This study will investigate the safety, tolerability and potential for the use of up to three daily doses of 30-40 mg/kg HU (daily) upon hospitalization for painful vaso-occlusive crises .

Sickle cell anemia (SCA) is a hereditary hemoglobinopathy; complications of the disease include, spleen enlargement, acute chest syndrome, pulmonary hypertension, stroke and cumulative damage to multiple organs, and painful vaso-occlusive crises (VOC). In Brazil, about 3,500 children are born each year with DF, and the number of individuals with sickle cell disease (DF) in the country is estimated between 25,000 and 30,000 (ANVISA 2012; BRAZIL, 2012).

Hydroxyurea (HU, or hydroxycarbamide) is the only drug approved to date by the American FDA for use in adults with sickle cell disease. The drug modifies the disease process, improving hematological parameters and the hospitalization time of patients, as well as the frequency of vaso-occlusive crises.In addition to its proven effects during chronic use, experimental data indicate that HU has immediate anti-inflammatory effects.

In addition to its proven effects during chronic use, experimental data indicate that HU has immediate anti-inflammatory effects. This study will investigate the safety, tolerability and potential for the use of up to three daily doses of 30-40 mg/kg HU (daily) upon hospitalization for VOC.

Inclusion Criteria:

• Confirmed diagnosis of homozygous sickle cell anemia (HbSS).
• Hospitalization due to onset of uncomplicated vaso-occlusive crisis (with pain scale≥6 within the last 24 h), confirmed by clinical evaluation.
• Documented and written informed consent

Exclusion Criteria:

• Confirmed or suspected pregnancy.
• Initiation of painful crisis> 72h.
• Blood transfusion during the last 8 weeks.
• Admission to Emergency Room due to pain in the last 4 weeks.
• Neutrophil count <2.5 x 109/L or platelet count <95.0 x 109 / L or Hb <4.5 g / dL
• Weight <38 Kg or> 95 Kg.
• Interval longer than 8h since arrival at center.
• Non-consent to participate in the study.