Hydreasyn (Hydroxycarbamide)

Hydreasyn is indicated for several hematologic conditions where reduction of abnormal cell proliferation is required. It is prescribed as part of disease‑specific treatment protocols to control blood cell counts and disease progression.

• Chronic myelogenous leukemia (CML) to inhibit leukemic cell growth.
• Sickle cell disease to reduce frequency of painful crises.
• Polycythemia vera to lower elevated red blood cell mass.
• Essential thrombocythemia to control excessive platelet production.
• Certain myeloproliferative neoplasms when alternative therapy is unsuitable.

• Hydroxycarbamide exerts its antineoplastic effect by inhibiting the enzyme ribonucleotide reductase, which is essential for the conversion of ribonucleotides to deoxyribonucleotides. This inhibition decreases the intracellular pool of deoxyribonucleotides, limiting DNA synthesis and repair. As a result, rapidly dividing cells, such as malignant leukocytes and abnormal hematopoietic progenitors, experience cell‑cycle arrest, particularly in the S‑phase, leading to reduced proliferation. The drug’s effect is dose‑dependent and reversible upon discontinuation.

Hydroxycarbamide may cause a range of adverse reactions, varying from mild to severe.

Common

• Nausea or vomiting, especially at treatment initiation.
• Mild gastrointestinal upset, including abdominal pain or diarrhea.
• Transient skin discoloration or hyperpigmentation.
• Decreased white blood cell count (leukopenia) with mild infection risk.
• Fatigue or weakness, often mild to moderate.
• Mild hair loss (alopecia) in some patients.
• Mouth sores (stomatitis) that may cause discomfort.

Serious

• Severe bone marrow suppression leading to pancytopenia.
• Acute hemolytic anemia, particularly in patients with G6PD deficiency.
• Rare but serious liver toxicity manifesting as elevated transaminases.
• Severe allergic reactions such as Stevens‑Johnson syndrome.

When prescribing Hydreasyn, clinicians should evaluate patient-specific factors and monitor for potential complications throughout therapy.

• Baseline complete blood count (CBC) and periodic monitoring during treatment.
• Assess renal and hepatic function before initiation and adjust dose if impairment is present.
• Use caution in pregnant or breastfeeding women; benefits must outweigh potential risks.
• Avoid use in patients with known G6PD deficiency due to risk of hemolysis.
• Review concomitant medications that may exacerbate myelosuppression.
• Counsel patients on signs of infection and when to seek medical attention.

Hydroxycarbamide can alter the activity of several drugs; awareness of interactions helps prevent adverse outcomes.

Avoid

• Concurrent use with strong myelosuppressive agents (e.g., cytarabine, azacitidine) may cause profound bone‑marrow toxicity.
• Co‑administration with high‑dose allopurinol can increase hydroxycarbamide plasma levels and toxicity risk.
• Avoid simultaneous use with other ribonucleotide reductase inhibitors, as additive toxicity may occur.

Use with caution

• Anticoagulants (warfarin, direct oral anticoagulants) may have enhanced effect; monitor coagulation parameters.
• Live vaccines should be avoided due to immunosuppression; consider inactivated vaccines only.
• Drugs affecting renal excretion (e.g., NSAIDs, ACE inhibitors) may require dose adjustment and renal monitoring.
• Concurrent use of hydroxycarbamide with drugs that cause hepatic enzyme induction (e.g., rifampin) may reduce its efficacy.