What is Hydroxyurea (HU)

Hydroxyurea (HU) is an anti-neoplastic agent that stimulates increased synthesis of fetal hemoglobin (Hb-F).  Hydroxyurea  is the generic drug name for this medication.  Droxia ™ and Hydrea™ are common brand names of hydroxyurea.  It was originally available in a pink and purple oval capsule form for adults but now it is available in a white rounded tablet form.  This tablet can be crushed into a suspension and administered to kids.
The synthesis of this wonder drug was initially performed in

Chemical Structure

1869 in Germany by Dressler and Stein.  It was first approved by the FDA in 1967 for the treatment of neoplastic diseases.  Results from the multicenter study for hydroxurea (MSH) prompted the FDA in 1998 to officially approved HU for use in treatment of adults with sickle cell disorder.  Before it was approved for treatment of sickle cell, hydroxurea had long been approved for the treatment of inoperable ovarian cancer, melanoma and chronic myelocytic leukemia (cancer of the white blood cells) as well.  Currently, it is prescribed as a form of treatment for people suffering from the vasocculsive symptoms and painful crisis associated with sickle cell disease (SCD).
HU is underutilized in the United States because of both patient and provider concern about its long term effect as well as future cancer complications. Even though HU is very beneficial in treating sickle cell disease.  There are some adverse effects associated with its uses.  Some of these side effects include: Harm to the unborn fetus if HU is administered during pregnancy.  Due to its cytotoxic nature, it is argued that a life time dependency on hydroxyurea could lead to other health complications like cancer.  On the contrary, hydroxyurea is an in-situ drug, meaning that it only works if present in the system.  Therefore, if administration of HU is stopped due to medical reasons and the body metabolises all the residuals, the effects of the drug ceases until a new dose is administered.
Recap: Hydroxyurea is a commonly used cytotoxic agent approved by the Food and Drug Administration for the treatment of SCD.  Sickle cell disease cannot be cured due to its genetic characteristics however hydroxyurea  induces high levels of fetal hemoglobin when administered to SCD patients and this helps reduce the frequency of pain episodes observed in sickle cell patients.  According to the results of the MSH study that looked at the effects of HU as a treatment option for sickle cell disease, it was found that HU reduced the frequency of vaso-occulsive crisis by approximately 50%.

References:
Charache S, Terrin M.L, Moore R.D, Dover G.J, Barton F.B, Eckert S.V, McMahon R.P & Bonds D.R. 1995. Effect of hydroxyurea on the frequency of painful crises in sickle cell anemia. Investigators of the Multicenter Study of Hydroxyurea in Sickle Cell Anemia. N Engl J Med 332: 1317 – 1322.
Balinga SB, Pace BS, Chen H, Arvind S, Yang Y. 2000. Mechanism for Fetal Hemoglobin Induction by Hydroxyurea in Sickle Cell Erythroid Progenitors. American Journal of Hematology 65:227-233.
Platt. O. S (2008): Hydroxyurea for the Treatment of Sickle Cell Anemia. New England Journal Medicine. 358(13): 1362- 1369.
Yang Y, Pace B, Kitchens D, Ballas SK, Arvind S, Baliga SB.1997. BFU-E Colony in Response to Hydroxyurea: Correlation between In-Vitro and In Vivo Fetal Hemoglobin Induction. American Journal of Hematology 56:252-258.
American Society of Health-System Pharmacists (ASHP 2008)
http://www.nih.gov/news/health/feb2008/od-27.htm (Medline 2008)