Warnings for Hydrea
Included as part of the "PRECAUTIONS" Section
Precautions for Hydrea
Myelosuppression
Hydroxyurea causes severe myelosuppression. Treatment with hydroxyurea should not be initiated if bone marrow function is markedly depressed. Bone marrow suppression may occur, and leukopenia is generally its first and most common manifestation. Thrombocytopenia and anemia occur less often and are seldomseen without a preceding leukopenia. Bone marrow depression is more likely in patients who have previously received radiotherapy or cytotoxic cancer chemotherapeutic agents; use hydroxyurea cautiously in such patients.
Evaluate hematologic status prior to and during treatment with HYDREA. Provide supportive care and modify dose or discontinue HYDREA as needed. Recovery frommyelosuppression is usually rapid when therapy is interrupted.
Malignancies
Hydroxyurea is a human carcinogen. In patients receiving long-termhydroxyurea for myeloproliferative disorders, secondary leukemia has been reported. Skin cancer has also been reported in patients receiving long-termhydroxyurea. Advise protection fromsun exposure and monitor for the development of secondary malignancies.
Embryo-Fetal Toxicity
Based on the mechanismof action and findings in animals, HYDREA can cause fetal harmwhen administered to a pregnant woman. Hydroxyurea was embryotoxic and teratogenic in rats and rabbits at doses 0.8 times and 0.3 times, respectively, the maximumrecommended human daily dose on a mg/m2 basis. Advise pregnant women of the potential risk to a fetus [see Use In Specific Populations].
Advise females of reproductive potential to use effective contraception during and after treatment with HYDREA for at least 6 months after therapy. Advise males of reproductive potential to use effective contraception during and after treatment with HYDREA for at least 1 year after therapy [see Use In Specific Populations].
Vasculitic Toxicities
Cutaneous vasculitic toxicities, including vasculitic ulcerations and gangrene, have occurred in patients with myeloproliferative disorders during therapy with hydroxyurea. These vasculitic toxicities were reported most often in patients with a history of, or currently receiving, interferon therapy. If cutaneous vasculitic ulcers occur, institute treatment and discontinue HYDREA.
Live Vaccinations
Avoid use of live vaccine in patients taking HYDREA. Concomitant use of HYDREA with a live virus vaccine may potentiate the replication of the virus and/or may increase the adverse reaction of the vaccine because normal defense mechanisms may be suppressed by HYDREA. Vaccination with live vaccines in a patient receiving HYDREA may result in severe infection. Patient’s antibody response to vaccines may be decreased. Consider consultation with a specialist.
Risks With Concomitant Use Of Antiretroviral Drugs
Pancreatitis, hepatotoxicity, and peripheral neuropathy have occurred when hydroxyurea was administered concomitantly with antiretroviral drugs, including didanosine and stavudine [see DRUG INTERACTIONS].
Radiation Recall
Patients who have received irradiation therapy in the past may have an exacerbation of post-irradiation erythema. Monitor for skin erythema in patients who previously received radiation and manage symptomatically.
Macrocytosis
HYDREA may cause macrocytosis, which is self-limiting, and is often seen early in the course of treatment. The morphologic change resembles pernicious anemia, but is not related to vitamin B12 or folic acid deficiency. This may mask the diagnosis of pernicious anemia. Prophylactic administration of folic acid is recommended.
Pulmonary Toxicity
Interstitial lung disease including pulmonary fibrosis, lung infiltration, pneumonitis, and alveolitis/allergic alveolitis (including fatal cases) have been reported in patients treated for myeloproliferative neoplasm. Monitor patients developing pyrexia, cough, dyspnea, or other respiratory symptoms frequently, investigate and treat promptly. Discontinue HYDREA and manage with corticosteroids [see ADVERSE REACTIONS].
Laboratory Test Interference
Interference with Uric Acid, Urea, or Lactic Acid Assays is possible, rendering falsely elevated results of these in patients treated with hydroxyurea [see DRUG INTERACTIONS].
Nonclinical Toxicology
Carcinogenesis, Mutagenesis, Impairment Of Fertility
Conventional long-termstudies to evaluate the carcinogenic potential of hydroxyurea have not been performed. However, intraperitoneal administration of 125 to 250 mg/kg hydroxyurea (about 0.6-1.2 times the maximumrecommended human oral daily dose on a mg/m2 basis) thrice weekly for 6 months to female rats increased the incidence of mammary tumors in rats surviving to 18 months compared to control. Hydroxyurea is mutagenic in vitro to bacteria, fungi, protozoa, and mammalian cells. Hydroxyurea is clastogenic in vitro (hamster cells, human lymphoblasts) and in vivo (SCE assay in rodents, mouse micronucleus assay). Hydroxyurea causes the transformation of rodent embryo cells to a tumorigenic phenotype.
Hydroxyurea administered to male rats at 60 mg/kg/day (about 0.3 times the maximumrecommended human daily dose on a mg/m2 basis) produced testicular atrophy, decreased spermatogenesis, and significantly reduced their ability to impregnate females.
Use In Specific Populations
Pregnancy
Risk Summary
HYDREA can cause fetal harmbased on findings fromanimal studies and the drug’s mechanismof action [see CLINICAL PHARMACOLOGY]. There are no data with HYDREA use in pregnant women to informa drug-associated risk. In animal reproduction studies, administration of hydroxyurea to pregnant rats and rabbits during organogenesis produced embryotoxic and teratogenic effects at doses 0.8 times and 0.3 times, respectively, the maximumrecommended human daily dose on a mg/m2 basis (see Data). Advise women of the potential risk to a fetus and to avoid becoming pregnant while being treated with HYDREA.
In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2%–4% and 15%–20%, respectively.
Data
Animal Data
Hydroxyurea has been demonstrated to be a potent teratogen in a wide variety of animal models, including mice, hamsters, cats, miniature swine, dogs, and monkeys at doses within 1-fold of the human dose given on a mg/m2 basis. Hydroxyurea is embryotoxic and causes fetal malformations (partially ossified cranial bones, absence of eye sockets, hydrocephaly, bipartite sternebrae, missing lumbar vertebrae) at 180 mg/kg/day (about 0.8 times the maximumrecommended human daily dose on a mg/m2 basis) in rats and at 30 mg/kg/day (about 0.3 times the maximumrecommended human daily dose on a mg/m2 basis) in rabbits. Embryotoxicity was characterized by decreased fetal viability, reduced live litter sizes, and developmental delays. Hydroxyurea crosses the placenta. Single doses of ≥375 mg/kg (about 1.7 times the maximumrecommended human daily dose on a mg/m2 basis) to rats caused growth retardation and impaired learning ability.
Lactation
Risk Summary
Hydroxyurea is excreted in human milk. Because of the potential for serious adverse reactions in a breastfed infant fromhydroxyurea, including carcinogenicity, discontinue breastfeeding during treatment with HYDREA.
Females And Males Of Reproductive Potential
Pregnancy Testing
Verify the pregnancy status of females of reproductive potential prior to initiating HYDREA therapy.
Contraception
Females
HYDREA can cause fetal harmwhen administered to a pregnant woman [see Pregnancy]. Advise females of reproductive potential to use effective contraception during and after treatment with HYDREA for at least 6 months after therapy. Advise females to immediately report pregnancy.
Males
HYDREA may damage spermatozoa and testicular tissue, resulting in possible genetic abnormalities. Males with female sexual partners of reproductive potential should use effective contraception during and after treatment with HYDREA for at least 1 year after therapy [see Nonclinical Toxicology].
Infertility
Males
Based on findings in animals and humans, male fertility may be compromised by treatment with HYDREA. Azoospermia or oligospermia, sometimes reversible, has been observed in men. Informmale patients about the possibility of spermconservation before the start of therapy [see ADVERSE REACTIONS and Nonclinical Toxicology].
Pediatric Use
Safety and effectiveness in pediatric patients have not been established.
Geriatric Use
Elderly patients may be more sensitive to the effects of hydroxyurea and may require a lower dose regimen. Hydroxyurea is excreted by the kidney, and the risk of adverse reactions to this drug may be greater in patients with impaired renal function. Because elderly patients are more likely to have decreased renal function, care should be taken in dose selection, and it may be useful to monitor renal function [see DOSAGE AND ADMINISTRATION].
Renal Impairment
The exposure to hydroxyurea is higher in patients with creatinine clearance of less than 60 mL/min or in patients with end-stage renal disease (ESRD). Reduce dosage and closely monitor the hematologic parameters when HYDREA is to be administered to these patients [see DOSAGE AND ADMINISTRATION and CLINICAL PHARMACOLOGY].
Hepatic Impairment
There are no data that support specific guidance for dosage adjustment in patients with hepatic impairment. Close monitoring of hematologic parameters is advised in these patients.