Voxelotor
OXBRYTA
What it isVoxelotor is an oral hemoglobin S polymerization inhibitor that increases hemoglobin's oxygen affinity to reduce red-cell sickling.
Why this oneMarketed as Oxbryta, it was approved to raise hemoglobin levels in patients with sickle cell disease.
What limits itPfizer voluntarily withdrew it from worldwide markets in September 2024 after data suggested increased vaso-occlusive crises and deaths.
FDA label
Read the full label on DailyMed ↗
| FDA dosing | Population | Start | Target | Max |
|---|---|---|---|---|
| Sickle cell disease | adults & peds >=12 y | 1,500 mg QD | 1,500 mg QD | 1,500 mg QD (2,500 mg QD only if unavoidable strong CYP3A4 inducer; 2,000 mg QD if moderate inducer) |
| Sickle cell disease | peds 4 to <12 y, >=40 kg | 1,500 mg QD | 1,500 mg QD | 1,500 mg QD |
| Sickle cell disease | peds 4 to <12 y, 20 to <40 kg | 900 mg QD | 900 mg QD | 900 mg QD |
| Sickle cell disease | peds 4 to <12 y, 10 to <20 kg | 600 mg QD | 600 mg QD | 600 mg QD |
Renal Undefined
Hepatic Mild/moderate: no adjustment. Severe (Child-Pugh C): 1,000 mg QD (adults & >=12 y); peds 4-<12 y: reduce by weight (>=40 kg 1,000 or 900 mg; 20-<40 kg 600 mg; 10-<20 kg 300 mg) QD
Instructions
- Take with or without food; may be given with or without hydroxyurea
- Tablets: swallow whole — do not cut, crush, or chew
- Tablets for oral suspension: disperse in room-temperature clear liquid immediately before use (do not swallow whole); swirl, wait 1-5 min, swirl and drink; resuspend residue and repeat
- Missed/incomplete dose: skip and resume next day
- Avoid strong/moderate CYP3A4 inducers; if unavoidable, increase dose (adults/>=12 y: 2,500 mg QD strong, 2,000 mg QD moderate; peds per weight table)
Cautions
- Serious hypersensitivity reactions (<1%), incl. DRESS (postmarketing) — discontinue and do not reinitiate
- Interferes with HPLC quantification of Hb species (HbA/HbS/HbF) — measure only after >=10 days off drug
Adverse reactions
- Adults/>=12 y: headache, diarrhea, abdominal pain, nausea, rash, pyrexia (>=10%, >3% vs placebo)
- Peds 4-<12 y: pyrexia, vomiting, rash, abdominal pain, diarrhea, headache (>10%)
- Postmarketing: DRESS, pruritus, angioedema
Pregnancy No human data; SCD itself raises maternal/fetal risk; use only if benefit outweighs risk
Lactation Breastfeeding NOT recommended during treatment and for 2 weeks after last dose (potential serious hematopoietic effects in infant)
NO BOXED WARNINGS
Principal riskNo FDA boxed warning; withdrawn from the market in 2024 over increased vaso-occlusive crises and deaths.
Cost, est. cash$2,000–$15,000/month
Generic entry2037 est.
Classes and tags
Clinical profile
Legacy pregnancy categoryNot assigned — PLLR-era drug
Defining liabilityGenerally tolerated at therapeutic doses; clinically important risks are agent-specific and increase with interactions or organ impairment.
Mechanism of action: Voxelotor ballicule
