Pharmacokinetics (PK) of Liquid Hydroxyurea in Pediatric Patients With Sickle Cell Anemia

For Both Arms:

Pharmacokinetics and Relative Bioavailability of a Liquid Formulation of Hydroxyurea in
Pediatric Patients with Sickle Cell

- The study participant will be a pediatric (male or female) participant with sickle
cell anemia with laboratory (i.e. electrophoretic, chromatographic or DNA)
confirmation of the diagnosis of Hemoglobin SS or Sβ0thalassemia.

- Weight ≥ 10 kg.

- Participants may or may not be currently receiving hydroxyurea. If participants are
taking hydroxyurea, the last dose must be no less than 24 hours prior to the start of
the study.

- Participant is in the "well" state (i.e. at least 2 weeks since the last
vaso-occlusive crisis, acute chest syndrome episode, or splenic sequestration
episode).

- Clinical evidence of normal gastrointestinal function and structure.

- No clinical evidence of hepatic compromise including transaminases no more than 3
times the upper limit of normal.

- A glomerular filtration rate (GFR--estimated from serum creatinine using
age-appropriate, validated equations such as the Schwartz equation) > 70
ml/min/1.73m2 and no known renal impairment (creatinine no more than 1.5 times the
upper limit of normal for age in the screening laboratory).

- Body mass index (BMI) ≥5th and ≤ 95th percentile as per CDC growth charts.

- The parent or guardian is willing and able to provide a signed and dated written
informed consent form prior to any study related procedures. When appropriate, the
participant has signed an assent to participate according to local IRB guidelines.

- The participants and/or participant's parents are able to understand and comply with
protocol requirements, instructions, and protocol-stated restrictions such that the
participant is likely to complete the study as planned.

- Based on the opinion of the physicians providing patient care and those conducting
the study, there are no apparent contraindications for inclusion as a participant in
a pharmacokinetic study.

- For the Pharmacokinetic Study (Arm 1):

- Participant is ≥ 2 years and ≤ 5 years of age.

- The participant is able to consume a minimum of 30 ml of water following ingestion of
the study article.

- For the Relative Bioavailability Study:

- Participant is > 5 years and < 17 years of age.

- All females of child-bearing potential must be found to have a negative serum
pregnancy test prior to initial dosing and be willing to practice appropriate
contraceptive measures, including abstinence, from the time of the initial pregnancy
testing through the remainder of the study (30 days after last administration of
investigational agents).

- The participant is able to ingest both capsule and liquid study articles and consume
a minimum of 30 ml of water following ingestion of medication.

EXCLUSION CRITERIA

- A participant will not be eligible for inclusion in this study if any of the
following criteria apply:

- Chronic transfusion therapy, or transfused within 3 months of study participation.

- Known renal impairment (creatinine greater than 1.5 times the upper limit of normal
for age in the screening laboratory).

- Known hepatic impairment or elevated transaminases (greater than 3 times normal).

- Known presence of malignancy.

- The participant is unwilling and/or unable to abstain from use of tobacco- or
nicotine-containing products for 24 hours prior to screening and for 24 hours prior
to dosing until collection of the final PK sample during each treatment period.

- Diagnoses other than sickle cell anemia or sickle beta-zero thalassemia (i.e., other
sickle cell variants or sickle hereditary persistence of fetal hemoglobin).

- Blood count parameters as follows: Hemoglobin less than 6.0 gm/dL, absolute
reticulocyte count less than 80,000 mm-3, neutrophil count less than 1200 mm-3,
platelet count less than 150,000 mm-3.

- The participant has used opiates, H2 blockers, proton pump inhibitors, antacids,
other GI motility agents or any other medication that, in the opinion of the
investigator and/or sponsor, will interfere with the study procedures or affect the
interpretation of the results of the study for 3 days prior to the first dose of
study.

- Use of over the counter non-steroidal anti-inflammatory agent or narcotic analgesic
within 3 days.

- Participant has received an investigational drug within the past 30 days.

- Use of any illicit or illegal substances.

- The parent or guardian is unwilling or unable to provide a signed and dated written
informed consent form prior to any study related procedures, or, when appropriate,
the participant has refused to sign an assent to participate according to local IRB
guidelines.

- Any other condition or chronic illness, which in the opinion of the Principal
Investigator makes participation unadvised or unsafe.

- The caregiver is unwilling or unable to provide a completed study diary for a
participant in the steady-state subset.