General Information

Oxbryta (voxelotor) is a hemoglobin S polymerization inhibitor.

Oxbryta is specifically indicated for the treatment of sickle cell disease in adults and children 4 years of age and older.

Oxbryta is supplied as tablets for oral administration. The recommended dose is 1,500 mg taken orally once daily with or without food. If a dose is missed, continue dosing on the day following the missed dose. Patients should swallow Oxbryta tablets whole. Do not cut, crush, or chew the tablets. Oxbryta may be given with or without hydroxyurea.

Mechanism of Action

Oxbryta (voxelotor) is a hemoglobin S (HbS) polymerization inhibitor that binds to HbS with a 1:1 stoichiometry and exhibits preferential partitioning to red blood cells (RBCs). By increasing the affinity of Hb for oxygen, voxelotor demonstrates dose-dependent inhibition of HbS polymerization. Nonclinical studies suggest that voxelotor may inhibit RBC sickling, improve RBC deformability, and reduce whole blood viscosity.

Side Effects

Adverse effects associated with the use of Oxbryta may include, but are not limited to, the following:

• headache
• diarrhea
• abdominal pain
• nausea
• fatigue
• rash
• pyrexia

Clinical Trial Results

The FDA approval of Oxbryta was based on the Phase 3 HOPE (Hemoglobin Oxygen Affinity Modulation to Inhibit HbS PolymErization) Study which enrolled 274 patients 12 years of age and older with SCD who were randomized to daily oral administration of Oxbryta 1,500 mg, Oxbryta 900 mg or placebo. Data showed that, after 24 weeks of treatment, 51.1% of patients receiving Oxbryta achieved a greater than 1 g/dL increase in hemoglobin compared with 6.5% receiving placebo.