Essential hypertension in pediatric patients may require pharmacological treatment. There is a need for efficacious, safe, and well-tolerated antihypertensive agents with a once-a-day dosing regimen in children and adolescents. The aim of the trial was to evaluate the dose-response and tolerability of the dihydropyridine calcium channel blocker, felodipine extended-release tablets (felodipine ER), given once daily to pediatric patients with essential hypertension. A randomized double-blind, parallel-group, multi-center clinical study comparing felodipine ER (2.5, 5, or 10 mg once daily) and placebo was performed on pediatric patients with a baseline systolic (SBP) or diastolic blood pressure (DBP) above the 95th percentile for age, sex, and height. Of 133 randomized patients, 128 (96.2%) completed the 3 weeks of double-blind treatment. The study population included 50% children 6-12 years of age or Tanner stage <or=3, 39% black, and 40% female patients. All doses of felodipine ER and placebo decreased both SBP and DBP. The 5-mg dose of felodipine ER resulted in a significant decline in trough sitting, standing, and supine DBP (placebo-adjusted, -4.6, -5.06, and -5.05 mmHg, respectively, P<0.05) compared with placebo. However, there was no significant decline in SBP. The 2.5- and 10-mg doses showed no significant differences compared with placebo in lowering BP. The effect of felodipine ER was comparable in patient subgroups by age, race, and gender. The drug was well tolerated. The study failed to show a dose response of felodipine ER in pediatric patients with essential hypertension. This finding might be explained in part by the limitations of study design. The spectrum of side effects in pediatric patients was comparable with that in adults, except for a lower incidence of peripheral edema. Further studies are needed to clarify the role of felodipine ER in the management of children and adolescents with essential hypertension.