Prolonged fenoldopam infusions in patients with mild to moderate hypertension: pharmacodynamic and pharmacokinetic effects

Efficacy and safety of fenoldopam for the treatment of hypertensive crises in children with kidney disease: a retrospective study

BACKGROUND

Hypertensive crises in children represent critical medical situations characterized by severe hypertension and potential organ damage. Fenoldopam, a dopaminergic medication, offers a viable therapeutic option for managing such clinical scenarios. We aimed to evaluate efficacy and safety of fenoldopam in the management of hypertensive urgencies and emergencies.

METHODS

This retrospective analysis focused on pediatric patients affected by acute or chronic kidney disease, aged 1 month-18 years, admitted to the Pediatric Nephrology and the Pediatric Intensive Care Unit at University-Hospital of Padua, Italy, who presented with a hypertensive crisis treated with fenoldopam between March 2010 and December 2022.

RESULTS

The study included 74 patients with median age 10 years (interquartile range [IQR] 4-15 years) who received 102 fenoldopam infusions. Seventy-two percent were already receiving antihypertensive treatment before admission. In all cases, fenoldopam was associated with a reduction of blood pressure (BP) after 8 h of treatment, but in 87% of patients reduction of the initial mean arterial pressure (MAP) was higher than 25% of calculated drop pressure. MAP normalized in 26% of cases after 24 h and in 35% after 48 h. Occurrence of hypotension was 7%, while hypokalemia was observed in 13% of cases. Patients who presented a MAP reduction not exceeding 25% of calculated drop pressure received a lower median fenoldopam dose (0.2 mcg/kg/min; IQR 0.1-0.2) compared with patients having a MAP reduction > 25% of calculated drop pressure (0.4 mcg/kg/min; IQR 0.2-0.6; p = 0.002).

CONCLUSIONS

Fenoldopam seems effective and safe for the treatment of hypertensive crises in children with kidney disease, at a starting dose of 0.2 mcg/kg/min. Strict BP monitoring is required to identify possible excessive drop pressure in the first hours of infusion.

Effects of fenoldopam on renal blood flow in hypertensive chronic kidney disease

BACKGROUND AND AIM

The synthetic drug fenoldopam mesylate (FM) may have a renoprotective role, and a "renal dose" of 0.1 µg/kg/min intravenous (IV) infusion of FM has been reported as able to increase renal blood flow without affecting systemic blood pressure. But conclusive data are still lacking. We aimed to investigate by color-Doppler ultrasonography the effects of IV administration of FM at this dosage in hypertensive chronic kidney disease (CKD) patients, and verify whether it may induce any systemic hemodynamic alteration.

METHODS

In 60 hypertensive CKD patients, we measured by duplex Doppler ultrasonography, at baseline and during infusion of 0.1 µg/kg/min of FM, the systolic and diastolic flow velocity (sampled at the renal hilum, intermediate section and origin of both renal arteries) and the intra-parenchymal renal resistive index (RRI) sampled on interlobular arteries of both kidneys. Patients were divided into four subgroups (I-IV) according to classification of National Kidney Foundation Kidney Disease Outcomes Quality Initiative (NKF-DOQI).

RESULTS

Infusion of 0.1 µg/kg/min FM significantly decreased the RRI (0.73 ± 0.05 vs. 0.65 ± 0.06; p < 0.0001) and increased the systolic and diastolic flow velocities in all renal artery tracts examined. No single episode of systemic hypotension was observed.

CONCLUSIONS

Very low-dose FM may significantly increase renal blood flow and exert a renal protective effect in hypertensive CKD patients. Infusion of FM at such low dosage appears also to be quite safe, even in CKD and hypertensive patients.

The Renin-Angiotensin and Renal Dopaminergic Systems Interact in Normotensive Humans

The renin-angiotensin-aldosterone (RAAS) and renal dopaminergic systems interact to maintain sodium balance. High NaCl intake increases renal synthesis of dopamine and dopaminergic receptor activity, decreasing epithelial sodium transport, whereas sodium deficit activates the RAAS, increasing epithelial sodium transport. We tested the hypothesis that attenuation of the natriuretic effect of dopamine D1-like receptors during salt restriction results in part from increased RAAS activity in seven salt-resistant normotensive adults using a double-blind placebo-controlled balanced crossover design. All subjects attained sodium balance on low (50 mmol Na(+)/day) and high (300 mmol Na(+)/day) NaCl diets, administered 4 weeks apart. Sodium, potassium, lithium, para-aminohippurate, and creatinine clearances were measured before, during, and after a 3-hour infusion of fenoldopam, a D1-like receptor agonist, with and without pretreatment with enalapril, an angiotensin converting enzyme inhibitor. On the high NaCl diet, fenoldopam-induced natriuresis was associated with the inhibition of renal proximal and distal tubule sodium transport. On the low NaCl diet, fenoldopam decreased renal distal tubule sodium transport but did not cause natriuresis. The addition of enalapril to fenoldopam restored the natriuretic effect of fenoldopam and its inhibitory effect on proximal tubule sodium transport. Thus, on a high NaCl diet fenoldopam causes natriuresis by inhibiting renal proximal and distal tubule transport, but on a low NaCl diet the increased RAAS activity prevents the D1-like receptor from inhibiting renal proximal tubule sodium transport, neutralizing the natriuretic effect of fenoldopam. These results demonstrate an interaction between the renin-angiotensin and renal dopaminergic systems in humans and highlight the influence of dietary NaCl on these interactions.

Rapid determination of fenoldopam in human plasma by UPLC-MS/MS for pharmacokinetic analysis in patients

We developed and validated a rapid, selective, and sensitive ultra-performance liquid-chromatography mass-spectrometry (UPLC-MS/MS) method for quantifying fenoldopam in human plasma for pharmacokinetic studies. Fenoldopam and the internal-standard (IS), oxazepam, were isolated from human plasma by liquid-liquid extraction using ethyl acetate after alkalization, and were separated on a 2.1×100 mm Acquity UPLC HSS T3 C18 column (inside diameter, 1.8 μm) using a mobile phase of water (0.05% formic acid) and acetonitrile gradient elution. The fenoldopam and IS were eluted at 1.07 and 2.32 min, respectively. Quantification was performed using positive-ion electrospray-ionization (ESI), and the fenoldopam and IS responses were optimized at the m/z 306.16→107.10 and m/z 287.1→241.01 transitions, respectively. The assay was validated over the linear range of 0.1-40 ng/mL fenoldopam with intra- and interassay precision <13.21%. The matrix effect of normal and hemolyzed plasma was 94.9-101.6%. Fenoldopam was stable for ≥34 days at -70 °C in normal and hemolyzed plasma containing ascorbic acid as a stabilizer. This method can be successfully applied in pharmacokinetic studies of fenoldopam in hypertensive patients.

Preliminary pharmacokinetics and cardiovascular effects of fenoldopam continuous rate infusion in six healthy dogs

Fenoldopam is a selective dopamine-1 receptor agonist that causes peripheral arterial vasodilation, increased renal blood flow, and diuresis. Enthusiasm exists for the use of fenoldopam in nonpolyuric kidney injury in dogs, although pharmacokinetic data are lacking. The purpose of this study was to collect basic pharmacokinetic and hemodynamic effect data for fenoldopam when administered to healthy awake dogs. Six healthy, awake beagles were given a 180-min fenoldopam constant rate infusion at 0.8 μg/kg per minute followed by a 120-min washout period. Citrated blood was collected during and after infusion for the measurement of plasma fenoldopam concentration by HPLC with mass spectrometry. Heart rate and indirect systolic blood pressure were concurrently measured. Mean ± SD, steady-state plasma fenoldopam concentrations of 20 ± 17 ng/mL were achieved within 10 min of starting the infusion. Area under the plasma concentration-time curve was 3678 ± 3030 ng/mL · min, and plasma clearance was 66 ± 43 mL/min per kg. Elimination was rapidly achieved in all dogs. Heart rate and systolic blood pressure were unaffected by the fenoldopam infusion. Based on the results of this study, further evaluation of the effects of fenoldopam in dogs at differing doses and in dogs with clinical conditions such as acute nonpolyuric kidney injury is warranted.

N-acetylcysteine and fenoldopam protect the renal function of patients with chronic renal insufficiency undergoing cardiac surgery

OBJECTIVE

To determine whether fenoldopam and N-acetylcysteine prevent renal deterioration and improve hospital outcome for patients with chronic renal insufficiency undergoing cardiac surgery.

DESIGN

Prospective, randomized, double-blinded, placebo-controlled trial.

SETTING

A community hospital that is a cardiac referral center.

PATIENTS

Seventy-nine adult patients with chronic renal insufficiency (creatinine clearance < or = 40 mL/min) who underwent cardiac surgery.

INTERVENTIONS

Group 1 received intravenous fenoldopam 0.1 microg/kg/min started at surgical induction and continued for 48 hrs. Group 2 received N-acetylcysteine 600 mg orally twice a day, from preoperative day 1 to postoperative day 1. Group 3 received both fenoldopam and N-acetylcysteine, and group 4 patients served as controls.

MEASUREMENTS AND MAIN RESULTS

Using multiple comparisons (analysis of variance) with change scores, and statistically adjusting for group differences in aortic cross-clamp time, use of intraoperative aprotinin, and preoperative use of statin, we found that the change in creatinine clearance from preoperative to postoperative day 3 was statistically less for group 1 (-1.47 mL/min +/- 2.06 SE, p = .0286) and for group 2 (-0.67 mL/min +/- 2.11 SE, p = .0198) and less but not quite significant for group 3 (-3.08 mL/min +/- 1.95 SE, p = .0891) compared with controls (-8.15 mL/min +/- 2.18 SE). Furthermore, the adjusted weight gain on postoperative day 3 was 5.55 kg +/- 1.00 SE (p = .0988) for group 1, 5.06 kg +/- 1.06 SE (p = .0631) for group 2, and 5.14 kg +/- .91 SE (p = .0445) for group 3 compared with 8.03 kg +/- 1.07 SE for group 4. However, there was no decrease in length of critical care or hospital stay or hospital costs. Finally, fenoldopam contributed to perioperative hypotension.

CONCLUSIONS

Perioperative fenoldopam and N-acetylcysteine abrogate the early postoperative decline in renal function of patients who have chronic renal insufficiency, although these agents do not affect other parameters of cardiac surgical outcome.

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.

The effects of intraoperative fenoldopam on renal blood flow and tubular function following suprarenal aortic cross-clamping

This study evaluated the effect of fenoldopam, a selective dopamine (DA1) agonist, on renal blood flow and renal tubular function following renal ischemia induced by suprarenal aortic cross-clamping. Twenty anesthetized research pigs received either fenoldopam (10 micro g/kg/min; n = 10) or saline ( n = 10) beginning 20 min before suprarenal aortic cross-clamping and continuing for 20 min after clamp release, for a total infusion time of 160 min (120-min cross-clamp). Recordings of renal blood flow, mean arterial pressure, and heart rate were taken at baseline, during cross-clamping, and immediately postclamp. Ischemic renal injury was evaluated by serum creatinine and by histologic grading of acute tubular necrosis. Treatment with fenoldopam increased renal blood flow in comparison to that in the control group ( p = 0.03). The mean creatinine increase from baseline at 6 hr and 18 hr after cross-clamp removal for the fenoldopam-treated group was significantly less than that in the control group ( p < 0.001). On histologic evaluation, the mean score for the degree of tubular necrosis was significantly higher in the control group ( p = 0.02), indicating less derangement of tubular morphology in the fenoldopam group. This study demonstrated that the intraoperative use of a continuous infusion of fenoldopam during suprarenal aortic cross-clamping results in increased renal blood flow, less postoperative rise in creatinine, and better preservation of tubular histology in the pig model.

Resistant hypertension, secondary hypertension, and hypertensive crises

Resistant hypertension, secondary hypertension, and hypertensive crises are uncommon but potentially dangerous forms of hypertension that are associated with an increased risk of complications such as myocardial infarction, heart failure, stroke, and renal failure. Appropriate diagnostic screening and selective drug or surgical management can reduce the risk of these complications dramatically. In compliant patients, resistant hypertension occurs most often in obese patients receiving inadequate diuretic therapy. In patients with clinical clues to the diagnosis, the best current screening test for renovascular hypertension is probably the ACE-inhibitor renal scintiscan. Angioplasty is considerably more successful in younger patients with fibrous dysplasia than in older patients with the atherosclerotic variety. Hypertensive crises are divided into BP urgencies and emergencies. In both settings, the reduction in BP should generally be gradual rather than abrupt, with no intent to acutely normalize the BP.