3 months ago
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Three weeks ago, I started discussing the various research available for newborns and young people living with sickle cell disease.
I decided to write about this because I was asked if there was hope of a cure for those living with SCD during an interview on World Sickle Cell Day.
There is hope, as medical researchers are working to advance treatments.
What is hydroxyurea?
Hydroxyurea: It is a medication commonly used to treat certain types of cancers and blood disorders, including sickle cell disease.
Chemical composition
Hydroxyurea is a small molecule with a specific chemical formula. It is available in oral form as capsules or tablets and is now also used for the management of sickle cell disease.
How does hydroxyurea work in sickle cell disease?
Hydroxyurea increases the production of fetal haemoglobin. Fetal haemoglobin is a type of haemoglobin that is normally present in fetuses and infants.
It does not form sickle shapes and helps prevent red blood cells from becoming deformed and sticking together.
Benefits of hydroxyurea in sickle cell disease
Reduction in vessel occlusive crises: It decreases the frequency and severity of painful episodes caused by blocked blood vessels.
Reduction in acute chest syndrome: This severe lung complication is less common in patients taking hydroxyurea.
Improved haematologic parameters: Hydroxyurea increases the overall haemoglobin level, reduces the number of sickle cells, and lowers the white blood cell count, which can reduce inflammation.
Fewer blood transfusions: Patients on hydroxyurea often require fewer blood transfusions.
Improved quality of life: By reducing pain and complications, hydroxyurea can significantly enhance the quality of life for individuals with SCD.
Dosage and administration
Initial dosing: The starting dose for hydroxyurea is typically based on body weight. It is gradually increased until the maximum tolerated dose is reached or until significant clinical benefits are observed.
Monitoring: Regular monitoring is essential, including blood counts and liver and kidney function tests, to ensure safe and effective dosage administration.
Side effects and risks
Common side effects: These can include nausea, vomiting, diarrhoea, loss of appetite, and skin changes.
Bone marrow suppression: Hydroxyurea can cause bone marrow suppression, leading to lower counts of white blood cells, red blood cells, and platelets. Regular blood tests are necessary to monitor these levels.
Risk of infection: Due to its immunosuppressive effects, patients may be at increased risk of infections.
Long-term risks: There is a potential risk of secondary malignancies with long-term use, though this risk is relatively low compared to its benefits in managing sickle cell disease.
Use in children and pregnant women
Children: Hydroxyurea is approved for use in children with sickle cell disease and has been shown to be safe and effective in reducing complications.
Pregnancy: Hydroxyurea is generally avoided during pregnancy due to potential teratogenic effects, which is a risk of causing birth defects. Women of childbearing age should use effective contraception while taking hydroxyurea.
Conclusion
Hydroxyurea is a crucial medication in the management of SCD, offering significant benefits in reducing pain and complications and improving overall quality of life.
While it does have side effects and requires careful monitoring, its role in increasing fetal haemoglobin production makes it a cornerstone of sickle cell treatment. Ongoing research continues to explore its long-term impact on patients.
Voxelotor
Voxelotor is an oral medication approved for the treatment of sickle cell disease. It works by increasing the affinity of haemoglobin for oxygen, thereby reducing the polymerisation of sickle cell haemoglobin (HbS) and the formation of sickle red blood cells.
What is voxelotor?
Chemical name: Voxelotor is also known by its chemical name, GBT440. Its brand name is Oxybryta. The US Food and Drug Administration approved Voxelotor for the treatment of sickle cell disease in November 2019.
Mechanism of action
Oxygen affinity: Voxelotor binds to haemoglobin and increases its affinity for oxygen. This altered haemoglobin-oxygen interaction stabilises haemoglobin in its oxygenated form.
Reduces polymerisation: By stabilising haemoglobin in its oxygenated state, voxelotor reduces the polymerisation of sickled haemoglobin. This helps prevent the formation of sickle-shaped red blood cells.
Improved red blood cell function: This stabilisation of haemoglobin prevents red blood cells from becoming deformed and sticky, which in turn reduces haemolysis (breakdown of red blood cells) and vaso-occlusive (blockage of red blood vessels).
Benefits of Voxelotor in sickle cell disease
Increased haemoglobin levels: Clinical trials have shown that voxelotor significantly increases haemoglobin levels in patients living with sickle cell disease, which can help alleviate anaemia.
Reduction in haemolysis: By reducing the breakdown of red blood cells, voxelotor decreases the level of markers associated with haemolysis.
Fewer pain episodes: Some studies suggest that voxelotor may reduce the frequency of painful vaso-occlusive crises, though its primary benefit is improving haemoglobin levels and reducing haemolysis.
Dosage and administration
The typical starting dose for voxelotor is 1500 mg taken orally once a day, with or without food.
Adjustments: Dosage adjustments may be necessary based on patient response and tolerance, as well as the presence of other medical conditions or medications.
Side effects and risks
Common side effects: These may include headaches, diarrhoea, fatigue, and rash.
Serious side effects: Although rare, voxelotor can cause serious side effects, including hypersensitivity reactions and elevated liver enzymes. Regular monitoring of liver function is recommended.
Drug interactions: Voxelotor can interact with other medications, particularly those that affect liver enzymes involved in drug metabolism.
Use in children: Voxelotor has been approved for use in children aged 12 years and older with sickle cell disease.
Pregnant and breastfeeding: The effects of voxelotor on pregnant and breastfeeding women have not been well studied. It should be used during pregnancy only if the potential benefit justifies the potential risks.
Conclusion
Voxelotor represents a significant advancement in the treatment of sickle cell disease. By targeting the underlying mechanism of sickle cell formation, it offers a novel approach to managing the disease, particularly in improving haemoglobin levels and reducing haemolysis. Its introduction provides patients with a new therapeutic option that can help manage symptoms and potentially improve quality of life.
Until next time
If you would like to get in touch with me about sickle cell, please do so via my email address: [email protected]. Also, check out my blog: https://www.dailylivingwithsicklecell.com/ and my book on sickle cell, HOW TO LIVE WITH SICKLE CELL, as well as my other books available for purchase on www.amazon.com.
