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Pharma Intelligence, Simplified

Data updated: Mar 10, 2026

SIKLOS

HYDROXYUREA
Hematology Approved 2017-12-21
2
Indications
--
Phase 3 Trials
8
Years on Market

Details

Status
Prescription
First Approved
2017-12-21
Routes
ORAL
Dosage Forms
TABLET

Companies

Active Ingredient: HYDROXYUREA

SIKLOS Approval History

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What SIKLOS Treats

1 indications

SIKLOS is approved for 1 conditions since its original approval in 2017. These indications span multiple therapeutic areas including oncology, immunology, and more.

  • Sickle Cell Anemia
Source: FDA Label

SIKLOS Boxed Warning

MYELOSUPPRESSION and MALIGNANCIES WARNING: MYELOSUPPRESSION and MALIGNANCIES See full prescribing information for complete boxed warning . Myelosuppression : SIKLOS may cause severe myelosuppression. Do not give if bone marrow function is markedly depressed. Monitor blood counts at baseline and throughout treatment. Interrupt treatment and reduce dose as necessary. ( 5.1 ) Malignancies : Hydroxyurea is carcinogenic. Advise sun protection and monitor patients for malignancies. ( 5.2 ) Myelosuppre...

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Trial Timeline

Full development history with FDA approval milestones

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Understanding FDA Approval Types
Count Type What it means
- ORIG Original approval - drug first enters market
- SUPPL - Efficacy New indication (new disease/condition approved)
- SUPPL - Labeling Label text changes (warnings, dosing updates)
- SUPPL - Manufacturing Production changes (new facility)
- SUPPL - Chemistry Formulation changes (new dosage strength)

Green lines in the timeline show ORIG and Efficacy approvals - the clinically meaningful milestones.

SIKLOS FDA Label Details

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Indications & Usage

FDA Label (PDF)

SIKLOS ® is indicated to reduce the frequency of painful crises and to reduce the need for blood transfusions in adult and pediatric patients, 2 years of age and older, with sickle cell anemia with recurrent moderate to severe painful crises SIKLOS is an antimetabolite, indicated to reduce the frequency of painful crises and to reduce the need for blood transfusions in adult and pediatric patients, 2 years of age and older, with sickle cell anemia with recurrent moderate to severe painful crises.

⚠️ BOXED WARNING

WARNING: MYELOSUPPRESSION and MALIGNANCIES WARNING: MYELOSUPPRESSION and MALIGNANCIES See full prescribing information for complete boxed warning . Myelosuppression : SIKLOS may cause severe myelosuppression. Do not give if bone marrow function is markedly depressed. Monitor blood counts at baseline...

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Data Sources

Data sourced from official FDA and NIH databases. Click links to verify on original sources.