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Drug

Hydroxyurea

Established medicine
ClassRibonucleoside-diphosphate reductase RR1 inhibitorResearchOngoing clinical research
Also known as Carbamohydroxamic acid, Carbamohydroximic acid, Carbamoyl oxime, Carbamyl hydroxamate+14 more

Carbamohydroxamic acid, Carbamohydroximic acid, Carbamoyl oxime, Carbamyl hydroxamate, Droxia, Hidroxicarbamida, Hydrea, Hydroxycarbamid, Hydroxycarbamide, Hydroxycarbamidum, Hydroxyharnstoff, Mylocel, N-Carbamoylhydroxylamine, N-Hydroxyurea, Oxyurea, Siklos, Xromi, Hydroxy Urea.

RxNorm5552ChEMBLCHEMBL467ATCL01XX05UNIIX6Q56QN5QC
6
Research papers
26
Active clinical trials
3
Protein targets
1
Regulatory events
Latest activity
beta

Recent clinical, regulatory, research and industry developments relating to this drug.

Pharmacokinetics, Efficacy and Safety of Twice Daily Dosing Regimen of Hydroxycarbamide Dispersible Tablets in Children With Sickle Cell Disease: a Single-group, Non-randomised, Open-label Study (KID-BID)

Clinical trial2026-10-01Results expected Q1 2028 · ClinicalTrials.gov

A Phase 2 Open-label Study to Evaluate the Activity of Etavopivat on Transcranial Doppler Velocities in Pediatric Patients With Sickle Cell Disease Who Are at Increased Risk for Primary Stroke

Clinical trial2026-09-10Results expected Q3 2027 · ClinicalTrials.gov

BrUOG 419 - Promoting Utilization and Safety of Hydroxyurea Using Precision in Africa (PUSHUP)

Clinical trial2026-09-01Primary completion · ClinicalTrials.gov

A Phase 3, Randomized, Double-blind, Active-Comparator-Controlled Clinical Study to Evaluate the Efficacy and Safety of Bomedemstat (MK-3543) Versus Hydroxyurea in Cytoreductive Therapy Naïve Essential Thrombocythemia Participants

Clinical trial2026-08-27Status changed to Active, not recruiting · ClinicalTrials.gov

A Phase 1 Study of OTS-412 (Recombinant Oncolytic Vaccinia Virus) in Combination With Hydroxyurea or Hydroxyurea/Atezolizumab in Treatment-refractory Solid Tumor Patients

Clinical trial2026-08-26Results expected Q4 2028 · ClinicalTrials.gov

A Randomized Phase 2 Study of Pacritinib vs. Hydroxyurea in Patients With Advanced Proliferative Chronic Myelomonocytic Leukemia

Clinical trial2026-08-18Results expected Q3 2028 · ClinicalTrials.gov

CD83 CAR T in Relapsed or Refractory Acute Myeloid Leukemia (AML): A Phase I Trial

Clinical trial2026-08-17Results expected Q2 2028 · ClinicalTrials.gov

Leukemic transformation and second cancers in 3649 patients with high-risk essential thrombocythemia in the EXELS study.

Research2018-10-11Leukemia research

Novel use Of Hydroxyurea in an African Region with Malaria (NOHARM): a trial for children with sickle cell anemia.

Research2017-10-19Blood

Hydroxycarbamide in very young children with sickle-cell anaemia: a multicentre, randomised, controlled trial (BABY HUG).

Research2011-05-01Lancet (London, England)

Recruitment of infants with sickle cell anemia to a Phase III trial: data from the BABY HUG study.

Research2010-08-24Contemporary clinical trials

Marketing authorisation: Siklos (EMA)

Regulatory2007-06-29EMA

Profile

Identifiers & mechanism

Canonical identifiers, marketed brand names and mechanism, resolved across RxNorm, ChEMBL and ATC.

Canonical name
Hydroxyurea
Aliases & brands
Carbamohydroxamic acidCarbamohydroximic acidCarbamoyl oximeCarbamyl hydroxamateDroxiaHidroxicarbamidaHydreaHydroxycarbamidHydroxycarbamideHydroxycarbamidumHydroxyharnstoffMylocelN-CarbamoylhydroxylamineN-HydroxyureaOxyureaSiklosXromiHydroxy Urea
RxNorm CUI
5552
ChEMBL ID
CHEMBL467
ATC codes
L01XX05
UNII
X6Q56QN5QC
Primary mechanism
Ribonucleoside-diphosphate reductase RR1 inhibitor
Regulatory jurisdictions
ema

Pharmacology & targets

3 targets

Known molecular targets and mechanisms supported by curated pharmacology databases.

Ribonucleoside-diphosphate reductase large subunit
RRM1 · P23921
INHIBITORRibonucleoside-diphosphate reductase RR1 inhibitor
Ribonucleoside-diphosphate reductase subunit M2 B
RRM2B · Q7LG56
INHIBITORRibonucleoside-diphosphate reductase RR1 inhibitor
Ribonucleoside-diphosphate reductase subunit M2
RRM2 · P31350
INHIBITORRibonucleoside-diphosphate reductase RR1 inhibitor

Regulatory timeline

1 event

The complete regulatory record, grouped by authority — approvals, safety advisories and label changes. Each authority shows its most recent events; expand one to read its full history.

Earliest approval
2007-06-29
Latest approval
2007-06-29
Authorities
EMA
Total events
1
emaEuropean Medicines Agency· 1 event
2007-06-29Original application approval
Marketing authorisation: Siklos (EMA)
Indication: Siklos is indicated for the prevention of recurrent painful vaso-occlusive crises including acute chest syndrome in paediatric and adult patients suffering from symptomatic… Show full indication

Siklos is indicated for the prevention of recurrent painful vaso-occlusive crises including acute chest syndrome in paediatric and adult patients suffering from symptomatic sickle-cell syndrome.

Evidence ↗

Contains information from the European Medicines Agency (European Medicines Agency), © EMA, reused under CC BY 4.0.

Clinical trials

168 trials

The current development programme across all trial phases — status mix, phase distribution and the late-stage studies shaping the evidence base.

Development programme
CLINICALTRIALS.GOV · LIVE REGISTRY
168
registered trials across all phases
LATEST COMPLETION 2026
26
Active studies
19
Recruiting
64
Late-stage (III+)
99
Completed
43
Discontinued
PHASE DISTRIBUTIONn = 168
Early Phase 13Phase 118Phase 1 / 215Phase 268Phase 2 / 34Phase 337Phase 49Phase N / A14

Late-stage studies

Phase III+ trials still open or recently active — where late-stage evidence is being generated.

Primary Prevention of Stroke in Children With SCD in Sub-Saharan Africa II: A Multicenter, Open-label, Single-arm Type I Hybrid Clinical Trial

RecruitingPH IVVanderbilt University Medical Centern=2202030

HU-F-AIM - A Prospective, Interventional Study to Evaluate HU-resistance in Polycythemia Vera Patients Who Meet Predictive Parameters Identified in the Machine Learning Project PV-AIM

TerminatedPH IVNovartis Pharmaceuticalsn=762026

Effects of Hydroxyurea and Metformin in Transfusion Dependent Beta-Thalassemia

CompletedPH IVBahria Universityn=962026

Efficacy of Combination of Hdroxyurea and Thalidomide Over Either Hydroxyurea or Thalidomide Alone in the Treatment of Transfusion Dependent Thalassemia in Children: A Quasi-Randomised Clinical Trial

CompletedPH IVBangabandhu Sheikh Mujib Medical University, Dhaka, Bangladeshn=902026

Risk Stratification for Clinical Severity of Sickle Cell Disease in Nigeria and Assessment of Efficacy and Safety During Treatment With Hydroxyurea

CompletedPH IVLoyola Universityn=532022

Recent completions

Trials that read out recently, adding to the completed evidence base.

Effects of Hydroxyurea and Metformin in Transfusion Dependent Beta-Thalassemia

CompletedPH IVBahria Universityn=962026

Efficacy of Combination of Hdroxyurea and Thalidomide Over Either Hydroxyurea or Thalidomide Alone in the Treatment of Transfusion Dependent Thalassemia in Children: A Quasi-Randomised Clinical Trial

CompletedPH IVBangabandhu Sheikh Mujib Medical University, Dhaka, Bangladeshn=902026

Hydroxyurea Optimization Through Precision Study (HOPS): A Prospective, Multi-center, Randomized Trial of Personalized, Pharmacokinetics-guided Dosing of Hydroxyurea Versus Standard Weight-based Dosing for Children With Sickle Cell Anemia.

CompletedPH IIILifespann=1042025

Hydroxyurea Therapy for Neurological and Cognitive Protection in Pediatric Sickle Cell Anemia in Uganda: A Single Arm Open Label Trial, "BRAIN SAFE II"

CompletedPH IIIGlobal Health Uganda LTDn=2702025

Assessing Combination Hydroxyurea and Exogenous Erythropoietin in Sickle Cell Disease

CompletedPH I/IIJulia Xun=172025

Reduced Intensity Conditioning for Haploidentical Bone Marrow Transplantation in Patients With Symptomatic Sickle Cell Disease. (BMTCTN1507)

CompletedPH IIMedical College of Wisconsinn=952025

Research activity

6 papers

Key research shaping understanding of this drug, combining the latest publications with the most influential evidence.

Publications over time
2010–2018
Most influential

Hydroxycarbamide in very young children with sickle-cell anaemia: a multicentre, randomised, controlled trial (BABY HUG).

Lancet (London, England) · 2011 · 592 cites

Novel use Of Hydroxyurea in an African Region with Malaria (NOHARM): a trial for children with sickle cell anemia.

Blood · 2017 · 128 cites

Adherence to study medication and visits: data from the BABY HUG trial.

Pediatric blood & cancer · 2010 · 35 cites

Recruitment of infants with sickle cell anemia to a Phase III trial: data from the BABY HUG study.

Contemporary clinical trials · 2010 · 34 cites

Urine concentrating ability in infants with sickle cell disease: baseline data from the phase III trial of hydroxyurea (BABY HUG).

Pediatric blood & cancer · 2010 · 20 cites

Leukemic transformation and second cancers in 3649 patients with high-risk essential thrombocythemia in the EXELS study.

Leukemia research · 2018 · 12 cites
Recent papers

Leukemic transformation and second cancers in 3649 patients with high-risk essential thrombocythemia in the EXELS study.

Leukemia research · 2018 · 12 cites

Novel use Of Hydroxyurea in an African Region with Malaria (NOHARM): a trial for children with sickle cell anemia.

Blood · 2017 · 128 cites

Hydroxycarbamide in very young children with sickle-cell anaemia: a multicentre, randomised, controlled trial (BABY HUG).

Lancet (London, England) · 2011 · 592 cites

Adherence to study medication and visits: data from the BABY HUG trial.

Pediatric blood & cancer · 2010 · 35 cites

Recruitment of infants with sickle cell anemia to a Phase III trial: data from the BABY HUG study.

Contemporary clinical trials · 2010 · 34 cites

Urine concentrating ability in infants with sickle cell disease: baseline data from the phase III trial of hydroxyurea (BABY HUG).

Pediatric blood & cancer · 2010 · 20 cites
Major research themes8
Hydroxyurea1Kidney Concentrating Ability1Leukemia, Myeloid, Acute1Neoplasms, Second Primary1Parents1Patient Compliance1Patient Dropouts1Patient Selection1
Journals, researchers & institutions
Top journals
  • Pediatric blood & cancer2
  • Blood1
  • Contemporary clinical trials1
  • Lancet (London, England)1
  • Leukemia research1
Leading researchers
  • Wang WC3
  • Ware RE3
  • Faughnan L2
  • Huang X2
  • Iyer RV2
  • Miller ST2
  • Rana S2
  • Rees RC2
Leading institutions
free-text, unnormalised
  • St Jude Children's Research Hospital2
  • Cincinnati Children's Hospital Medical Center1
  • Duke University Medical Center1
  • Guy's and St Thomas' NHS Foundation Trust1
  • Hospital del Mar-IMIM1
  • Institute for Medical Sciences1
References & data sources
  • RxNorm (U.S. National Library of Medicine) — drug identity
  • ChEMBL (EMBL-EBI) & UniProt — pharmacology and targets
  • Europe PMC — research literature
  • ClinicalTrials.gov — clinical trials
  • Regulatory event sources are credited in the Regulatory Timeline above.