the addition of HCTZ 12.5 mg or 25 mg to losartan 50 mg produced effective control of blood pressure in a substantial majority of patients who only partially responded to losartan monotherapy. There were no differences amongst the treatment groups with respect to drug-related adverse experiences in this trial.

Differential effects of oral losartan and enalapril on local venous and systemic pressor responses to angiotensin I and II in healthy men

This double-blind, placebo-controlled crossover study was designed to differentiate the pharmacodynamic effects of the angiotensin II receptor antagonist losartan from the angiotensin converting enzyme inhibitor enalapril. Effects of placebo, enalapril (10 mg), and losartan (20 and 100 mg) on local venous and systemic pressor responses to angiotensin I and II were compared in eight healthy male subjects. Treatments were administered orally approximately 4 hours before agonist infusions into a dorsal hand vein. Local changes in hand vein diameter and systemic blood pressure were monitored during the infusions. The 100 mg dose of losartan attenuated local venoconstrictor and systemic pressor responses to angiotensin I and II. In contrast, enalapril blocked only responses to angiotensin I. Both losartan and enalapril increased plasma renin concentration compared with placebo. These results are consistent with direct antagonism of angiotensin II receptors by losartan and with indirect effects of enalapril through inhibition of angiotensin converting enzyme.

Angiotensin converting enzyme (ACE) inhibitors and kinin metabolism: evidence that ACE inhibitors may inhibit a kininase other than ACE

1. Angiotensin converting enzyme (ACE) converts angiotensin I to angiotensin II, and also metabolizes bradykinin-(1-9) to bradykinin-(1-7) and bradykinin-(1-7) to bradykinin-(1-5). Increases in endogenous kinin levels may contribute to the therapeutic effects of ACE inhibitors. 2. ACE inhibitors increase vascular levels of both bradykinin-(1-9) and its ACE cleavage product bradykinin-(1-7), at doses below the threshold for ACE inhibition, leading to the proposal that ACE inhibitors may also inhibit a non-ACE kininase which cleaves both kinin peptides; this non-ACE kininase may be the major pathway of kinin metabolism in the vasculature and some other tissues. 3. In support of this proposal, ACE inhibitors potentiate bradykinin-(1-9) effects at doses which have little or no effect on ACE activity, as indicated by angiotensin I conversion to angiotensin II. ACE inhibitors also potentiate the actions of ACE-resistant kinin analogues, which may be susceptible to metabolism by a non-ACE kininase. 4. Identification and characterization of the putative non-ACE kininase which is inhibited by ACE inhibitors may reveal novel approaches to the tissue-specific modulation of kinin levels.

Effect of multiple doses of losartan on the pharmacokinetics of single doses of digoxin in healthy volunteers

1. Losartan (DuP 753, MK-954) is a novel, potent and highly selective AT1 angiotensin II receptor antagonist. The effect of multiple oral doses of losartan on digoxin pharmacokinetics was evaluated in healthy male subjects. 2. In a double-blind and randomized fashion, subjects received 50 mg losartan or placebo once daily for 15 days in each period. At least 7 days elapsed between the two treatment periods. On days 4 and 11 of each period, subjects also received a single 0.5 mg dose of digoxin intravenously and orally respectively. 3. Eleven of 13 subjects completed the study. Side effects were mild and transient (12 out of 13 subjects reported at least one adverse experience). During the study, no laboratory abnormalities were noted. 4. Multiple oral doses of losartan (50 mg daily) did not affect the pharmacokinetic parameters of 0.5 mg of digoxin i.v. AUC(0.48h) of immunoreactive digoxin during losartan 28.8 +/- 2.9 vs 28.5 +/- 3.9 ng ml-1 h during placebo; not significant, and 96 h urinary excretion [% dose] during losartan 54.0 +/- 7.2 vs 51.9 +/- 6.5% during placebo; not significant). Geometric mean ratios (90% confidence interval) for AUC and urinary excretion were respectively, 1.03 (0.98, 1.08) and 1.09 (0.98, 1.21). 5. Multiple oral doses of losartan did not affect the pharmacokinetic parameters of oral digoxin AUC(0.48 h) during losartan 23.6 +/- 3.7 ng ml-1 h vs 22.4 +/- 2.6 ng ml-1 h during placebo; not significant, Cmax 3.5 +/- 0.7 ng ml-1 with vs 3.1 +/- 0.5 ng ml-1 without losartan; not significant and tmax 0.6 +/- 0.2 h with vs 0.9 +/- 0.7 h without losartan; not significant, and 96 h urinary excretion [% dose] during losartan 51.2 +/- 6.3 vs 46.3 +/- 2.4% during placebo; not significant). Geometric mean ratios (90% confidence interval) for AUC and urinary excretion were respectively, 1.06 (0.98, 1.14) and 1.12 (0.97, 1.28). 6. We conclude that multiple oral doses of losartan (50 mg daily) do not alter the pharmacokinetics of immunoreactive digoxin, following either intravenous or oral digoxin. Furthermore, the co-administration of digoxin with losartan is well tolerated by healthy male volunteers.

Angiotensin II receptor antagonism: losartan - sites and mechanisms of action

This review surveys the basic pharmacology of angiotensin II receptors and their antagonism; reviews the existing clinical experience with losartan, the first approved nonpeptide angiotensin II antagonist; suggests other possible clinical areas for angiotensin II receptor antagonism; and compares angiotensin-converting enzyme inhibition with angiotensin receptor antagonism.

Additive effects of combined angiotensin-converting enzyme inhibition and angiotensin II antagonism on blood pressure and renin release in sodium-depleted normotensives

BACKGROUND

Angiotensin-converting enzyme (ACE) inhibitors do not decrease plasma angiotensin (Ang) II levels 24 hours after drug intake to the same extent as at peak. This intermittent partial "escape" is explained either by a renin-mediated reactive rise in plasma Ang I or by non-ACE-dependent Ang II generation. We therefore tested the hypothesis that a combination of ACE inhibition and Ang II blockade may have additive biological and hemodynamic effects.

METHODS AND RESULTS

In a single-dose, double-blind, randomized, four-way, crossover study, an Ang II antagonist (losartan 50 mg), an ACE inhibitor (captopril 50 mg), their combination, and matched placebos were orally administered to 12 normotensive male volunteers maintained in mild sodium depletion. When captopril 50 mg and losartan 50 mg were given alone, the magnitude of their effects on blood pressure, plasma active renin, Ang I, and aldosterone was similar, whereas the kinetics of their effects were different, reflecting differences in drug pharmacokinetics. The losartan-captopril combination completely suppressed the rise in plasma Ang II induced by losartan 2 hours after drug intake (3.3 +/- 3.6 pg/mL versus 20.3 +/- 19.1 pg/mL, respectively, P < .05). Six hours after drug intake, the losartan-captopril combination induced a significantly greater decrease in mean blood pressure than that produced by either losartan or captopril alone (73 +/- 7 mm Hg versus 79 +/- 8 mm Hg versus 81 +/- 7 mm Hg, respectively, P < .05). The maximum placebo-subtracted falls in mean blood pressure for the losartan-captopril combination, captopril 50 mg, and losartan 50 mg were 14 +/- 5 mm Hg, 10 +/- 3 mm Hg, and 9 +/- 6 mm Hg, respectively (F2.22 = 3.45, P < .05). The duration of the mean blood pressure fall was not prolonged by the combination. After combined losartan-captopril administration, the area under the plasma active renin versus time curve (0 to 24 hours) was significantly increased when compared with either losartan or captopril alone (6404 +/- 2961 pg.h.mL-1 versus 3105 +/- 1461 pg.h.mL-1 versus 2092 +/- 867 pg.h.mL-1, respectively, P < .05). The combination had no additive effects on plasma aldosterone decrease when compared with either losartan or captopril alone (58 +/- 17% versus 51 +/- 20% versus 53 +/- 21%, respectively, NS).

CONCLUSIONS

The combined administration of a standard single oral dose of an ACE inhibitor and an Ang II antagonist to mildly sodium-depleted normal subjects (1) had a major additive effect on plasma renin rise, (2) induced an additional mean blood pressure reduction, and (3) had no additive effect on plasma aldosterone fall.

Management of hypertensive urgencies and emergencies

Hypertensive emergency is a condition in which there is elevation of both systolic and diastolic blood pressure with the presence of acute target organ disease. Hypertensive urgency is a condition where the blood pressure is elevated (diastolic > 120 mmHg) with the absence of acute target organ disease. Hypertensive emergencies are best managed with parenteral drugs and careful intraarterial blood pressure monitoring. Hydralazine has been widely used in treatment of hypertension in eclampsia and preeclampsia, and its safety has been demonstrated in these patients. Sodium nitroprusside (SNP) has the most reliable antihypertensive activity, which begins immediately after its administration and ends when the infusion is stopped. As with diazoxide, it should be used with caution in patients with impaired cerebral flow. SNP is the preferred drug in obtaining controlled hypotension in patients undergoing neurovascular surgery. Intravenous nitroglycerin is useful in patients prone to myocardial ischemia, but should be avoided in patients with increased intracranial pressure. Esmolol is effective in controlling both supraventricular tachyarrhythmias and severe hypertension. Its short onset of duration of action make it useful in the emergent setting, but because of its negative inotropic effect its use should be avoided in patients with low cardiac output. Verapamil should not be used in patients with preexisting conduction abnormalities. Nicardipine is a potent arteriolar vasodilator without a significant direct depressant effect on myocardium. As with other afterload reducing agents, it should not be used in patients with severe aortic stenosis. Because angiotensin-converting enzyme (ACE) inhibitors generally cause cerebral vasodilatation, enalaprilat may be particularly beneficial for patients who are at high risk of developing cerebral hypotensive episodes secondary to impaired cerebral circulation. Fenoldopam, a selective post-synaptic dopaminergic receptor (DA1) has been shown to be effective in treating severe hypertension with a lower incidence of side effects than SNP. Hypertensive urgencies can usually be managed with oral agents. Oral nifedipine, captopril, clonidine, labetalol, prazosin, and nimodipine have all been shown to be effective in these situations.

Maintaining long-term control of blood pressure: the role of improved compliance

Mild-to-moderate essential hypertension is a major risk factor for stroke and cardiovascular mortality and morbidity. Morbidity can be reduced significantly by lowering high blood pressure, and with the effective antihypertensive drugs now available, it is ever more important to identify and treat the estimated 50 to 60 million hypertensive persons in the United States. Yet a high percentage of persons being treated stop taking their medication and refuse to comply with their therapeutic regimen. Many problems relate to maintaining long-term therapy in the hypertensive population. They include the cost of medication, a lack of written instructions, unclear instructions, noninvolvement of the patient in designing the treatment plan, lack of patient education about the disease, side effects, and inconvenient dosing schedules. Numerous studies have found that compliance increases as drug-dosage frequency decreases, as with the use of once-daily or sustained-release drug preparations. Other contributors to compliance include prescription-refill reminders, appointment reminders, simple written instructions about drug use, and patient education about the need for treatment and the consequences of noncompliance. Many classes of antihypertensive drugs are available, and more are in development. With such an extensive armamentarium available, all patients, regardless of coexisting medical conditions, should be able to be given effective, individualized antihypertensive therapy.

Antihypertensive therapy targeted to the needs of the patient: focus on the renin-angiotensin system; older and newer agents

Antihypertensive drug therapy can lower blood pressure and prolong life, but many hypertensive patients continue to develop further risk factors and to die prematurely of heart disease. Antihypertensive drugs can also interfere with the patient's quality of life, and many are not compatible with the concomitant medical conditions of the patient and the medications taken to treat them. For these reasons, the antihypertensive therapy selected should meet the specific and complete needs of each patient, not just treat the high blood pressure. An analysis of the drugs that inhibit the renin-angiotensin system suggests that several of these drugs have a more favorable therapeutic profile than other classes of hypotensive agents. The newly developed receptor-site-specific blockers are expected to be tolerated better by hypertensive patients and, consequently, to enhance their quality of life. The first of the new class of nonpeptide blockers of the AT1 receptor, losartan--which has no partial agonist activity--is likely to have the advantages of the angiotensin-converting enzyme inhibitors without their adverse effects, notably cough. In selected patients, the AT1-receptor blockers could become the drugs of first choice for the management of hypertension.

Evolving concepts in the management of hypertension

Currently, a plethora of antihypertensive medications exists. One concern about the long-term use of many of these agents is that adverse effects may offset their benefits. Despite the availability of many newer agents, blood pressure continues to be inadequately controlled in the majority of treated hypertensive patients, and many still remain at higher risk of premature death than the general population. More than 60% of treated hypertensive patients fail to attain blood pressures of < 140/90 mmHg. The major factors that permit a rational choice of medication include demographic considerations such as race and age, coexisting disease, safety, patient acceptance (quality of life), potential drug interactions, and additional salutary effects. The role of nondiuretic monotherapy is an integral component of this discussion. Preliminary data indicate that the use of calcium-channel blockers, converting-enzyme inhibitors, and AII-receptor antagonists constitutes excellent therapy in many patients. The effects of medication on the metabolic and lipid profiles are also considered.