Voxelotor

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.

• OXBRYTA is indicated for the treatment of sickle cell disease (SCD) in adults and pediatric patients 4 years of age and older. This indication is approved under accelerated approval based on increase in hemoglobin (Hb) [see Clinical Studies (14) ] .

• OXBRYTA is contraindicated in patients with a history of serious drug hypersensitivity reaction to voxelotor or excipients. Clinical manifestations may include generalized rash, urticaria, mild shortness of breath, mild facial swelling, and eosinophilia [see Warnings and Precautions (5.1) and Adverse Reactions (6.1) ].contraindicated

OXBRYTA can be taken with or without food. ( 2.7 ) Recommended dosage: • Adults and pediatric patients 12 years and older: 1,500 mg orally once daily. ( 2.1 ) • Pediatric patients 4 to less than 12 years: Dosing with OXBRYTA is based on body weight. See Table 1 for complete dosing recommendations. ( 2.2 ) Recommended dosage for severe hepatic impairment (Child Pugh C) : • Adults and pediatric patients 12 years and older: 1,000 mg orally once daily. ( 2.3 ) • Pediatric patients 4 to less than 12 years: Reduce the dose of OXBRYTA based on body weight. See Table 2 for complete dosing recommendations. ( 2.4 ) 2.1 Recommended Dosage for Adults and Pediatric Patients 12 Years and Older The recommended dosage of OXBRYTA is 1,500 mg orally once daily. 2.2 Recommended Dosage for Pediatric Patients 4 Years to Less Than 12 Years For pediatric patients 4 years to less than 12 years, select the appropriate product (OXBRYTA tablets or OXBRYTA tablets for oral suspension) based on patient's ability to swallow tablets and patient's weight. The recommended dosage of OXBRYTA for pediatric patients 4 years to less than 12 years is shown in Table 1.

• Hypersensitivity Reactions: Observe for signs and symptoms and manage promptly. ( 5.1 ) • Laboratory Test Interference: Perform quantification of hemoglobin species when patient is not receiving OXBRYTA. ( 5.2 ) 5.1 Hypersensitivity Reactions Serious hypersensitivity reactions after administration of OXBRYTA have occurred in <1% of patients treated. Clinical manifestations may include generalized rash, urticaria, mild shortness of breath, mild facial swelling, and eosinophilia [see Adverse Reactions (6.1) ] . Drug reaction with eosinophilia and systemic symptoms (DRESS) has been reported in postmarketing experience with OXBRYTA [see Adverse Reactions (6.2) ] . Patients who develop a combination of skin rash, fever, peripheral eosinophilia, and internal systemic organ involvement (e.g., hepatic, renal, pulmonary) while receiving OXBRYTA should undergo medical evaluation. Advise patients of the signs and symptoms of severe hypersensitivity reactions, including DRESS. If hypersensitivity reactions occur, discontinue OXBRYTA and administer appropriate medical therapy. Do not reinitiate OXBRYTA in patients who experience these symptoms with previous use. 5.2 Laboratory Test Interference OXBRYTA administration may interfere with measurement of Hb subtypes (HbA, HbS, and HbF) by high-performance liquid chromatography (HPLC) [see Drug Interactions (7.3) ]. If precise quantitation of Hb species is required, chromatography should be performed when the patient has not received OXBRYTA therapy in the immediately preceding 10 days.

The following clinically significant adverse reaction is discussed in other sections of the labeling: • Hypersensitivity Reactions [see Contraindications (4) and Warnings and Precautions (5.1) ]. Most common adverse reactions (incidence ≥10% with a difference of >3% compared to placebo) are headache, diarrhea, abdominal pain, nausea, rash, and pyrexia. ( 6.1 ) Most common adverse reactions (incidence >10%) reported in pediatric patients 4 to <12 years are pyrexia, vomiting, rash, abdominal pain, diarrhea, and headache. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Pfizer Inc. at 1-800-438-1985 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch . 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. Adults and Pediatric Patients 12 Years and Older The safety of OXBRYTA was evaluated in the HOPE trial based on data from 88 patients with SCD who received OXBRYTA 1,500 mg and 91 patients who received placebo orally once daily [see Clinical Studies (14.1) ] . Seventy-four patients received OXBRYTA 1,500 mg once daily for ≥24 weeks, 65 patients for ≥48 weeks, and 63 patients completed the 72-week treatment period. In patients who received OXBRYTA 1,500 mg once daily the median age was 24 years (range:12 to 59 years); 65% female; 66% Black or African American and 23% Arab/Middle Eastern; and 65% receiving hydroxyurea at baseline.

Lactation: Advise not to breastfeed. ( 8.2 ) 8.1 Pregnancy Risk Summary There are no available data on OXBRYTA use in pregnant women to evaluate for a drug-associated risk of major birth defects, miscarriage, or adverse maternal or fetal outcomes. In animal reproduction studies, oral administration of voxelotor to pregnant rats and rabbits during organogenesis at exposures up to 2.8-times (rats) and 0.3-times (rabbits) the exposure at the maximum recommended human dose resulted in no adverse developmental effects (see Data ). The estimated background risk of major birth defects and miscarriage for the indicated population is approximately 14% and up to 43%, respectively. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. There are adverse effects on maternal and fetal outcomes associated with SCD in pregnancy (see Clinical Considerations ). OXBRYTA should only be used during pregnancy if the benefit of the drug outweighs the potential risk. Clinical Considerations Disease-Associated Maternal and/or Embryo/Fetal Risk Women with SCD have an increased risk of adverse pregnancy outcomes for the mother and the fetus. Pregnant women are at greater risk for vasoocclusive crises, pre-eclampsia, eclampsia, and maternal mortality.

Metabolism

Voxelotor is absorbed into plasma and is then distributed predominantly into RBCs due to its preferential binding to Hb. The major route of elimination of voxelotor is by metabolism with subsequent excretion of metabolites into urine and feces.

• Nov 25, 2019NDANDA213137Global Blood Theraps
• Dec 17, 2021NDANDA216157Global Blood Theraps

1. 1Sickle Cell Anaemia With Crisis11,21650%
2. 2Product Dose Omission Issue5,17223%
3. 3Diarrhoea3,18714%
4. 4Off Label Use2,41611%
5. 5Nausea2,0169.0%
6. 6Headache1,6917.6%
7. 7Abdominal Pain Upper1,1715.3%
8. 8Pain1,0824.9%
9. 9Therapy Cessation1,0404.7%
10. 10Fatigue1,0074.5%
11. 11Abdominal Discomfort9694.3%
12. 12Therapy Interrupted9004.0%
13. 13Vomiting8333.7%
14. 14Haemoglobin Decreased7523.4%
15. 15Abdominal Pain6272.8%

The 10 most recently updated of 31 ClinicalTrials.gov registrations naming Voxelotor as an intervention. Registration is not evidence of efficacy or safety — reference crosswalk only.

• Study to Evaluate the Effect of GBT440 on TCD in Pediatrics With Sickle Cell Disease
  Terminated · Phase 3 · Interventional · 236 enrolled · Pfizer
  NCT04218084updated 2026-03-10
• Assessing Physical Function in Sickle Cell Patients Taking Voxelotor
  Active not recruiting · Phase 2 · Interventional · 6 enrolled · Inova Health Care Services
  NCT06023199updated 2026-02-02
• Oxbryta® Product Registry An Observational Study Designed to Evaluate the Effect of Oxbryta in Individuals With SCD
  Terminated · Observational · 265 enrolled · Pfizer
  NCT04930445updated 2025-12-31
• The Effect of Voxelotor on Cerebral Hemodynamic Response in Children With Sickle Cell Anemia
  Terminated · Phase 2 · Interventional · 22 enrolled · Emory University
  NCT05018728updated 2025-12-12
• Study to Assess the Effect of Long-term Treatment With Voxelotor in Participants Who Have Completed Treatment in Study GBT440-031
  Terminated · Phase 3 · Interventional · 179 enrolled · Pfizer
  NCT03573882updated 2025-11-18
• Open-Label Extension of Voxelotor
  Terminated · Phase 3 · Interventional · 162 enrolled · Pfizer
  NCT04188509updated 2025-11-13
• Study to Evaluate the Effect of GBT440 in Pediatrics With Sickle Cell Disease
  Terminated · Phase 2 · Interventional · 147 enrolled · Pfizer
  NCT02850406updated 2025-08-15
• Resolution of Sickle Cell Leg Ulcers With Voxelotor
  Terminated · Phase 3 · Interventional · 88 enrolled · Pfizer
  NCT05561140updated 2025-07-09
• A Voxelotor for Sickle Cell Anemia Patients at Highest Risk for Progression of Chronic Kidney Disease
  Terminated · Phase 1 · Phase 2 · Interventional · 12 enrolled · University of Illinois at Chicago
  NCT04335721updated 2025-04-03
• Voxelotor CYP and Transporter Cocktail Interaction Study
  Completed · Phase 1 · Interventional · 44 enrolled · Pfizer
  NCT05981365updated 2024-11-22

Frequently asked questions

How does Voxelotor work?

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.

What is Voxelotor used for?

According to FDA labeling, Voxelotor carries indications including: OXBRYTA is indicated for the treatment of sickle cell disease (SCD) in adults and pediatric patients 4 years of age and older. This indication is approved under accelerated approval based on increase in hemoglobin (Hb) [see Clinical Studies (14) ] .. This is a reference summary of labeled uses, not medical advice or a treatment recommendation.

What class of drug is Voxelotor?

Voxelotor is classified as Other hematological agents, Hemoglobin S Polymerization Inhibitor, Cytochrome P450 3A4 Inhibitors, Hemoglobin S Polymerization Inhibitors, Decreased Blood Viscosity, Increased Oxygen Carrying Capacity.

What are the brand names for Voxelotor?

Voxelotor is marketed under brand names including Oxbryta.

What are the contraindications for Voxelotor?

Voxelotor labeling lists contraindications including: OXBRYTA is contraindicated in patients with a history of serious drug hypersensitivity reaction to voxelotor or excipients. Clinical manifestations may include generalized rash, urticaria, mild shortness of breath, mild facial swelling, and eosinophilia [see Warnings and Precautions (5.1) and Adverse Reactions (6.1) ].. Always consult the full prescribing information and a clinician.