Hydroxyurea therapy for sickle cell disease

Sickle Cell Disease (SCD) affects many families in Ghana.

Two out of 100 newborns screened have SCD. Recently, some people living with the severest form of the disease in Ghana have been introduced to hydroxyurea or HU.

Hydroxyurea Therapy for SCD, HUT, is gaining popularity among children and adults with Sickle Cell Anaemia (those with the SS genotype), but it is still fairly new to many parents, patients and prescribers.

This therapy is very safe and effective for preventing severe expression of the disease, while improving the quality of life of persons on it.

The following are some of the questions asked frequently by parents and patients in the Sickle Cell Clinic with accompanying answers.

Questions

What is Hydroxyurea and how does it help persons with sickle cell anaemia?

Hydroxyurea (HU) is a medicine approved by the Food and Drugs Authority (FDA) of the USA for the treatment of Sickle Cell Anaemia, SCA (SCD-SS) in both children from the age of nine months and adults.

Although, not all patients with SS will benefit from HU, the benefits to even young children, as well as adults are so overwhelming that experts recommend its use in all children with SCD-SS genotype from the young age of nine months.

HU is a medication well-known for its use in the treatment of certain cancers.

Among patients with SCA (SS genotype) several large clinical trials have proved its safety and efficacy in reducing the frequency of: acute bone pain events (crises); blood transfusions; acute chest syndrome (chest pain with breathing difficulties) and hospitalisations.

Should my child show symptoms of severe disease before s/he can start the HU Therapy?

The answer is no. Treatment is initiated so that you do not experience the severe effects or complications of SCA. It prevents some of these complications; it does not reverse them.

What happens to the daily penicillin prophylaxis and folate supplementation?

Basically, SCD affects many bodily functions, including the body’s ability to fight deadly bacterial infections. Experts give children from two–to-three months of age with SCD penicillins in addition to routine vaccinations to protect them against pneumonia and meningitis-causing bacteria.

Hydroxyurea does not protect against these infections nor improve the immune function, hence penicillin prophylaxis will have to continue alongside daily HU therapy.

Daily folic acid supplementation supports the body’s blood factory (bone marrow) in producing new red blood cells to replace dead sickled cells which have short lifespans.

Think of it as provision of more raw materials for the factory to meet the body’s increased demand for more red cells.

How does HU work in people with Sickle Cell Anaemia?

SCD scientists have established the protective effects of haemoglobin F, HbF which is most abundant among foetuses and newborns.

Once its level reduces by four months of age, children with sickle cell disease start expressing symptoms. Hydroxyurea keeps the developmental switch for HbF production on to result in the beneficial effects together with other mechanisms.

When taken in appropriate doses over a period of time, HU will result in an increase in the F cells as well as in their HbF content, resulting in beneficial effects that will be described subsequently.

How is HU taken?

It is taken by mouth as a capsule or suspension for children. It is taken once every 24 hours (daily, at the same time).

Does HU work for everyone with SCD?

A small group of people may not derive the expected benefits of HUT after six months of adequate treatment.

What are the side effects of HU?

There is a potential for anaemia (excessive drop blood-level), bleeding (excessive decrease in platelets) and/or neutropenia (drop in white cell count) with increased risk of infection. These side effects are completely reversible once therapy is suspended.

All patients taking HU are strictly required to do regular blood tests to pre-empt these side effects.

Experts need to monitor patients closely to maintain the blood counts at levels where the most benefits are derived while being vigilant to avert any of the above side effects.

The writer is a Paediatric Oncologist of the Komfo Anokye Teaching Hospital (KATH)
E-mail: oseitutlaw@gmail.com