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Box 10 Prescribing guidelines for hydroxycarbamide

From: French guidelines for the etiological workup of eosinophilia and the management of hypereosinophilic syndromes

Hydroxycarbamide is administered orally at a daily dosage of 15–30 mg/kg (in one or two daily doses). Outside of emergency settings (where the starting dose is typically 1500–2000 mg daily), the standard practice for HES is to start with a low dosage (e.g., 1000 mg daily) and then increase it as needed depending on treatment effectiveness and tolerability. Hydroxycarbamide is contraindicated in patients with lactase deficiency, pregnancy and severe cytopenia (neutropenia < 10 × 109/L, thrombocytopenia < 100 × 109/L and/or anemia < 10 g/dL).

Because the risk of bone marrow failure is higher in patients who have received prior radiation or chemotherapy, hydroxycarbamide should be administered with caution in this situation. Likewise, in case of renal failure and/or concomitant use of other myelosuppressive agents, a reduction in the dosages of hydroxycarbamide and increased monitoring are recommended.

In case of significant HE, significant splenomegaly and/or elevated uric acid levels, hydration is recommended at the start of treatment to prevent the possible occurrence of lysis syndrome.

Regular (e.g., every two weeks for two months after initiation of treatment, and then every three months thereafter) clinical (including screening for oral or photo-induced lesions, trophic skin disorders, skin neoplasia and/or fibrosing lung disease that may be promoted by treatment) and laboratory monitoring (including CBC, serum electrolytes, urea, creatinine, transaminases, etc.) is indicated in long-term treatment. Hydroxycarbamide treatment is known to be associated with an increase of erythrocytes’ average globular volume of to up to 120 fL. Lastly, live attenuated vaccines are contraindicated in case of concomitant treatment with hydroxycarbamide.