Siklos, Hydroxyurea-based Treatment for Pediatric SCD, Available in 100 mg Scored Tablets

Siklos (hydroxyurea)  — indicated for the treatment of children 2 and older with sickle cell disease — is now available in 100 mg scored tablets, in addition to the 1,000 mg triple-scored tablet form.

Scored tablets make measuring medicine more flexible, giving patients greater control in finding their own optimal dose. The “scores” on scored tablets mark where a patient can break them into smaller, pre-defined amounts.

Previously, the medicine was available as 100 mg tablets not designed for splitting, and as 1,000 mg tablets that could be split into four parts (250 mg each), meaning that doses were rounded to the nearest 100 mg.

With the new 100 mg scored tablet, which can be split into two 50 mg parts, doses can be calculated to the nearest 50 mg, allowing for more accurate weight-based dosing, and for smaller dose increments as weight increases.

This flexibility is particularly useful among pediatric patients, whose weight changes relatively quickly.

“With the newly available Siklos 100 mg scored tablets, dose adjustments can now be made in 50 mg increments. Coupled with Siklos 1,000 mg triple-scored tablets (4 x 250 mg), this will offer more accurate dose adjustments and may make it more convenient than compounded hydroxyurea,” Tanya Carro, said in a press release. Carro is general manager of Medunik USA, the company marketing Siklos. 

Siklos is a once-daily medication used to reduce the frequency of sickle cell crises — also called vaso-occlusive crises (VOC) — and the need for blood transfusions in children with recurrent moderate-to-severe crises.

These crises can be extremely painful and are considered medical emergencies. Siklos is believed to benefit SCD patients through a variety of mechanisms, the most important being an increase in fetal hemoglobin levels in the blood, which raises the amount of oxygen carried by red blood cells.

The medication also reduces the number of neutrophils, a type of immune cell that interacts with the sickled red blood cells to clog capillaries, resulting in the pain felt during crises.

Siklos is recommended at an initial daily dose of 20 mg per kg of body weight, and may be increased by 5 mg/kg every eight weeks, or as soon as a VOC episode occurs.

The medication can be dissolved in water, making it easier for patients who have trouble swallowing tablets. Medunik USA expects this to help patients not miss their dose of medicine.

The compound was the first — and so far only — pediatric hydroxyurea product approved in the United States. It also is widely available in Europe.

Because it lowers certain blood cell counts, Siklos carries the risk of making patients more prone to infection and to certain cancers and comes with a box warning to that effect. A healthcare provider should check a patient’s blood cell counts before using Siklos and every two weeks thereafter.

Finally, Siklos is associated with fertility problems in males, and females who become pregnant while taking it should consult their physician, as there is some risk to the fetus.