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

Dopamine, Immunity, and Disease

The neurotransmitter dopamine is a key factor in central nervous system (CNS) function, regulating many processes including reward, movement, and cognition. Dopamine also regulates critical functions in peripheral organs, such as blood pressure, renal activity, and intestinal motility. Beyond these functions, a growing body of evidence indicates that dopamine is an important immunoregulatory factor. Most types of immune cells express dopamine receptors and other dopaminergic proteins, and many immune cells take up, produce, store, and/or release dopamine, suggesting that dopaminergic immunomodulation is important for immune function. Targeting these pathways could be a promising avenue for the treatment of inflammation and disease, but despite increasing research in this area, data on the specific effects of dopamine on many immune cells and disease processes remain inconsistent and poorly understood. Therefore, this review integrates the current knowledge of the role of dopamine in immune cell function and inflammatory signaling across systems. We also discuss the current understanding of dopaminergic regulation of immune signaling in the CNS and peripheral tissues, highlighting the role of dopaminergic immunomodulation in diseases such as Parkinson's disease, several neuropsychiatric conditions, neurologic human immunodeficiency virus, inflammatory bowel disease, rheumatoid arthritis, and others. Careful consideration is given to the influence of experimental design on results, and we note a number of areas in need of further research. Overall, this review integrates our knowledge of dopaminergic immunology at the cellular, tissue, and disease level and prompts the development of therapeutics and strategies targeted toward ameliorating disease through dopaminergic regulation of immunity. SIGNIFICANCE STATEMENT: Canonically, dopamine is recognized as a neurotransmitter involved in the regulation of movement, cognition, and reward. However, dopamine also acts as an immune modulator in the central nervous system and periphery. This review comprehensively assesses the current knowledge of dopaminergic immunomodulation and the role of dopamine in disease pathogenesis at the cellular and tissue level. This will provide broad access to this information across fields, identify areas in need of further investigation, and drive the development of dopaminergic therapeutic strategies.

Fenoldopam and renal hemodynamics in shiga toxin-related hemolytic uremic syndrome

BACKGROUND

Fenoldopam, a vasodilating agent, may represent a potential therapeutic opportunity to increase renal perfusion in those conditions where renal hemodynamics are severely impaired by vascular sub-occlusion, as, indeed, is the case in thrombotic microangiopathies.

METHODS

The renal resistance index (RRI) was measured, on and off fenoldopam, in 27 children with STEC-HUS.

RESULTS

A 12% decrease in RRI was observed on fenoldopam compared to off treatment without changes in the systemic hemodynamics and with no side effects.

CONCLUSIONS

If confirmed in larger series, fenoldopam may become an important addition to supportive care to reduce ischemic damage in STEC-HUS and improve long-term outcomes.

A positive-negative switching LC-MS/MS method for quantification of fenoldopam and its phase II metabolites: Applications to a pharmacokinetic study in rats

Fenoldopam is an approved drug used to treat hypotension. The purpose of this study is to develop and validate an LC-MS method to quantify fenoldopam and its major metabolites fenoldopam-glucuronide and fenoldopam-sulfate in plasma and apply the method to a pharmacokinetic study in rats. A Waters C18 column was used with 0.1% formic acid in acetonitrile and 0.1% formic acid in water as the mobile phases to elute the analytes. A positive-negative switching method was performed in a triple quadrupole mass spectrometer using Multiple Reaction Monitoring (MRM) mode. A one-step protein precipitation using methanol and ethyl acetate was successfully applied for plasma sample preparation. The method was validated following the FDA guidance. The results show that the LLOQ of fenoldopam, fenoldopam-glucuronide and fenoldopam-sulfate is 0.98, 9.75 and 0.98 nM, respectively. The intraday and interday variance is less than 8.4% and the accuracy is between 82.5 and 116.0 %. The extraction recovery for these three analytes ranged from 81.3 ± 4.1% to 113.9 ± 13.2%. There was no significant matrix effect and no significant degradation under the experimental conditions. PK studies showed that fenoldopam was rapidly eliminated (t1/2 = 0.63 ± 0.24 h) from the plasma and glucuronide is the major metabolite. This method was suitably selective and sensitive for pharmacokinetic and phase II metabolism studies.

Pharmacologic Control of Blood Pressure in Infants and Children

Alterations in blood pressure are common during the perioperative period in infants and children. Perioperative hypertension may be the result of renal failure, volume overload, or activation of the sympathetic nervous system. Concerns regarding end-organ effects or postoperative bleeding may mandate regulation of blood pressure. During the perioperative period, various pharmacologic agents have been used for blood pressure control including sodium nitroprusside, nitroglycerin, β-adrenergic antagonists, fenoldopam, and calcium channel antagonists. The following manuscript outlines the commonly used pharmacologic agents for perioperative BP including dosing regimens and adverse effect profiles. Previously published clinical trials are discussed and efficacy in the perioperative period reviewed.

Effects of Fenoldopam in the Pediatric Population: Fluid Status, Serum Biomarkers, and Hemodynamics: A Systematic Review and Meta-Analysis

Fluid overload is a frequent complication in children during critical illness. Fluid restriction and diuretic agents have been the mainstay therapies so far. Fenoldopam, a selective dopamine-1 receptor agonist, is a diuretic agent with promising effects in the pediatric population. The purpose of this meta-analysis is to evaluate the outcomes of pediatric patients who received fenoldopam. We hypothesized that the administration of fenoldopam will cause an increase in urine output and decrease in serum creatinine in this patient population. A comprehensive database search of PubMed, EMBASE, and Cochrane libraries from the databases' inception through December 2018 was undertaken. Independent reviewers selected appropriate studies and the reviewed data. A meta-analysis was then conducted to determine the effects of fenoldopam on hemodynamics, the amount of vasoactive support, and renal function in children under the critical care setting. The selected end points were measured prior to the administration of fenoldopam and 24 hours after the initiation of the infusion: urine output, serum creatinine, serum sodium, inotrope score, heart rate, central venous pressure, systolic blood pressure, and mean blood pressure. Forest plots were generated to demonstrate individual study data as well as pooled data for each end point. A total of five studies (three retrospective cohort studies, two randomized trials) with 121 patients were included for analysis. No significant difference was observed in urine output, inotrope score, systolic blood pressure, or mean blood pressure. There was a statistically significant increase in serum creatinine and central venous pressure. There was statistically significant decrease in serum sodium and heart rate, and central venous pressure. This meta-analysis did not identify significant renoprotective or vasodilator effects from fenoldopam in this patient population. Although mild electrolyte and hemodynamic changes were identified, larger studies are warranted to determine the clinical significance of fenoldopam in this patient population.

Role of dopamine and selective dopamine receptor agonists on mouse ductus arteriosus tone and responsiveness

BACKGROUND

Indomethacin treatment for patent ductus arteriosus (PDA) is associated with acute kidney injury (AKI). Fenoldopam, a dopamine (DA) DA₁-like receptor agonist dilates the renal vasculature and may preserve renal function during indomethacin treatment. However, limited information exists on DA receptor-mediated signaling in the ductus and fenoldopam may prevent ductus closure given its vasodilatory nature.

METHODS

DA receptor expression in CD-1 mouse vessels was analyzed by qPCR and immunohistochemistry. Concentration-response curves were established using pressure myography. Pretreatment with SCH23390 (DA₁-like receptor antagonist), phentolamine (α -adrenergic receptor antagonist) or indomethacin addressed mechanisms for DA-induced changes. Fenoldopam's effects on postnatal ductus closure were evaluated in vivo.

RESULTS

DA₁ receptors were expressed equally in ductus and aorta. High-dose DA induced modest vasoconstriction under newborn O₂ conditions. Phentolamine inhibited DA-induced constriction, while SCH23390 augmented constriction, consistent with a vasodilatory role for DA₁ receptors. Despite this, fenoldopam had little effect on ductus tone nor indomethacin- or O₂-induced constriction and did not impair postnatal closure in vivo.

CONCLUSION(S)

DA receptors are present in the ductus but have limited physiologic effects. DA-induced ductus vasoconstriction is mediated via α-adrenergic pathways. The absence of DA₁-mediated impairment of ductus closure supports the study of potential role for fenoldopam during PDA treatment.

A Practical Guide to the Management of Severe Hypertension in Children

Severe hypertension in children may result in life-threatening complications. Although there has not been extensive research in this area in children, and recommendations are mostly derived from adult data, in the last few years, there have been more pediatric studies on the safety and effectiveness of antihypertensives. The clinical presentation of a child with severe hypertension varies and may be completely asymptomatic or include signs and symptoms of end-organ damage. Treatment of a child with severe hypertension is emergent and should be done concomitantly with the evaluation.

Hypertensive Crisis in Pediatric Patients: An Overview

Hypertensive crisis can be a source of morbidity and mortality in the pediatric population. While the epidemiology has been difficult to pinpoint, it is well-known that secondary causes of pediatric hypertension contribute to a greater incidence of hypertensive crisis in pediatrics. Hypertensive crisis may manifest with non-specific symptoms as well as distinct and acute symptoms in the presence of end-organ damage. Hypertensive emergency, the form of hypertensive crisis with end-organ damage, may present with more severe symptoms and lead to permanent organ damage. Thus, it is crucial to evaluate any pediatric patient suspected of hypertensive emergency with a thorough workup while acutely treating the elevated blood pressure in a gradual manner. Management of hypertensive crisis is chosen based on the presence of end-organ damage and can range from fast-acting intravenous medication to oral medication for less severe cases. Treatment of such demands a careful balance between decreasing blood pressure in a gradual manner while preventing damage end-organ damage. In special situations, protocols have been established for treatment of hypertensive crisis, such as in the presence of endocrinologic neoplasms, monogenic causes of hypertension, renal diseases, and cardiac disease. With the advent of telehealth, clinicians are further able to extend their reach of care to emergency settings and aid emergency medical service (EMS) providers in real time. In addition, further updates on the evolving topic of hypertension in the pediatric population and novel drug development continues to improve outcomes and efficiency in diagnosis and management of hypertension and consequent hypertensive crisis.

Hypertensive crisis in children and adolescents

Hypertensive crisis is a relatively rare condition in children. However, if not treated, it might be life-threatening and lead to irreversible damage of vital organs. Clinical presentation of patients with hypertensive crisis can vary from very mild (hypertensive urgency) to severe symptoms (hypertensive emergency) despite similarly high blood pressure (BP). Individualized assessment of patients presenting with high BP with emphasis on the evaluation of end-organ damage rather than on the specific BP number is a key in guiding physician's initial management of a hypertensive crisis. The main aim of the treatment of hypertensive crisis is the prevention or treatment of life-threatening complications of hypertension-induced organ dysfunction, including neurologic, ophthalmologic, renal, and cardiac complications. While the treatment strategy must be directed toward the immediate reduction of BP to reduce the hypertensive damage to these organs, it should not be at a too fast rate to cause hypoperfusion of vital organs by an excessively rapid reduction of BP. Thus, intravenous continuous infusions rather than intravenous boluses of antihypertensive medications should be the preferable mode of initial treatment of children with hypertensive emergency.

Clinical Practice Guideline for Screening and Management of High Blood Pressure in Children and Adolescents

These pediatric hypertension guidelines are an update to the 2004 "Fourth Report on the Diagnosis, Evaluation, and Treatment of High Blood Pressure in Children and Adolescents." Significant changes in these guidelines include (1) the replacement of the term "prehypertension" with the term "elevated blood pressure," (2) new normative pediatric blood pressure (BP) tables based on normal-weight children, (3) a simplified screening table for identifying BPs needing further evaluation, (4) a simplified BP classification in adolescents ≥13 years of age that aligns with the forthcoming American Heart Association and American College of Cardiology adult BP guidelines, (5) a more limited recommendation to perform screening BP measurements only at preventive care visits, (6) streamlined recommendations on the initial evaluation and management of abnormal BPs, (7) an expanded role for ambulatory BP monitoring in the diagnosis and management of pediatric hypertension, and (8) revised recommendations on when to perform echocardiography in the evaluation of newly diagnosed hypertensive pediatric patients (generally only before medication initiation), along with a revised definition of left ventricular hypertrophy. These guidelines include 30 Key Action Statements and 27 additional recommendations derived from a comprehensive review of almost 15 000 published articles between January 2004 and July 2016. Each Key Action Statement includes level of evidence, benefit-harm relationship, and strength of recommendation. This clinical practice guideline, endorsed by the American Heart Association, is intended to foster a patient- and family-centered approach to care, reduce unnecessary and costly medical interventions, improve patient diagnoses and outcomes, support implementation, and provide direction for future research.

Hypertension in the Pediatric Intensive Care Unit

Hypertension in the pediatric intensive care unit (PICU) is common and it contributes to the overall morbidity and mortality. Patients may present with hypertensive emergencies or hypertension can manifest itself later in PICU course. Although hypertension can be seen in most patients during hospitalization, patients with some specific diseases and conditions are more prone to hypertension. Hypertension should be recognized promptly and treated accordingly. Different pathophysiologic mechanisms can be responsible for the hypertension and management differs based on the underlying etiology. Any patient with a hypertensive emergency must be admitted to PICU, and treatment and diagnostic workup should be initiated immediately.

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.

Hypertension in children with end-stage renal disease

This review summarizes current data on the epidemiology, pathophysiology, and treatment of hypertension (HTN) in children with end-stage renal disease (ESRD). Worldwide prevalence of ESRD ranges from 5.0 to 84.4 per million age-related population. HTN is present in 27-79% of children with ESRD, depending on the modality of renal replacement therapy and the exact definition of hypertension. Ambulatory BP monitoring has been recommended for the detection of HTN and evaluation of treatment effectiveness. HTN in dialyzed patients is mostly related to hypervolemia, sodium overload, activation of the renin-angiotensin-aldosterone system (RAAS) and sympathetic nervous system, impaired nitric oxide synthesis, reduced vitamin D levels, and effects of microRNA. In children undergoing chronic dialysis therapy, important factors include optimization of renal replacement therapy and preservation of residual renal function, allowing reduction of volume- and sodium-overload, along with appropriate drug treatment, particularly with calcium channel blockers, RAAS inhibitors, and loop diuretics.

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.

Therapy of acute hypertension in hospitalized children and adolescents

Acute hypertension (HTN) in hospitalized children and adolescents occurs relatively frequently, and in some cases, if not recognized and treated promptly, it can lead to hypertensive crisis with potentially significant morbidity and mortality. In contrast to adults, where acute HTN is most likely due to uncontrolled primary HTN, children and adolescents with acute HTN are more likely to have secondary HTN. This review will briefly cover evaluation of acute HTN and various age-specific etiologies of secondary HTN and provide more in-depth discussion on treatment targets, potential risks of acute HTN therapy, and available pediatric data on intravenous and oral antihypertensive agents, and it proposes treatment schema including unique therapy of specific secondary HTN scenarios.

Clevidipine for perioperative blood pressure control in infants and children

Various pharmacologic agents have been used for perioperative BP control in pediatric patients, including sodium nitroprusside, nitroglycerin, β-adrenergic antagonists, fenoldopam, and calcium channel antagonists. Of the calcium antagonists, the majority of the clinical experience remains with the dihydropyridine nicardipine. Clevidipine is a short-acting, intravenous calcium channel antagonist of the dihydropyridine class. It undergoes rapid metabolism by non-specific blood and tissue esterases with a half-life of less than 1 minute. As a dihydropyridine, its cellular and end-organ effects parallel those of nicardipine. The clevidipine trials in the adult population have demonstrated efficacy in rapidly controlling BP in various clinical scenarios with a favorable adverse effect profile similar to nicardipine. Data from large clinical trials regarding the safety and efficacy of clevidipine in children is lacking. This manuscript aims to review the commonly used pharmacologic agents for perioperative BP control in children, discuss the role of calcium channel antagonists such as nicardipine, and outline the preliminary data regarding clevidipine in the pediatric population.

Evaluation and management of pediatric hypertensive crises: hypertensive urgency and hypertensive emergencies

Hypertension (HTN) in the pediatric population is estimated to have a world-wide prevalence of 2%–5%. As with adults, pediatric patients with HTN can present with hypertensive crises include hypertensive urgency and hypertensive emergencies. However, pediatric blood pressure problems have a greater chance of being from secondary causes of HTN, as opposed to primary HTN, than in adults. Thorough evaluation of a child with a hypertensive emergency includes accurate blood pressure readings, complete and focused symptom history, and appropriate past medical, surgical, and family history. Physical exam should include height, weight, four-limb blood pressures, a general overall examination and especially detailed cardiovascular and neurological examinations, including fundoscopic examination. Initial work-up should typically include electrocardiography, chest X-ray, serum chemistries, complete blood count, and urinalysis. Initial management of hypertensive emergencies generally includes the use of intravenous or oral antihypertensive medications, as well as appropriate, typically outpatient, follow-up. Emergency department goals for hypertensive crises are to (1) safely lower blood pressure, and (2) treat/minimize acute end organ damage, while (3) identifying underlying etiology. Intravenous antihypertensive medications are the treatment modality of choice for hypertensive emergencies with the goal of reducing systolic blood pressure by 25% of the original value over an 8-hour period.

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.

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.

High-dose fenoldopam reduces postoperative neutrophil gelatinase-associated lipocaline and cystatin C levels in pediatric cardiac surgery

INTRODUCTION

The aim of the study was to evaluate the effects of high-dose fenoldopam, a selective dopamine-1 receptor, on renal function and organ perfusion during cardiopulmonary bypass (CPB) in infants with congenital heart disease (CHD).

METHODS

A prospective single-center randomized double-blind controlled trial was conducted in a pediatric cardiac surgery department. We randomized infants younger than 1 year with CHD and biventricular anatomy (with exclusion of isolated ventricular and atrial septal defect) to receive blindly a continuous infusion of fenoldopam at 1 μg/kg/min or placebo during CPB. Perioperative urinary and plasma levels of neutrophil gelatinase-associated lipocaline (NGAL), cystatin C (CysC), and creatinine were measured to assess renal injury after CPB.

RESULTS

We enrolled 80 patients: 40 received fenoldopam (group F) during CPB, and 40 received placebo (group P). A significant increase of urinary NGAL and CysC levels from baseline to intensive care unit (ICU) admission followed by restoration of normal values after 12 hours was observed in both groups. However, urinary NGAL and CysC values were significantly reduced at the end of surgery and 12 hours after ICU admission (uNGAL only) in group F compared with group P (P = 0.025 and 0.039, respectively). Plasma NGAL and CysC tended to increase from baseline to ICU admission in both groups, but they were not significantly different between the two groups. No differences were observed on urinary and plasma creatinine levels and on urine output between the two groups. Acute kidney injury (AKI) incidence in the postoperative period, as indicated by pRIFLE classification (pediatric score indicating Risk, Injury, Failure, Loss of function, and End-stage kidney disease level of renal damage) was 50% in group F and 72% in group P (P = 0.08; odds ratio (OR), 0.38; 95% confidence interval (CI), 0.14 to 1.02). A significant reduction in diuretics (furosemide) and vasodilators (phentolamine) administration was observed in group F (P = 0.0085; OR, 0.22; 95% CI, 0.07 to 0.7).

CONCLUSIONS

The treatment with high-dose fenoldopam during CPB in pediatric patients undergoing cardiac surgery for CHD with biventricular anatomy significantly decreased urinary levels of NGAL and CysC and reduced the use of diuretics and vasodilators during CPB.

TRIAL REGISTRATION

Clinical Trial.Gov NCT00982527.

The management of hypertensive emergencies in children after stem cell transplantation

AIM OF THE REVIEW

This work presents a short overview on the available data about drugs that are currently used to treat hypertensive emergencies in children with a focus on incidents after stem cell transplantation. It shows that the pediatric use of all hypotensive agents appears to be mainly based on personal experience of the attending physicians rather than on convincing clinical trials.

METHOD

A literature search was performed in MEDLINE, through PubMed, using the medical subject headings (MeSH) hypertensive emergencies, nifedipine, nicardipine, and children. Further articles were identified by checking cross-references of articles and books.

RESULTS

Hypertensive emergencies in children after stem cell transplantation usually have a renal etiology, because of the treatment with the calcineurin inhibitors cyclosporine and tacrolimus. In these severe cases an immediate action is necessary to avoid possible appearance or exacerbation of endorgan damage. Because of their mechanism of action and a potential nephroprotective effect calcium channel blockers may be particularly suitable in cases of hypertensive emergencies. An intravenous application of nifedipine may compensate the difficulties of accurate dosing, but keeping in mind possible severe side effects and the lack of published experience its use in children is at least questionable. Nicardipine appears to be the hypotensive agent of first choice. In adults, the treatment of hypertensive emergencies with intravenous nicardipine is well-documented, but for an evaluation of safety in pediatric use, the published studies and case reports appear to be barely adequate.

CONCLUSION

The actual treatment approaches vary widely, demonstrating the lack of hard science on which current treatment of hypertensive emergencies in children is based. The hypotensive agent for the individual situation should be chosen considering the properties, side effects, the limited experiences with its use and the patient's anamnesis.

The need for modeling and simulation to design clinical investigations in children

Recent legislation in the United States and Europe has resulted in an increased number of clinical trials of pharmaceutical agents in children. Creating a well-designed clinical trial that can be successfully completed is a challenging task, particularly as the study population includes younger and smaller children. Although there are some established principles for initially estimating appropriate doses of pharmaceutical agents in children based on known effective doses in adults, these rules are inadequate as the sole basis for designing a clinical trial in children. Factors such as maturation of metabolizing enzymes, relative physical maturation of the child, and altered absorption because of physiological differences in adults and children may contribute to alterations in the dose-exposure relationship. To account for the impact of these potential factors on a clinical trial, the use of modeling and simulation is necessary to anticipate the influence these variables can have on the desired clinical question to be addressed. The examples presented in this article highlight the principle that modeling and simulation is critical for adequately designing pediatrics trials.