Randomized, prospective trial of fenoldopam vs sodium nitroprusside in the treatment of acute severe hypertension. Fenoldopam Study Group

Biodegradable Therapeutic Microneedle Patch for Rapid Antihypertensive Treatment

A hypertensive emergency causes severe cardiovascular diseases accompanied by acute target organ damage, requiring rapid and smooth blood pressure (BP) reduction. Current medicines for treating hypertensive emergencies, such as sodium nitroprusside (SNP), require careful dose control to avoid side effects (e.g., cyanide poisoning). The clinical administration of SNP using intravenous injection or drip further restrict its usage for first aid or self-aid in emergencies. Here, we developed an antihypertensive microneedle (aH-MN) technique to transdermally deliver SNP in combination with sodium thiosulfate (ST) as a cyanide antidote in a painless way. Dissolvable microneedles loaded with SNP and ST were fabricated via the centrifugation casting method, where the SNPs were stably packaged in microneedles and would be immediately released into the systemic circulation via subcutaneous capillaries when aH-MNs penetrated the skin. The antihypertensive effects were demonstrated on spontaneously hypertensive rat models. Rapid and potent BP reduction was achieved via aH-MN treatment, fulfilling clinical BP-control requirements for hypertensive emergencies. The side effects including skin irritation and target organ damage of aH-MN therapies were evaluated; the combinative delivery of ST effectively suppressed these side effects induced by the consecutive intake of SNP. This study introduces an efficient and patient-friendly antihypertensive therapy with a favorable side-effect profile, particularly a controllable and self-administrable approach to treat hypertensive emergencies.

Pharmacologic Treatment of Hypertensive Urgency in the Outpatient Setting: A Systematic Review

BACKGROUND

Hypertensive urgency (HU), defined as acute severe uncontrolled hypertension without end-organ damage, is a common condition. Despite its association with long-term morbidity and mortality, guidance regarding immediate management is sparse. Our objective was to summarize the evidence examining the effects of antihypertensive medications to treat.

METHODS

We searched the PubMed, Cochrane Central Register of Controlled Trials (CENTRAL), Database of Abstracts of Reviews of Effects (DARE), Cochrane Database of Systematic Reviews, Web of Science, Google Scholar, and Embase through May 2016.

STUDY SELECTION

We evaluated prospective controlled clinical trials, case-control studies, and cohort studies of HU in emergency room (ER) or clinic settings. We initially identified 11,223 published articles. We reviewed 10,748 titles and abstracts and identified 538 eligible articles. We assessed the full text for eligibility and included 31 articles written in English that were clinical trials or cohort studies and provided blood pressure data within 48 h of treatment. Studies were appraised for risk of bias using components recommended by the Cochrane Collaboration. The main outcome measured was blood pressure change with antihypertensive medications. Since studies were too diverse both clinically and methodologically to combine in a meta-analysis, tabular data and a narrative synthesis of studies are presented.

RESULTS

We identified only 20 double-blind randomized controlled trials and 12 cohort studies, with 262 participants in prospective controlled trials. However, we could not pool the results of studies. In addition, comorbidities and their potential contribution to long-term treatment of these subjects were not adequately addressed in any of the reviewed studies.

CONCLUSIONS

Longitudinal studies are still needed to determine how best to lower blood pressure in patients with HU. Longer-term management of individuals who have experienced HU continues to be an area requiring further study, especially as applicable to care from the generalist.

Evaluation and treatment of hypertensive crises in children

Hypertensive crises in children are medical emergencies that must be identified, evaluated, and treated promptly and appropriately to prevent end-organ injury and even death. Treatment in the acute setting typically includes continuous intravenous antihypertensive medications with monitoring in the intensive care unit setting. Medications commonly used to treat severe hypertension have been poorly studied in children. Dosing guidelines are available, although few pediatric-specific trials have been conducted to facilitate evidence-based therapy. Regardless of what medication is used, blood pressure should be lowered gradually to allow for accommodation of autoregulatory mechanisms and to prevent cerebral ischemia. Determining the underlying cause of the blood pressure elevation may be helpful in guiding therapy.

Sodium nitroprusside in 2014: A clinical concepts review

Sodium nitroprusside has been used in clinical practice as an arterial and venous vasodilator for 40 years. This prodrug reacts with physiologic sulfhydryl groups to release nitric oxide, causing rapid vasodilation, and acutely lowering blood pressure. It is used clinically in cardiac surgery, hypertensive crises, heart failure, vascular surgery, pediatric surgery, and other acute hemodynamic applications. In some practices, newer agents have replaced nitroprusside, either because they are more effective or because they have a more favorable side-effect profile. However, valid and adequately-powered efficacy studies are sparse and do not identify a superior agent for all indications. The cyanide anion release concurrent with nitroprusside administration is associated with potential cyanide accumulation and severe toxicity. Agents to ameliorate the untoward effects of cyanide are limited by various problems in their practicality and effectiveness. A new orally bioavailable antidote is sodium sulfanegen, which shows promise in reversing this toxicity. The unique effectiveness of nitroprusside as a titratable agent capable of rapid blood pressure control will likely maintain its utilization in clinical practice for the foreseeable future. Additional research will refine and perhaps expand indications for nitroprusside, while parallel investigation continues to develop effective antidotes for cyanide poisoning.

Hypertension and hypertensive encephalopathy

The definition of hypertension has continuously evolved over the last 50 years. Hypertension is currently defined as a blood pressure greater than 140/90mmHg. One in every four people in the US has been diagnosed with hypertension. The prevalence of hypertension increases further with age, affecting 75% of people over the age of 70. Hypertension is by far the most common risk factor identified in stroke patients. Hypertension causes pathologic changes in the walls of small (diameter<300 microns) arteries and arterioles usually at short branches of major arteries, which may result in either ischemic stroke or intracerebral hemorrhage. Reduction of blood pressure with diuretics, β-blockers, calcium channel blockers, and angiotensin-converting enzyme (ACE) inhibitors have all been shown to markedly reduce the incidence of stroke. Hypertensive emergency is defined as a blood pressure greater than 180/120mmHg with end organ dysfunction, such as chest pain, shortness of breath, encephalopathy, or focal neurologic deficits. Hypertensive encephalopathy is believed to be caused by acute failure of cerebrovascular autoregulation. Hypertensive emergency is treated with intravenous antihypertensive agents to reduce blood pressure by 25% within the first hour. Selective inhibition of cerebrovascular blood vessel permeability for the treatment of hypertensive emergency is beginning early clinical trials.

Hypertensive crisis in children

Hypertensive crisis is rare in children and is usually secondary to an underlying disease. There is strong evidence that the renin-angiotensin system plays an important role in the genesis of hypertensive crisis. An important principle in the management of children with hypertensive crisis is to determine if severe hypertension is chronic, acute, or acute-on-chronic. When it is associated with signs of end-organ damage such as encephalopathy, congestive cardiac failure or renal failure, there is an emergent need to lower blood pressures to 25-30% of the original value and then accomplish a gradual reduction in blood pressure. Precipitous drops in blood pressure can result in impairment of perfusion of vital organs. Medications commonly used to treat hypertensive crisis in children are nicardipine, labetalol and sodium nitroprusside. In this review, we discuss the pathophysiology, differential diagnosis and recent developments in management of hypertensive crisis in children.

Sodium nitroprusside may modulate Escherichia coli antioxidant enzyme expression by interacting with the ferric uptake regulator

Efforts to explore possible relationships between nitric oxide (NO) and antioxidant enzymes in an Escherichia coli model have uncovered a possible interaction between sodium nitroprusside (SNP), a potent, NO-donating drug, and the ferric uptake regulator (Fur), an iron(II)--dependent regulator of antioxidant and iron acquisition proteins present in Gram-negative bacteria. The enzymatic profiles of superoxide dismutase and hydroperoxidase during logarithmic phase of growth were studied via non-denaturing polyacrylamide gel electrophoresis and activity staining specific to each enzyme. Though NO is known to induce transcription of the manganese-bearing isozyme of SOD (MnSOD), treatment with SNP paradoxically suppressed MnSOD expression and greatly enhanced the activity of the iron-containing equivalent (FeSOD). Fur, one of six global regulators of MnSOD transcription, is uniquely capable of suppressing MnSOD while enhancing FeSOD expression through distinct mechanisms. We thus hypothesize that Fur is complacent in causing this behaviour and that the iron(II) component of SNP is activating Fur. E. coli was also treated with the SNP structural analogues, potassium ferricyanide (PFi) and potassium ferrocyanide (PFo). Remarkably, the ferrous PFo was capable of mimicking the SNP-related pattern, whereas the ferric PFi was not. As Fur depends upon ferrous iron for activation, we submit this observation of redox-specificity as preliminary supporting evidence for the hypothesized Fur-SNP interaction. Iron is an essential metal that the human innate immune system sequesters to prevent its use by invading pathogens. As NO is known to inhibit iron-bound Fur, and as activated Fur regulates iron uptake through feedback inhibition, we speculate that the administration of this drug may disrupt this strategic management of iron in favour of residing Gram-negative species by providing a source of iron in an otherwise iron-scarce environment capable of encouraging its own uptake. However, these gains may be counteracted by the oxidative consequences of iron and NO, as the former can catalyse the formation of toxic free radical species while the latter can inhibit enzymes and contribute to the formation of other toxic compounds. The potential consequences of SNP on microbial growth warrant future investigation.

Pharmacokinetics And Pharmacodynamics Of Fenoldopam Mesylate For Blood Pressure Control In Pediatric Patients

BACKGROUND

Fenoldopam mesylate, a selective dopamine1-receptor agonist, is used by intravenous infusion to treat hypertension in adults. Fenoldopam is not approved by the FDA for use in children; reports describing its use in pediatrics are limited. In a multi-institutional, placebo controlled, double-blind, multi-dose trial we determined the pharmacokinetic (PK) and pharmacodynamic (PD) characteristics and side-effect profile of fenoldopam in children.

METHODS

Seventy seven (77) children from 3 weeks to 12 years of age scheduled for surgery in which deliberate hypotension would be induced were enrolled. Patients were randomly assigned to one of five, blinded treatment groups (placebo or fenoldopam 0.05, 0.2, 0.8, or 3.2 mcg/kg/min iv) for a 30-minute interval after stabilization of anesthesia and placement of vascular catheters. Following the 30-minute blinded interval, investigators adjusted the fenoldopam dose to achieve a target mean arterial pressure in the open-label period until deliberate hypotension was no longer indicated (e.g., muscle-layer closure). Mean arterial pressure and heart rate were continuously monitored and were the primary endpoints.

RESULTS

Seventy-six children completed the trial. Fenoldopam at doses of 0.8 and 3.2 mcg/kg/min significantly reduced blood pressure (p < 0.05) during the blinded interval, and doses of 1.0-1.2 mcg/kg/min resulted in continued control of blood pressure during the open-label interval. Doses greater than 1.2 mcg/kg/min during the open-label period resulted in increasing heart rate without additional reduction in blood pressure. Fenoldopam was well-tolerated; side effects occurred in a minority of patients. The PK/PD relationship of fenoldopam in children was determined.

CONCLUSION

Fenoldopam is a rapid-acting, effective agent for intravenous control of blood pressure in children. The effective dose range is significantly higher in children undergoing anesthesia and surgery (0.8-1.2 mcg/kg/min) than as labeled for adults (0.05-0.3 mcg/kg/min). The PK and side-effect profiles for children and adults are similar.

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.

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.

Hypertensive crisis: hypertensive emergencies and urgencies

Hypertensive crisis is a serious condition that is associated with end-organ damage or may result in end-organ damage if left untreated. Causes of acute rises in blood pressure include medications,noncompliance, and poorly controlled chronic hypertension. Treatment of a hypertensive crisis should be tailored to each individual based on the extent of end-organ injury and comorbid conditions. Prompt and rapid reduction of blood pressure under continuous surveillance is essential in patients who have acute end-organ damage.

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.

Fenoldopam for renal protection in patients undergoing cardiopulmonary bypass

OBJECTIVE

To evaluate the possible protective effects of fenoldopam on renal function in patients undergoing cardiopulmonary bypass.

DESIGN

Prospective, randomized trial.

SETTING

University teaching hospital.

PARTICIPANTS

One hundred sixty consecutive patients with serum creatinine >1.5 mg/dL who underwent uncomplicated moderate hypothermic cardiopulmonary bypass for cardiac surgery.

INTERVENTIONS

A random group of 80 patients was managed conventionally (group A), whereas another random group of 80 patients received continuous intravenous administration of low-dose fenoldopam (0.1-0.3 microg/kg/min) during cardiopulmonary bypass and in the early postoperative period (group B).

MEASUREMENTS AND MAIN RESULTS

An improvement of postoperative renal parameters were observed only in group B: preoperative serum creatinine 1.82 +/- 0.2 versus 1.43 +/- 0.73 postoperatively (p < 0.001), preoperative creatinine clearance 51.34 +/- 22.26 versus 67.14 +/- 18.55 postoperatively (p < 0.001).

CONCLUSIONS

In this study, fenoldopam was an effective agent in the prevention of renal dysfunction after cardiopulmonary bypass.

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.

Using a dopamine type 1A receptor agonist in high-risk patients to ameliorate contrast-associated nephropathy

OBJECTIVE

The objective of our study was to evaluate the effects of fenoldopam mesylate, a dopamine type 1A receptor agonist and a potent renal vasodilator that markedly increases renal blood flow, on kidney function of patients who were receiving iodinated contrast material for an interventional procedure and thought to be at high risk of contrast-associated nephropathy.

MATERIALS AND METHODS

We retrospectively reviewed the records of all patients who received fenoldopam mesylate to determine the acute and, when possible, the longer term effects on kidney function.

RESULTS

Twenty-nine cases were reviewed. The average serum creatinine value before contrast administration was 2.55 mg/dL (range, 1.3-5.8 mg/dL) [corrected]. Twenty-four hours after contrast administration, serum creatinine was measured in 28 of the 29 patients. The serum creatinine values had decreased in 16 of the 28 patients by an average of 0.55 mg/dL [corrected]. In nine patients, the serum creatinine value had not changed. Two of the three increases in the serum creatinine value appear to have been caused primarily by problems that did not involve the contrast material.

CONCLUSION

The use of fenoldopam mesylate at appropriate doses offers patients at high risk for contrast-associated nephropathy a chance to avoid this complication. To learn the extent and true nature of the effect of fenoldopam mesylate in this patient population requires a rigorous scientific trial, which is currently underway.

Hypertensive emergencies: diagnosis and management

The treatment of hypertension is preventive medicine. This principle applies in the emergency room as well as the clinic. However, there are crucial contrasts between these two care settings related to specific goals of management for real emergencies and nonemergency conditions. In the emergency room, rapid triage is necessary to separate those who can safely be sent home for future clinic assessment from those who require immediate interventions including short stays in 24-hour observation units or hospitalization for more serious problems. This review focuses on decisions related to hypertension management in the emergency room and over brief periods of observation and treatment. Strategy is supported by evidence-based considerations whenever possible. Where outcome studies are not available, we rely on the rationale derived from relevant clinical research.

Hemodynamic and sympathetic effects of fenoldopam and sodium nitroprusside

BACKGROUND

Fenoldopam is a novel dopamine-1 receptor selective agonist that can be used as a vasodilator perioperatively to treat hypertension and to produce induced hypotension. We were interested to find out whether there were any differences between fenoldopam (FM) and sodium nitroprusside (SNP), one of the most popular vasodilators, in their effects on hemodynamics and sympathetic outflow using not only neuraxis intact but also baro-denervated animal models.

METHODS

A total of 60 New Zealand white rabbits were divided into two groups of 30 each: the neuraxis-intact group and the totally baro-denervated group. Each group was further divided into three groups of 10 each to receive SNP 10 microg x kg(-1), FM 10 microg x kg(-1) or FM 20 microg x kg(-1), respectively. Mean arterial pressure (MAP), heart rate (HR) and renal sympathetic nerve activity (RSNA) were recorded before and after intravenous (i.v.) administration of each agent. In addition, cardiac and sympathetic baroreflex sensitivity were assessed in the neuraxis-intact animals.

RESULTS

In the neuraxis-intact groups, although RSNA was increased to a similar extent in all three groups (P<0.01), the reduction of MAP with FM groups was significantly greater than with SNP (P<0.05). HR was increased only in the SNP group. Cardiac (HR) and sympathetic barosensitivity were significantly attenuated with FM 20 microg x kg(-1) as compared to the SNP group. In the baro-denervated groups, there were significant and similar degrees of reduction of MAP in all three group up to 1 min (P<0.01). MAP remained significantly decreased in the FM groups for 10 min (only 2 min with SNP) in both animal models.

CONCLUSIONS

Unlike sodium nitroprusside, fenoldopam attenuates both cardiac (heart rate) and sympathetic baroreflex sensitivity, which may explain the lack of rebound hypertension with fenoldopam. The offset of hypotensive effects of fenoldopam is a significantly slower process as compared to nitroprusside, and this may be an unfavorable feature of fenoldopam should overshoot of hypotension occur.

Reduced regional and global cerebral blood flow during fenoldopam-induced hypotension in volunteers

Dopamine has a wide spectrum of receptor and pharmacologic actions that may affect cerebral blood flow (CBF). A new, selective dopamine-1 agonist, fenoldopam, is a potent systemic vasodilator with moderate alpha(2)-receptor affinity. However, the effects of fenoldopam on the cerebral circulation are undefined. We therefore hypothesized that infusion of fenoldopam would decrease mean arterial blood pressure (MAP) and might concurrently decrease CBF via vascular alpha(2)-adrenoreceptor activation in awake volunteers. We studied nine healthy normotensive subjects, using positron emission tomography to measure CBF in multiple cortical and subcortical regions of interest. In addition, bioimpedance cardiac output and middle cerebral artery blood flow velocity were determined during fenoldopam-induced hypotension. Three men and four women, aged 25-43 yr, completed the study. Fenoldopam infused at 1.3 +/- 0.4 microg. kg(-1). min(-1) (mean +/- SD) reduced MAP 16% from baseline: from 94 (89-100) mm Hg (mean [95% confidence interval]) to 79 [74-85] mm Hg (P < 0.0001). During the fenoldopam infusion, both cardiac output (+39%), and heart rate (+45%) increased significantly, whereas global CBF decreased from baseline, 45.6 [35.6-58.5] mL. 100 g(-1). min(-1), to 37.7 [33.9-42.0] mL. 100 g(-1). min(-1) (P < 0.0001). Despite restoration of baseline MAP with a concurrent infusion of phenylephrine, global CBF remained decreased relative to baseline values at 37.9 [34.0-42.3] mL. 100 gm(-1). min(-1) (P < 0.0001). Changes in middle cerebral artery velocity did not correlate with positron emission tomography-measured changes of CBF induced by fenoldopam, with or without concurrent phenylephrine.

IMPLICATIONS

In awake volunteers with (presumably) intact cerebral autoregulation,fenoldopam-induced hypotension significantly decreased global cerebral bloodflow (CBF). Clinicians should be aware of these pharmacodynamic effects when choosing a vasodilator to control blood pressure, especially in situations where control of CBF, cerebral blood volume, and intracranial pressure are therapeutic priorities.

Preventing contrast-induced nephropathy with fenoldopam

Fenoldopam is an interesting orphan drug that is a variant of dopamine. It differs significantly from dopamine in that it is a specific agonist for the type I (DA-1) receptor. The DA-1 receptors are particularly prominent in the renal vasculature, renal tubules, mesenteric vasculature, and peripheral vessels. The DA-1 receptor stimulation vasodilates renal and peripheral vessels, causing a decrease in blood pressure and an increase in renal blood flow (RBF). Stimulation of the DA-1 receptors in the tubules causes an increase in sodium excretion, which gives rise to an increase in urine volume on the basis of a sodium natriuresis. Animal testing with fenoldopam has indicated that it is 6 times more potent than dopamine in its ability to decrease renal vascular resistance and increase RBF; this suggests that it could be a much more selective and potent renal protective agent against any toxin or stimulus that causes renal dysfunction by reducing RBF or increasing renal ischemia. The clinical activity of fenoldopam, which is administered intravenously, begins almost immediately and is clearly noticeable after 5 minutes. The drug has no rebound effect, and its use can be stopped at any time. The protocol for the use of fenoldopam as a renal protective agent (performed at the University of Minnesota) involves starting an intravenous fenoldopam infusion 2 hours before the procedure at a rate of 0.1 microg/kg/min and increasing the dose in increments of 0.1 microg/kg/min every 20 minutes, until a rate of 0.5 microg/kg/min is reached or the systolic blood pressure falls more than 40 mm Hg (or below 110 mm Hg). Any infusion level at or above 0.1 microg/kg/min is considered acceptable because the response in individual patients varies so widely. The fenoldopam infusion is maintained at the maximum rate throughout the procedure and for up to 4 hours after the end of the contrast administration. At the University of Minnesota, we have had anecdotal experience using the drug in 29 patients. The drug was used for patients who were thought to be at the highest risk for contrast-induced nephropathy, ie, patients who have both diabetes and pre-existing renal failure. In this small group of patients in whom hydration and other variables were not controlled, there was a startling lack of contrast-induced creatinine increase at any point during the 24 to 48 hours after the administration of contrast in all but 1 patient. Our experience suggests that fenoldopam may be of distinct benefit to high-risk patients who need intravascular contrast, especially those who may receive a large contrast dose, such as patients undergoing peripheral or coronary angiography and intervention and/or computed tomography. Although it is impossible on the basis of simple anecdotal case reports to determine whether or not the drug was the primary reason that such a marked protective effect was seen, the results are promising enough to indicate that a careful, prospective, randomized trial of fenoldopam versus hydration is warranted.

Oliguria in the ICU. Systematic approach to diagnosis and treatment

Perioperative oliguria is common but rarely implies acute renal failure. We should interpret oliguria as a sign of intravascular hypovolemia and treat it as prerenal until proven otherwise. On the other hand, the absence of oliguria does not exclude acute renal failure. The most reliable clinical indicator of progressive renal dysfunction is a serial decline in creatinine clearance estimation, a measure of glomerular filtration rate.

Fenoldopam for controlled hypotension during spinal fusion in children and adolescents

Fenoldopam is a dopamine1 agonist whose pharmacological effects include vasodilation of the vascular beds of the kidney, mesentery, skeletal muscle, and coronary systems, resulting in a decrease in systemic vascular resistance and mean arterial pressure. The current retrospective review outlines the use of fenoldopam for controlled hypotension during anterior or posterior spinal fusion in 10 children and adolescents, aged 8-14 years and weighing 22-61 kg. Fenoldopam was infused at a starting dose of 0.3-0.5 microg.kg-1. min-1 and increased incrementally to achieve a mean arterial pressure (MAP) of 50-65 mmHg. The desired MAP was achieved in 4-11 min (7+/-2.5 min). The fenoldopam infusion was administered for 135-225 min (160+/-25 min) in doses ranging from 0.2 to 2.5 microg. kg-1.min-1. The mean fenoldopam infusion rate for the 10 cases varied from 0.5 to 1.4 microg.kg-1.min-1 (1.0+/-0.3 microg.kg-1. min-1). No excessive hypotension or clinically significant adverse effects were noted. Statistically significant, but clinically insignificant, increases in heart rate and decreases in PaO2 were noted during the fenoldopam infusion. The baseline heart rate increased from 87+/-13 b.min-1 to a maximum of 114+/-16 b.min-1 (P < 0.0001) during the fenoldopam infusion. In the six patients undergoing posterior spinal fusion, the baseline PaO2 decreased from 232+/-7 mmHg to a low of 199+/-11 mmHg (P=0.0004) during the fenoldopam infusion. Fenoldopam can be used to provide controlled hypotension during spinal surgery in children and adolescents. Future studies, with direct comparison to other commonly used agents, are needed to better define its advantages and disadvantages as well as its effects on estimated blood loss.

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.

Fenoldopam, a dopamine agonist, for hypertensive emergency: a multicenter randomized trial. Fenoldopam Study Group

Despite successful therapies for chronic hypertension, hospital admissions for hypertensive emergency more than tripled between 1983 and 1992.

OBJECTIVE

To examine the safety and efficacy of fenoldopam, the first antihypertensive with selective and specific action on vascular dopamine (DA1) receptors, in a clinical trial involving emergency department patients with true hypertensive emergencies.

METHODS

Patients with a sustained diastolic blood pressure (DBP) of > or =120 mm Hg and evidence of target organ compromise were randomized in a double-blinded manner to one of four fixed doses of intravenous fenoldopam (0.01, 0.03, 0.1, or 0.3 microg/kg/min) for 24 hours. The primary endpoint was the magnitude of DBP reduction in each of the three higher-dose groups after four hours of fenoldopam treatment compared with the lowest-dose group.

RESULTS

One hundred seven participants from 21 centers were enrolled, and 94 patients received fenoldopam. Evidence of acute target-organ damage included new renal dysfunction or hematuria (50%), acute congestive heart failure or myocardial ischemia (48%), and papilledema or grade III-IV hypertensive retinopathy (34%). The DBP decreased in a dose-dependent fashion, with significant differences between the 0.1- and 0.3-microg/kg/min groups compared with the lowest-dose group. Treatment was well tolerated, and there were no deaths or serious adverse events during follow-up, up to 48 hours. All patients were successfully transitioned to oral or transdermal antihypertensives with maintenance of blood pressure control.

CONCLUSIONS

Fenoldopam safely and effectively lowers blood pressure in a dose-dependent manner in patients with hypertensive emergencies. Observations supporting potential risk factors for hypertensive emergency are discussed.

In vivo venodilator action of fenoldopam, a dopamine D(1)-receptor agonist

The effects of the dopamine D(1)-receptor agonist fenoldopam were compared with those of the D(2)-receptor agonist R(-)-propylnorapomorphine and vehicle on mean arterial pressure (MAP), mean circulatory filling pressure (MCFP, the driving force of venous return), arterial resistance (R(a)), venous resistance (R(v)), heart rate (HR) and cardiac output (CO) in groups of thiobutabarbitone-anaesthetized rats pre-treated with i.v. injection of mecamylamine (3.7 micromol kg(-1)) and continuously infused with noradrenaline (6.8 nmol kg(-1) min(-1)). The vehicle did not alter any haemodynamic variables. All doses of fenoldopam (0.5, 2 and 16 microgram kg(-1) min(-1)) reduced MAP, R(a) and R(v), and increased CO. At the highest dose, fenoldopam also increased HR and reduced MCFP. All doses of R(-)-propylnorapomorphine (0.5, 2 and 16 microgram kg(-1) min(-1)) increased MAP but did not significantly alter CO, R(v) and MCFP. Both R(a) and HR were increased by the highest dose of R(-)-propylnorapomorphine. Our results indicate that fenoldopam reduces MAP and MCFP, and markedly increases CO through reductions of arterial and venous resistances. The effects of fenoldopam in dilating arterial resistance and capacitance vessels were similar. In contrast, R(-)-propylnorapomorphine elevates MAP through an increase in arterial resistance but has minimal effects on CO, MCFP and venous resistance. Both drugs have a small direct, positive chronotropic action at the highest dose.

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.