Amlodipine therapy in pediatric patients with hypertension

Optimization of Personalized Amlodipine Dosing Strategies for Children Based on Pharmacokinetic Data from Chinese Male Adults and PBPK Modeling

For children, a special population who are continuously developing, a reasonable dosing strategy is the key to clinical therapy. Accurate dose predictions can help maximize efficacy and minimize pain in pediatrics. Methods: This study collected amlodipine pharmacokinetics (PK) data from 236 Chinese male adults and established a physiological pharmacokinetic (PBPK) model for adults using GastroPlus™. A PBPK model of pediatrics is constructed based on hepatic-to-body size and enzyme metabolism, used similar to the AUC_0-∞ to deduce the optimal dosage of amlodipine for children aged 1–16 years. A curve of continuous administration for 2-, 6-, 12-, 16-, and 25-year-olds and a personalized administration program for 6-year-olds were developed. Results: The results show that children could not establish uniform allometric amplification rules. The optimal doses were 0.10 mg·kg⁻¹ for ages 2–6 years and −0.0028 × Age + 0.1148 (mg/kg) for ages 7–16 years, r = 0.9941. The trend for continuous administration was consistent among different groups. In a 6-year-old child, a maintenance dose of 2.30 mg was used to increase the initial dose by 2.00 mg and the treatment dose by 1.00 mg to maintain stable plasma concentrations. Conclusions: A PBPK model based on enzyme metabolism can accurately predict the changes in the pharmacokinetic parameters of amlodipine in pediatrics. It can be used to support the optimization of clinical treatment plans in pediatrics.

Population Pharmacokinetics of Amlodipine in Hypertensive Children and Adolescents

A population pharmacokinetic study was conducted in 74 hypertensive children (mean age 10.4 +/- 4.4 years [mean +/- SD]) receiving amlodipine (mean dose 0.17 +/- 0.13 mg/kg/d) chronically. Multiple blood samples were obtained from each subject to characterize amlodipine pharmacokinetics. Plasma amlodipine concentrations were determined by liquid chromatography/mass spectrophotometry with multiple-reaction monitoring detection. Population pharmacokinetic analysis was performed using NONMEM. Amlodipine concentrations were similar in subjects dosed either once or twice daily. Amlodipine pharmacokinetics were well described by a 1-compartment model with first-order absorption and elimination. For a subject at the population median weight (45 kg), predicted apparent clearances (CL/F) were 23.7 L/h for males and 17.6 L/h for females, and the apparent volume of distribution (V/F) was 25.1 L/kg. Dosing frequency did not appear to affect amlodipine concentrations in children. Weight-adjusted CL/F and V/F of amlodipine in younger children were significantly greater than in older children, suggesting a need for higher doses when treating young children with amlodipine.

Management of hypertension in the young: role of antihypertensive medications

Traditionally, antihypertensive medications were used in few children or adolescents, usually just those with underlying renal or other organ system disease. However, with recent data suggesting that the incidence of primary hypertension may be increasing in the young, it is possible that more children and adolescents will be prescribed antihypertensive agents. This article will review currently available pediatric data on the use of calcium channel blockers, agents affecting the renin-angiotensin-aldosterone system and other classes of antihypertensive medications in children, highlighting appropriate indications and safety considerations. Guidelines for use of antihypertensive medications, including choice of initial agent and how to prescribe appropriately, will be presented.

Amlodipine toxicity in children less than 6 years of age: a dose-response analysis using national poison data system data

BACKGROUND

Amlodipine is a long-acting calcium channel blocker capable of producing hypotension and dysrhythmia in overdose. The toxic doses of amlodipine in children are unclear.

OBJECTIVES

The purposes of this study were to describe amlodipine poisoning in children and to determine whether a dose-response relationship could be detected in this population using standardized call data from United States (US) poison centers.

PATIENTS AND METHODS

1251 amlodipine-only ingestions in children < 6 years of age were reviewed. Cases with doses coded as "Exact" or "Estimated" and with dose, age, and medical outcome were analyzed (n = 678). Ingestions reported as a "taste or lick" (n = 53) were included as a dose of 1/10 of the dosage form involved. A clinically important response was defined as bradycardia, hypotension, dysrhythmia, conduction disturbance, or hyperglycemia. The risk of such responses was examined over four dosage intervals (< 2.5 mg, 2.5-5 mg, 5.1-10 mg, and > 10 mg).

RESULTS

The median estimated dose ingested was 5 mg (range 0.25-200 mg). Clinically important responses developed in 27 patients (3.98%), and the prevalence of such response significantly increased from 0% for the lowest to 11.1% for the highest dose interval (p = 0.001). The smallest dose to produce a clinically important response was 2.5 mg (0.15 mg/kg). Children who ingested > 10 mg were 4.4 times more likely to develop clinically important responses than those ingesting < or = 5 mg.

CONCLUSION

Hypotension may occur in children with amlodipine doses as low as 2.5 mg. The National Poison Data System might provide useful insights regarding dose-response.

Pediatric hypertension: recent trends and accomplishments, future challenges

Publication of the Fourth Report on high blood pressure (BP) in children and adolescents by the National High BP Education Program (NHBPEP) in 2004 has been followed by a remarkable increase in interest in pediatric hypertension. New data have emerged on the epidemiology of hypertension in the young, the influence of the childhood obesity epidemic on BP, how ambulatory BP monitoring (ABPM) can be used in evaluating elevated BP and the extent of hypertensive target-organ damage in the pediatric age group. Exciting new information on drug treatment of pediatric hypertension has been produced by industry-sponsored clinical trials of antihypertensive medications spurred by the FDA Modernization Act (FDAMA) and successor legislation. Despite these trends, recognition of elevated BP in children and adolescents by primary care providers remains problematic. This article will highlight these and other aspects of pediatric hypertension, hopefully providing a snapshot of where we are in early 2008, and pointing out areas where further work is needed in order to reduce the future burden of adult cardiovascular disease.

Effects of antihypertensive drugs on blood pressure and proteinuria in childhood

BACKGROUND

Historically, there have been few drug trials for antihypertensive treatment in childhood and recommendations have been extrapolated from data obtained in adulthood. During the last decade an increased awareness of the risks of childhood hypertension stimulated clinical trials of antihypertensive agents in children.

OBJECTIVE

The aim of this article is to systematically review the studies published between 1995 and 2006 that deal with the effect of antihypertensive drugs on childhood hypertension or proteinuria.

METHODS

Medline, Current Contents, personal files and reference lists were used as data sources.

RESULTS

Fifty-two out of 79 initially found reports were excluded. Consequently 27 articles were retained for the final analysis. The blood pressure reduction was similar with angiotensin-converting enzyme inhibitors (10.7/8.1 mmHg), angiotensin II receptor antagonists (10.5/6.9 mmHg) and calcium-channel blockers (9.3/7.2 mmHg). In addition angiotensin-converting enzyme inhibitors (by 49%) and angiotensin II receptor antagonists (by 59%) significantly reduced pathological proteinuria.

CONCLUSIONS

The blood pressure reduction of angiotensin-converting enzyme inhibitors, angiotensin II receptor antagonists and calcium-channel blockers is almost identical. In children with pathological proteinuria angiotensin-converting enzyme inhibitors or angiotensin II antagonists are superior to calcium-channel blockers.

Pharmacologic treatment of chronic pediatric hypertension

Improved recognition of the relationship between childhood and adult blood pressures and identification of end-organ damage in children, adolescents, and young adults with hypertension has led to increased focus by pediatricians and general practitioners on the detection, evaluation, and treatment of hypertension. Notably, detection, evaluation, and treatment of pediatric hypertension has increased significantly since the first Task Force Report on High Blood Pressure in Children and Adolescents in 1977 with advances in both nonpharmacologic and pharmacologic treatments.Angiotensin-converting enzyme inhibitors (e.g. captopril, enalapril, lisinopril, ramipril) and calcium channel antagonists (e.g. nifedipine, amlodipine, felodipine, isradipine) are the most commonly prescribed antihypertensive medications in children due to their low adverse-effect profiles. Diuretics (e.g. thiazide diuretics, loop diuretics, and potassium-sparing diuretics) are usually reserved as adjunct therapy. Newer agents, such as angiotensin receptor antagonists (e.g. irbesartan), are currently being studied in children and adolescents. These agents may be an option in children with chronic cough secondary to angiotensin-converting enzyme inhibitors. beta-Adrenoreceptor antagonists (e.g. propranolol, atenolol, metoprolol, and labetalol), alpha-adrenoreceptor antagonists, alpha-adrenoreceptor agonists, direct vasodilators, peripheral adrenoreceptor neuron agonists, and combination products are less commonly used in pediatric patients because of adverse events but may be an option in children unresponsive to calcium channel blockers, angiotensin converting-enzyme inhibitors, or angiotensin receptor blockers.

A randomized, placebo-controlled trial of amlodipine in children with hypertension

OBJECTIVES

Evaluation of the efficacy and safety of amlodipine in hypertensive children.

STUDY DESIGN

A randomized, double blinded, placebo-controlled, parallel-group, dose-ranging study was conducted at 49 centers in North and South America. The primary end point was the effect of amlodipine on systolic blood pressure (BP); secondary end points included the effect of amlodipine on diastolic BP, the effect of amlodipine as a function of dose and body size, and evaluation of safety.

RESULTS

We enrolled 268 hypertensive children (mean age, 12.1 +/- 3.3 years); 84 (31.3%) had primary hypertension, and 177 (66%) were boys. Amlodipine produced significantly greater reductions in systolic BP than placebo; these were -6.9 mm Hg for 2.5 mg daily (P=.045 vs placebo) and -8.7 mm Hg for 5 mg daily (P=.005 vs placebo). The underlying cause of hypertension had no effect on the response to amlodipine. There was a significant dose-response effect of amlodipine on both systolic and diastolic BP beginning at doses > or =0.06 mg/kg per day. Systolic BP < or =95(th) percentile was achieved in 34.6% of subjects with systolic hypertension. Amlodipine was well tolerated, with just 6 children withdrawn from treatment because of drug-related adverse events.

CONCLUSIONS

Amlodipine effectively lowers systolic BP in a dose-dependent manner in hypertensive children who require drug treatment.