Inclusion Criteria:

• Age 12 months to 16 years inclusive (AS OF MARCH 2007 ONLY SUBJECTS AGED 12 MONTHS TO 5 YEARS ARE BEING ACCEPTED)
• Signed parental/guardian informed consent and assent from the subject
• Current treatment for hypertension, OR, if not currently treated for hypertension, SBP or DBP greater than or equal to 95th percentile for gender and height-for-age, OR, if not currently treated for hypertension, SBP or DBP greater than or equal to 90th percentile for gender and height-for-age and diabetic or having a family history of hypertension
• Glomerular filtration rate (GFR) greater than or equal to 30 mL/min/1.73 m2, estimated using the Schwartz equation
• Sexually active females of child-bearing potential must be practicing an acceptable method of birth control
• Negative serum beta-HCG at screening and at admission (female of child-bearing potential only)

Exclusion Criteria:

• Clinically significant cardiac, gastrointestinal, hematologic, hepatic or hepatobiliary, neurologic, or pulmonary (except asthma) disorder
• History of severe or symptomatic hypertension associated with stroke, seizures, encephalopathy, or other significant neurologic findings within 1 year prior to screening
• Current treatment with more than 2 antihypertensive medications
• Secondary hypertension from uncorrected coarctation of the aorta, bilateral renal artery stenosis, or unilateral renal artery stenosis in a single kidney
• Serum albumin < 2.5 g/dL
• Major organ or bone marrow transplantation except for prior kidney transplantation of at least 6 months and with stable renal function meeting the inclusion criteria