Hydroxyurea

Antimetabolite (Ribonucleotide Reductase Inhibitor)

Drug Class: Antimetabolite (Ribonucleotide Reductase Inhibitor)
Mechanism of Action (MOA): Inhibits ribonucleotide reductase (↓ DNA synthesis) and raises fetal hemoglobin (HbF), reducing sickling.
Black Box Warning: Myelosuppression and malignancy — can cause severe bone-marrow suppression and is carcinogenic.
Clinical Notes: Disease-modifying in sickle cell disease (↑ HbF → fewer pain crises and acute chest episodes); also myeloproliferative disorders. Monitor CBC; teratogenic.
Source: FDA label (DailyMed)