Intravenous fenoldopam versus sodium nitroprusside in patients with severe hypertension

Calcium Channel Blockers in Acute Care: The Links and Missing Links Between Hemodynamic Effects and Outcome Evidence

Calcium channel blockers (CCBs) exert profound hemodynamic effects via blockage of calcium flux through voltage-gated calcium channels. CCBs are widely used in acute care to treat concerning, debilitating, or life-threatening hemodynamic changes in many patients. The overall literature suggests that, for systemic hemodynamics, although CCBs decrease blood pressure, they normally increase cardiac output; for regional hemodynamics, although they impair pressure autoregulation, they normally increase organ blood flow and tissue oxygenation. In acute care, CCBs exert therapeutic efficacy or improve outcomes in patients with aneurysmal subarachnoid hemorrhage, acute myocardial infarction and unstable angina, hypertensive crisis, perioperative hypertension, and atrial tachyarrhythmia. However, despite the clear links, there are missing links between the known hemodynamic effects and the reported outcome evidence, suggesting that further studies are needed for clarification. In this narrative review, we aim to discuss the hemodynamic effects and outcome evidence for CCBs, the links and missing links between these two domains, and the directions that merit future investigations.

Hypertensive Emergencies in the Emergency Department

Hypertension affects approximately one-third of Americans. An additional 30% are unaware that they harbor the disease. Significantly increased blood pressure constitutes a hypertensive emergency that could lead to end-organ damage. When organs such as the brain, heart, or kidney are affected, an intervention that will lower the blood pressure in several hours is indicated. Several pharmacologic options are available for treatment, with intravenous antihypertensive therapy being the cornerstone, but there is no standard of care. Careful consideration of each patient's specific complaint, history, and physical examination guides the emergency physician through the treatment algorithm.

Dopamine-1 Receptor Agonist: Renal Effects and Its Potential Role in the Management of Radiocontrast-Induced Nephropathy

Radiocontrast-induced nephropathy remains the third leading cause of hospital-acquired acute renal failure. Once established, this syndrome is associated with increased morbidity and mortality as well as increased health care costs. Recently, studies have been initiated to evaluate the potential of a selective dopamine-1 receptor agonist (fenoldopam) in ameliorating radiocontrast-induced renal failure. Selective dopamine-1 receptor agonists exhibit many desirable renal effects that support their use for the prophylaxis of radiocontrast-induced nephropathy, including decreases in renal vascular resistance and increases in renal blood flow, glomerular filtration, and sodium and water excretion. Several reports have documented a beneficial effect of fenoldopam administration in attenuating radiocontrast-induced nephropathy. In contrast, a recent multicenter, randomized study did not demonstrate a renoprotective effect of fenoldopam against radiocontrast-induced nephropathy. The presence of multiple confounders, however, precludes a definitive conclusion regarding the ability of fenoldopam to protect against radiocontrast-induced nephropathy. Additional studies are needed to properly evaluate the role of fenoldopam in radiocontrast-induced nephropathy prophylaxis.

Potential dopamine-1 receptor stimulation in hypertension management

The role of dopamine receptors in blood pressure regulation is well established. Genetic ablation of both dopamine D1-like receptor subtypes (D1, D5) and D2-like receptor subtypes (D2, D3, D4) results in a hypertensive phenotype in mice. This review focuses on the dopamine D1-like receptor subtypes D1 and D5 (especially D1 receptors), as they play a major role in regulating sodium homeostasis and blood pressure. Studies mostly describing the role of renal dopamine D1-like receptors are included, as the kidneys play a pivotal role in the maintenance of sodium homeostasis and the long-term regulation of blood pressure. We also attempt to describe the interaction between D1-like receptors and other proteins, especially angiotensin II type 1 and type 2 receptors, which are involved in the maintenance of sodium homeostasis and blood pressure. Finally, we discuss a new concept of renal D1 receptor regulation in hypertension that involves oxidative stress mechanisms.

Acute kidney injury following cardiac surgery: role of perioperative blood pressure control

BACKGROUND/AIMS

Patients who develop acute kidney injury (AKI) after cardiac surgery continue to have a high mortality rate. Although factors that predispose to postoperative renal dysfunction have been identified, this knowledge has not been associated with a substantial reduction in the incidence of this serious adverse event.

METHODS

This review uses the existing literature to explore the relationship between AKI and perioperative blood pressure (BP) control in cardiac surgery patients. The results of recent novel analyses are introduced, and the implications of these studies for the management of cardiac surgery patients in the perioperative period are discussed.

RESULTS

Preexisting isolated systolic hypertension and wide pulse pressure increase the risk of postoperative renal dysfunction in the cardiac surgery population. New data suggest that BP lability (i.e., BP excursions outside an acceptable physiologic range) during cardiac surgery may also be an important predictor of subsequent renal dysfunction.

CONCLUSION

Recently published data suggest that perioperative BP lability influences both the risk of postoperative renal dysfunction and 30-day mortality. Future studies will determine whether the use of agents that allow improved BP control within a desirable range will reduce the incidence of postoperative AKI in cardiac surgery patients.

Perioperative hypertension: a review of current and emerging therapeutic agents

Perioperative hypertension is a common problem encountered by anesthesiologists, surgeons, internists, and intensivists. Surprisingly, no randomized, placebo-controlled studies exist that show that the treatment of perioperative hypertension reduces morbidity or mortality. Nevertheless, perioperative hypertension requires careful management. While sodium nitroprusside and nitroglycerin are commonly used to treat these conditions, these agents are less than ideal. Intravenous beta blockers and calcium channel blockers have particular appeal in this setting.

Adverse drug reactions in patients with phaeochromocytoma: incidence, prevention and management

The dangers of phaeochromocytomas are mainly due to the capability of these neuroendocrine tumours to secrete large quantities of vasoactive catecholamines, thereby increasing blood pressure and causing other related adverse events or complications. Phaeochromocytomas are often missed, sometimes only becoming apparent during therapeutic interventions that provoke release or interfere with the disposition of catecholamines produced by the tumours. Because phaeochromocytomas are rare, evidence contraindicating use of specific drugs is largely anecdotal or based on case reports. The heterogeneous nature of the tumours also makes adverse reactions highly variable among patients. Some drugs, such as dopamine D(2) receptor antagonists (e.g. metoclopramide, veralipride) and beta-adrenergic receptor antagonists (beta-blockers) clearly carry high potential for adverse reactions, while others such as tricyclic antidepressants seem more inconsistent in producing complications. Other drugs capable of causing adverse reactions include monoamine oxidase inhibitors, sympathomimetics (e.g. ephedrine) and certain peptide and corticosteroid hormones (e.g. corticotropin, glucagon and glucocorticoids). Risks associated with contraindicated medications are easily minimised by adoption of appropriate safeguards (e.g. adrenoceptor blockade). Without such precautions, the state of cardiovascular vulnerability makes some drugs and manipulations employed during surgical anaesthesia particularly dangerous. Problems arise most often when drugs or therapeutic procedures are employed in patients in whom the tumour is not suspected. In such cases, it is extremely important for the clinician to recognise the possibility of an underlying catecholamine-producing tumour and to take the most appropriate steps to manage and treat adverse events and clinical complications.

Pharmacological interventions for hypertensive emergencies

BACKGROUND

Hypertensive emergencies, marked hypertension associated with acute end-organ damage, are life-threatening conditions. Many anti-hypertensive drugs have been used in these clinical settings. The benefits and harms of such treatment and the best first-line treatment are not known.

OBJECTIVES

To answer the following two questions using randomized controlled trials (RCTs): 1) does anti-hypertensive drug therapy as compared to placebo or no treatment affect mortality and morbidity in patients presenting with a hypertensive emergency? 2) Does one first-line antihypertensive drug class as compared to another antihypertensive drug class affect mortality and morbidity in these patients?

SEARCH STRATEGY

Electronic sources: MEDLINE, EMBASE, Cochrane clinical trial register. In addition, we searched for references in review articles and trials. We attempted to contact trialists. Most recent search August 2007.

SELECTION CRITERIA

All unconfounded, truly randomized trials that compare an antihypertensive drug versus placebo, no treatment, or another antihypertensive drug from a different class in patients presenting with a hypertensive emergency.

DATA COLLECTION AND ANALYSIS

Quality of concealment allocation was scored. Data on randomized patients, total serious adverse events, all-cause mortality, non-fatal cardiovascular events, withdrawals due to adverse events, length of follow-up, blood pressure and heart rate were extracted independently and cross checked.

MAIN RESULTS

Fifteen randomized controlled trials (representing 869 patients) met the inclusion criteria. Two trials included a placebo arm. All studies (except one) were open-label trials. Seven drug classes were evaluated in those trials: nitrates (9 trials), ACE-inhibitors (7), diuretics (3), calcium channel blockers (6), alpha-1 adrenergic antagonists (4), direct vasodilators (2) and dopamine agonists (1). Mortality event data were reported in 7 trials. No meta-analysis was performed for clinical outcomes, due to insufficient data. The pooled effect of 3 different anti-hypertensive drugs in one placebo-controlled trial showed a statistically significant greater reduction in both systolic [WMD -13, 95%CI -19,-7] and diastolic [WMD -8, 95%CI, -12,-3] blood pressure with antihypertensive therapy.

AUTHORS' CONCLUSIONS

There is no RCT evidence demonstrating that anti-hypertensive drugs reduce mortality or morbidity in patients with hypertensive emergencies. Furthermore, there is insufficient RCT evidence to determine which drug or drug class is most effective in reducing mortality and morbidity. There were some minor differences in the degree of blood pressure lowering when one class of antihypertensive drug is compared to another. However, the clinical significance is unknown. RCTs are needed to assess different drug classes to determine initial and longer term mortality and morbidity outcomes.

Drugs for the perioperative control of hypertension: current issues and future directions

The management of hypertension continues to pose important challenges. Recent developments have established the importance of more rigorous blood pressure control in the community. In the perioperative setting, hypertension has long been recognised as undesirable, although the adverse impact of high blood pressure on the acute risks of elective surgery may have been previously overstated.A number of agents and techniques are available to control blood pressure perioperatively. These include principally general and regional anaesthetics, alpha(2)-adrenoceptor agonists, peripheral alpha(1)- and beta-adrenoceptor antagonists, dihydropyridine calcium channel antagonists, dopamine D(1A)-receptor agonists (fenoldopam), and nitric oxide donors. Recent years have seen important developments in the receptor selectivity of new compounds and in pharmacokinetics, particularly esterase metabolism. The future study of genomics may enable us to identify patients at risk for hypertension-related adverse events and target therapies most effectively to these high-risk groups.

Current diagnosis and management of hypertensive emergency

The appropriate and timely evaluation and treatment of patients with severely elevated blood pressure is essential to avoid serious adverse outcomes. Most importantly, the distinction between a hypertensive emergency (crisis) and urgency needs to be made. A sudden elevation in systolic (SBP) and/or diastolic blood pressure (DBP) that is associated with acute end organ damage (cardiovascular, cerebrovascular, or renal) is defined as a hypertensive crisis or emergency. In contrast, acute elevation in SBP and/or DBP not associated with evidence of end organ damage is defined as hypertensive urgency. In patients with a hypertensive emergency, blood pressure control should be attained as expeditiously as possible with parenteral medications to prevent ongoing and potentially permanent end organ damage. In contrast, with hypertensive urgency, blood pressure control can be achieved with the use of oral medications within 24-48 hours. This paper reviews the management of hypertensive emergencies.

A Comparison of Fenoldopam with Dopamine and Sodium Nitroprusside in Patients Undergoing Cross-Clamping of the Abdominal Aorta

Fenoldopam, a selective dopamine-1-receptor agonist, decreases arterial blood pressure rapidly, with a brief duration of action similar to sodium nitroprusside (SNP), but in contrast to SNP, it increases renal blood flow. We compared the hemodynamic and renal effects of fenoldopam in patients undergoing abdominal aortic surgery requiring cross-clamping of the aorta with another therapeutic option, dopamine and SNP. Fenoldopam or 2 mcg x kg(-1) x min(-1) of dopamine and SNP was infused before incision in 60 randomly selected patients in a double-blind fashion. Hemodynamic variables were recorded before incision, immediately before clamping the aorta, 5 min after cross-clamp release and upon completion of surgery. Urine output, serum creatinine, and creatinine clearance were measured intraoperatively and postoperatively. Characteristics were compared between groups using two-sample rank sum test for continuous variables and Fisher's exact test for discrete variables. The occurrence of severe hypotension, maximum systolic blood pressure, and need for additional antihypertensive drugs were not different between the groups. Most intraoperative hemodynamic variables and all indices of renal function did not differ according to treatment. Therefore, fenoldopam has no therapeutic advantage compared with similar therapies in patients undergoing major vascular surgery involving cross-clamping of the aorta.

Characteristics and management of patients presenting to the emergency department with hypertensive urgency

Few studies have examined the characteristics of patients presenting with hypertensive urgency, factors contributing to their presentation, or their management. The time and cost associated with treatment are unknown. Retrospective analysis of 50 emergency department patients with hypertensive urgency (symptomatic blood pressure (BP) elevation focusing on systolic BP >180 mm Hg or diastolic BP >110 mm Hg) was performed. The hospital database was queried to determine the cost of the average treat-and-release visit. The mean age was 54.3+/-15.6 years; 64% were female; 46% were black; 90% had diagnosed hypertension. The mean presenting BP was 198+/-27.6/109+/-17.3 mm Hg; 66% had systolic BP >180 mm Hg, and 38% had diastolic BP >110 mm Hg. Initially, 30% were not on antihypertensives, and 28% were on monotherapy. Headache (42%) and dizziness (30%) were most frequently reported symptoms. Presentation was most often attributed to running out of medication (16%). IV and oral labetalol were given to 28% and 24% of patients, respectively. Fifty-six percent of patients had no change in baseline therapy at discharge. The average emergency department stay was 5 hours 17 minutes +/- 4 hours 27 minutes. The average cost for similar visits in 2004 was 1543 dollars per visit. Emergency department visits for hypertensive urgency are related mostly to noncompliance. Labetalol was the most frequently used therapy. Management in the primary care office could result in substantial cost savings.

Nicardipine versus Nitroprusside Infusion as Antihypertensive Therapy in Hypertensive Emergencies

This prospective study compared the efficacy of nicardipine and nitroprusside for treating hypertensive emergencies by measuring haemodynamic indices and serum catecholamine levels. Patients admitted to the emergency department with a hypertensive crisis and acute pulmonary oedema received intravenous infusions of nitroprusside (starting dose 1 μg/kg per min, n = 20) or nicardipine (starting dose 3 μg/kg per min, n = 20). Both groups experienced significant declines in systolic and diastolic blood pressure after treatment, but there were no significant time-dependent differences between the groups. Heart rate decreased in the nicardipine group and increased in the nitroprusside group, but neither change was significant. Respiration rate decreased and capillary oxygen saturation rate increased after treatment in both groups. Adrenaline and noradrenaline levels decreased significantly after treatment in both groups; noradrenaline levels were significantly decreased in the nicardipine-treated group compared with the nitroprusside-treated group. Injectable nicardipine is easy to use and as effective as nitroprusside for treating hypertensive crisis with acute pulmonary oedema.

Fenoldopam Versus Nitroprusside for the Treatment of Hypertensive Emergency

BACKGROUND

While sodium nitroprusside remains first-line therapy for hypertensive emergency (HEM), fenoldopam is increasingly being used because of its benign safety profile and potential renal protective effects.

OBJECTIVE

To compare the efficacy, safety, and cost of sodium nitroprusside versus fenoldopam for the treatment of HEM.

METHODS

This study was a retrospective analysis of consecutive patients with HEM admitted to a university-affiliated, level 1 trauma center from 1999 to 2001 and treated with either nitroprusside (n = 21) or fenoldopam (n = 22) for >30 minutes. Time to reach mean arterial pressure (MAP) goal, change in MAP over time, time to initiation of oral antihypertensive therapy, change in renal function, incidence of cyanide toxicity, and cost of therapy were compared between groups.

RESULTS

Demographic parameters were similar between groups, except renal failure, which was more prevalent in the fenoldopam group (10% vs 46%; p = 0.009). Neither the mean ± SD pretreatment MAP (nitroprusside 168 ± 19; fenoldopam 163 ± 19; p = 0.45), time to reach MAP goal (3.6 [0.4–30] vs 4 [1–22] h; p = 0.51), nor infusion duration (18 [0.7–113] vs 18 [3–74] h; p = 0.45) differed between the patient groups. Time to initiation of oral antihypertensive therapy was similar between nitroprusside- (4.5 h [0.5–22] and fenoldopam- (6.5 h [1–100] treated patients; p = 0.65). Additional intravenous antihypertensives were administered to 16 patients in each group (p = 0.80). Change in creatinine clearance and incidence of tachycardia did not differ between groups. No symptoms of cyanide toxicity were detected. Cost of drug therapy was greater with fenoldopam ($597.60, $199.20–6675.20); than nitroprusside ($2.66, $1.68–3.48; p < 0.001).

CONCLUSIONS

Treatment of HEM with fenoldopam appears to result in patient outcomes equivalent to those with nitroprusside but at a substantially higher cost. Further study is required to delineate the exact role of fenoldopam for treatment of HEM.

Clinical review: the management of hypertensive crises

Hypertension is an extremely common clinical problem, affecting approximately 50 million people in the USA and approximately 1 billion individuals worldwide. Approximately 1% of these patients will develop acute elevations in blood pressure at some point in their lifetime. A number of terms have been applied to severe hypertension, including hypertensive crises, emergencies, and urgencies. By definition, acute elevations in blood pressure that are associated with end-organ damage are called hypertensive crises. Immediate reduction in blood pressure is required only in patients with acute end-organ damage. This article reviews current concepts, and common misconceptions and pitfalls in the diagnosis and management of patients with acutely elevated blood pressure.

Management of patients with hypertensive urgencies and emergencies: a systematic review of the literature

BACKGROUND

Hypertensive urgencies and emergencies are common clinical occurrences in hypertensive patients. Treatment practices vary considerably to because of the lack of evidence supporting the use of one therapeutic agent over another. This paper was designed to review the evidence for various pharmacotherapeutic regimens in the management of hypertensive urgencies and emergencies, in terms of the agents' abilities to reach predetermined "safe" goal blood pressures (BPs), and to prevent adverse events.

METHODS

medline was searched from 1966 to 2001, and the reference lists of all the articles were retrieved and searched for relevant references, and experts in the field were contacted to identify other relevant studies. The Cochrane Library was also searched. Studies that were eligible for inclusion in this review were systematic reviews of randomized control trials (RCTs) and individual RCTs, all-or-none studies, systematic reviews of cohort studies and individual cohort studies, and outcomes research. No language restrictions were used.

RESULTS

None of the trials included in this review identified an optimal rate of BP lowering in hypertensive emergencies and urgencies. The definitions of hypertensive emergencies and urgencies were not consistent, but emergencies always involved target end-organ damage, and urgencies were without such damage. Measures of outcome were not uniform between studies. The 4 hypertensive emergency and 15 hypertensive urgency studies represented 236 and 1,074 patients, respectively. The evidence indicated a nonsignificant trend toward increased efficacy with urapidil compared to nitroprusside for hypertensive emergencies (number needed to treat [NNT] for urapidil to achieve target BP, 12; 95% confidence interval [95% CI], number of patients needed to harm [NNH], 5 to NNT, 40 compared to nitroprusside). Several medications were efficacious in treating hypertensive urgencies, including: nicardipine (NNT for nicardipine compared to plabebo, 2 in one study [95% CI, 1 to 5] and 1 in another [95% CI, 1 to 1]); lacidipine (NNT, 2; 95% CI, 1 to 8 for lacidipine vs nifedipine) or urapidil (NNT for urapidil compared to enalaprilat and nifedipine, 4; 95% CI, 3 to 6); and nitroprusside and fenoldopam (all patients reached target BP in 2 studies). The studies reported 2 cases of cerebral ischemia secondary to nifedipine.

CONCLUSIONS

Many effective agents exist for the treatment of hypertensive crises. Because of the lack of large randomized controlled trials, many questions remain unanswered, such as follow-up times and whether any of the studied agents have mortality benefit.

The diagnosis and management of hypertensive crises

Severe hypertension is a common clinical problem in the United States, encountered in various clinical settings. Although various terms have been applied to severe hypertension, such as hypertensive crises, emergencies, or urgencies, they are all characterized by acute elevations in BP that may be associated with end-organ damage (hypertensive crisis). The immediate reduction of BP is only required in patients with acute end-organ damage. Hypertension associated with cerebral infarction or intracerebral hemorrhage only rarely requires treatment. While nitroprusside is commonly used to treat severe hypertension, it is an extremely toxic drug that should only be used in rare circumstances. Furthermore, the short-acting calcium channel blocker nifedipine is associated with significant morbidity and should be avoided. Today, a wide range of pharmacologic alternatives are available to the practitioner to control severe hypertension. This article reviews some of the current concepts and common misconceptions in the management of patients with acutely elevated BP.

DA1-receptor stimulation by fenoldopam in the treatment of postcardiac surgical hypertension

BACKGROUND

Besides adequate analgesia, sedation and ventilation, postcardiac surgical hypertension has to be treated frequently with vasoactive drugs to avoid possible complications. In this study the hemodynamic effects of the DA1-receptor agonist fenoldopam (F) are compared to those of the Ca-channel antagonist nifedipine (N).

METHODS

Postoperatively, 64 CABG-patients with a mean arterial pressure (MAP) of more than 105 mmHg over 10 min were investigated. Patients with compromised ventricular function, insufficient surgical repair, arrhythmia or an ECG unable to detect myocardial ischemia were excluded. The study drugs (initial dosage: F: 0.8; N: 0.3 micrograms.kg-1.min-1) were given continuously via a central venous catheter to reduce and to maintain the MAP between 80 and 95 mmHg. Hemodynamic parameters were determined using thermodilution technique.

RESULTS

A significant reduction of the MAP (F: from 121 +/- 11 to 83 +/- 4, N: from 119 +/- 8 to 82 +/- 9 mmHg) and of the calculated systemic vascular resistance (SVR) (F: 2110 +/- 500 to 970 +/- 200, N:1980 +/- 660 to 1020 +/- 300 dyn.s.cm-5) were noted in both groups, whereby in the F group the therapeutic goal could be achieved more quickly with the dosage regimen chosen. As a result, a marked increase of heart rate, cardiac index and stroke volume index could be observed, which was more pronounced due to the initially stronger decrease of SVR with F. There was also a stronger decrease of pulmonary vascular resistance in the F group, but the indices of right ventricular function did not differ between the groups.

CONCLUSION

Fenoldopam seems to be an efficient alternative to nifedipine, especially because of its more rapid onset of action.

Fenoldopam: a new dopamine agonist for the treatment of hypertensive urgencies and emergencies

Fenoldopam is a selective dopamine agonist that is being considered for the parenteral treatment of systemic hypertension. In both an oral and parenteral form, the drug causes peripheral vasodilation by stimulating dopamine-1 adrenergic receptors. Its pharmaco-dynamics are reviewed in this article, along with the clinical experiences in patients with hypertensive urgencies and emergencies. Intravenous fenoldopam may provide advantages over sodium nitroprusside because it can induce both a diuresis and natriuresis, is not light sensitive, and is not associated with cyanide toxicity. There is no evidence for rebound hypertension after discontinuation of fenoldopam influsion.

Fenoldopam: a review of its pharmacodynamic and pharmacokinetic properties and intravenous clinical potential in the management of hypertensive urgencies and emergencies

Fenoldopam is a dopamine agonist that causes peripheral vasodilation via stimulation of dopamine 1 (D1) receptors. The efficacy of an intravenous infusion of fenoldopam in decreasing blood pressure in patients with a hypertensive urgency, including patients who developed hypertension after coronary artery bypass graft surgery, and in a small number of patients with hypertensive emergency, is similar to that of sodium nitroprusside. However, unlike sodium nitroprusside, fenoldopam also increases renal blood flow and causes diuresis and natriuresis. There is no evidence of rebound hypertension after stopping the infusion. As the tolerability profile of fenoldopam is generally similar to that of sodium nitroprusside, fenoldopam appears to be an effective alternative to sodium nitroprusside in the immediate treatment of patients who develop severe hypertension and in whom oral treatment is not practical. Fenoldopam may be particularly useful in patients who develop hypertension after coronary artery bypass graft surgery, but further studies are required to confirm its role in hypertensive emergency.

Fenoldopam mesylate versus sodium nitroprusside in the acute management of severe systemic hypertension

Thirty-three patients with severe systemic hypertension defined as a diastolic blood pressure (DBP) > or = 120 mm Hg were randomized in a single-blind fashion to be treated with either intravenous fenoldopam mesylate (FNP) or sodium nitroprusside (NTP). Fenoldopam mesylate and NTP infusion rates began at 0.1 microgram/kg/minute and 0.5 microgram/kg/minute, respectively and were titrated to achieve a goal DBP of between 95 and 110 mm Hg; or a reduction of at least 40 mm Hg if the baseline DBP was > 150 mm Hg. Fenoldopam mesylate (n = 15) reduced blood pressure from 217/145 +/- 6/5 to 187/112 +/- 6/3 mm Hg (P < .001) at an average infusion rate of 0.5 +/- 0.1 microgram/kg/minute. The average time to achieve goal DBP with FNP was 1.5 +/- 1.4 hours. Nitroprusside (n = 18) reduced blood pressure from 210/136 +/- 5/2 to 172/103 +/- 6/2 mm Hg (P < .001) at an average infusion rate of 1.2 +/- .24 micrograms/kg/minute. Nitroprusside response time averaged 2 +/- 2.5 hours. There was no significant difference between the magnitude of effect seen with either FNP or NTP; nor was there any difference observed in the adverse effect rates of the two agents. Fenoldopam mesylate and NTP demonstrate similar overall efficacy in the treatment of severe systemic hypertension.