The Food and Drug Administration has granted accelerated approval to voxelotor (Oxbryta) to treat sickle cell disease in children ages four to 11 years. Voxelotor previously received accelerated approval for this indication in people ages 12 years and older (see Drug Watch, March 2020). Accelerated approval is based on the expectation that the drug is likely to produce a clinical benefit; further clinical trials are required to verify this benefit.

Voxelotor is a hemoglobin S polymerization inhibitor that binds to hemoglobin S and increases the affinity of hemoglobin for oxygen. In sickle cell anemia, mutated hemoglobin forms polymers in red blood cells, creating the curved, or sickled, shape in response to deoxygenation of the red blood cells. Voxelotor prevents red blood cells from forming the sickle and restores their normal shape, reducing tissue and red blood cell damage. It is available as a tablet and as a tablet for oral suspension.

The effectiveness and safety of voxelotor in this population was determined in a phase 2 trial of 45 patients ages four to 11 years with sickle cell disease. Evaluation was based on whether hemoglobin levels rose more than 1 gram per deciliter; 36% of patients experienced this increase.

The most common adverse effects of voxelotor in children are similar to those in adolescents and adults, and include headache, vomiting, diarrhea, abdominal pain, nausea, rash, and fever. Hypersensitivity reactions are possible, but not common.

Nurses should weigh children prescribed voxelotor, as the dose is weight dependent. Voxelotor has the potential for drug interactions via the cytochrome P-450 (CYP) isoenzyme system, as its metabolism is mediated via several enzymes, notably CYP3A4. Nurses should use a drug database to check if coprescribed medications are either strong or moderate CYP3A4 inducers or sensitive CYP3A4 substrates.

Nurses should teach parents or caregivers that regular tablets should be swallowed whole, but tablets for oral suspension should be mixed with room temperature clear fluid immediately before drinking it. Tablets for oral suspension should not be swallowed whole, cut, crushed, or chewed.

For complete prescribing information for voxelotor, go to http://www.accessdata.fda.gov/drugsatfda_docs/label/2021/213137s006lbl.pdf.