Skip to Content


Dosage Form: capsule

Indications and Usage for Hydroxyurea

Hydroxyurea Capsules USP are indicated for the treatment of:

Resistant chronic myeloid leukemia.
Locally advanced squamous cell carcinomas of the head and neck (excluding the lip) in combination with chemoradiation.

Hydroxyurea Dosage and Administration

Dosing Information

Hydroxyurea is used alone or in conjunction with other antitumor agents or radiation therapy to treat neoplastic diseases. Individualize treatment based on tumor type, disease state, response to treatment, patient risk factors, and current clinical practice standards.

Base all dosage on the patient’s actual or ideal weight, whichever is less.

Hydroxyurea is a cytotoxic drug. Follow applicable special handling and disposal procedures [see References (15)].

Prophylactic administration of folic acid is recommended [see Warnings and Precautions (5.7)].

Dose Modifications for Toxicity

Monitor for the following and reduce the dose or discontinue Hydroxyurea accordingly:

Myelosuppression [see Warnings and Precautions (5.1)]
Cutaneous vasculitis [see Warnings and Precautions (5.4)]

Monitor blood counts at least once a week during Hydroxyurea therapy. Severe anemia must be corrected before initiating therapy with Hydroxyurea. Consider dose modifications for other toxicities.

Dose Modifications for Renal Impairment

Reduce the dose of Hydroxyurea by 50% in patients with measured creatinine clearance of less than 60 mL/min or with end-stage renal disease (ESRD) [see Use in Specific Populations (8.6) and Clinical Pharmacology (12.3)].

Creatinine Clearance


Recommended Hydroxyurea Initial Dose

(mg/kg daily)



<60 or ESRD*


* On dialysis days, administer Hydroxyurea to patients following hemodialysis.

Close monitoring of hematologic parameters is advised in these patients.

Dosage Forms and Strengths

Capsules: 500 mg purple opaque cap and pink opaque body imprinted in black ink barr 882.


Hydroxyurea is contraindicated in patients who have demonstrated a previous hypersensitivity to Hydroxyurea or any other component of the formulation.

Warnings and Precautions


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 seldom seen 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 Hydroxyurea. Provide supportive care and modify dose or discontinue Hydroxyurea as needed. Recovery from myelosuppression is usually rapid when therapy is interrupted.


Hydroxyurea is a human carcinogen. In patients receiving long-term Hydroxyurea for myeloproliferative disorders, secondary leukemia has been reported. Skin cancer has also been reported in patients receiving long-term Hydroxyurea. Advise protection from sun exposure and monitor for the development of secondary malignancies.

Embryo-Fetal Toxicity

Hydroxyurea may cause fetal harm when administered to a pregnant woman. Hydroxyurea is genotoxic. 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 at 180 mg/kg/day in rats and at 30 mg/kg/day in rabbits. Single doses of ≥375 mg/kg to rats caused growth retardation and impaired learning ability. Advise pregnant women of the potential risk to a fetus. Advise females of reproductive potential to use effective contraception during and after treatment with Hydroxyurea for at least 30 days after therapy. Females of reproductive potential should also ensure that their male partner, who is/has taken Hydroxyurea, uses effective contraception during and after treatment for at least 1 year after therapy. Advise males of reproductive potential to use effective contraception during and after treatment with Hydroxyurea for at least 1 year after therapy [see Use in Specific Populations (8.1, 8.3)].

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 of Hydroxyurea.

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 (7.1)].

Radiation Recall

Patients who have received irradiation therapy in the past may have an exacerbation of postirradiation erythema. Monitor for skin erythema in patients who previously received radiation and manage symptomatically.


Hydroxyurea 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.

Adverse Reactions

The following adverse reactions are described in detail in other labeling sections:

Myelosuppression [see Warnings and Precautions (5.1)]
Malignancies [see Warnings and Precautions (5.2)]
Embryo-fetal toxicity [see Warnings and Precautions (5.3)]
Vasculitic toxicities [see Warnings and Precautions (5.4)]
Risks with concomitant use of antiretroviral drugs [see Warnings and Precautions (5.5)]
Radiation recall [see Warnings and Precautions (5.6)]
Macrocytosis [see Warnings and Precautions (5.7)]

Postmarketing Experience

The following adverse reactions have been identified during postapproval use of Hydroxyurea. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency.

Gastrointestinal disorders: stomatitis, anorexia, nausea, vomiting, diarrhea, and constipation
Skin and subcutaneous tissue disorders: maculopapular rash, skin ulceration, dermatomyositis-like skin changes, peripheral and facial erythema, hyperpigmentation, atrophy of skin and nails, scaling, violet papules, and alopecia
Renal and urinary disorders: dysuria, elevations in serum uric acid, blood urea nitrogen (BUN), and creatinine levels
Nervous system disorders: headache, dizziness, drowsiness, disorientation, hallucinations, and convulsions
General Disorders: fever, chills, malaise, edema, and asthenia
Hepatobiliary disorders: elevation of hepatic enzymes
Respiratory disorders: diffuse pulmonary infiltrates, dyspnea, and pulmonary fibrosis

Adverse reactions observed with combined Hydroxyurea and irradiation therapy are similar to those reported with the use of Hydroxyurea or radiation treatment alone. These effects primarily include bone marrow depression (anemia and leukopenia), gastric irritation, and mucositis. Almost all patients receiving an adequate course of combined Hydroxyurea and irradiation therapy will demonstrate concurrent leukopenia. Platelet depression (<100,000 cells/mm3) has occurred in the presence of marked leukopenia. Hydroxyurea may potentiate some adverse reactions usually seen with irradiation alone, such as gastric distress and mucositis.

Drug Interactions

Increased Toxicity with Concomitant Use of Antiretroviral Drugs


In patients with HIV infection during therapy with Hydroxyurea and didanosine, with or without stavudine, fatal and nonfatal pancreatitis have occurred. Hydroxyurea is not indicated for the treatment of HIV infection; however, if patients with HIV infection are treated with Hydroxyurea, and in particular, in combination with didanosine and/or stavudine, close monitoring for signs and symptoms of pancreatitis is recommended. Permanently discontinue therapy with Hydroxyurea in patients who develop signs and symptoms of pancreatitis.


Hepatotoxicity and hepatic failure resulting in death have been reported during postmarketing surveillance in patients with HIV infection treated with Hydroxyurea and other antiretroviral drugs. Fatal hepatic events were reported most often in patients treated with the combination of Hydroxyurea, didanosine, and stavudine. Avoid this combination.

Peripheral Neuropathy

Peripheral neuropathy, which was severe in some cases, has been reported in patients with HIV infection receiving Hydroxyurea in combination with antiretroviral drugs, including didanosine, with or without stavudine.

Test Interference

Interference with Uric Acid, Urea, or Lactic Acid Assays

Studies have shown that there is an analytical interference of Hydroxyurea with the enzymes (urease, uricase, and lactate dehydrogenase) used in the determination of urea, uric acid, and lactic acid, rendering falsely elevated results of these in patients treated with Hydroxyurea.



Teratogenic Effects

Pregnancy Category D

Risk Summary

Hydroxyurea can cause fetal harm when administered to a pregnant woman. There are no adequate and well-controlled studies in pregnant women. If this drug is used during pregnancy or if the patient becomes pregnant while taking this drug, the patient should be apprised of the potential harm to the fetus. Women of childbearing potential should be advised to avoid becoming pregnant.

Drugs which affect DNA synthesis, such as Hydroxyurea, may be potential mutagenic agents.

The physician should carefully consider this possibility before administering this drug to male or female patients who may contemplate conception [see Warnings and Precautions (5.3)].

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 maximum recommended human daily dose on a mg/m2 basis) in rats and at 30 mg/kg/day (about 0.3 times the maximum recommended 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 maximum recommended human daily dose on a mg/m2 basis) to rats caused growth retardation and impaired learning ability.

Nursing Mothers

Hydroxyurea is excreted in human milk. Because of the potential for serious adverse reactions with Hydroxyurea, discontinue nursing during treatment with Hydroxyurea.

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 (2.3)].

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 Hydroxyurea is to be administered to these patients [see Dosage and Administration (2.3) and Clinical Pharmacology (12.3)].

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.


Acute mucocutaneous toxicity has been reported in patients receiving Hydroxyurea at dosages several times the therapeutic dose. Soreness, violet erythema, edema on palms and soles followed by scaling of hands and feet, severe generalized hyperpigmentation of the skin, and stomatitis have also been observed.

Hydroxyurea Description

Hydroxyurea Capsules USP are an antineoplastic agent available for oral use as capsules providing 500 mg Hydroxyurea, USP. Inactive ingredients: anhydrous citric acid, benzyl alcohol, black iron oxide, butylparaben, carboxymethylcellulose sodium, D & C red no. 28, D & C yellow no. 10 aluminum lake, dibasic sodium phosphate, edetate calcium disodium, FD & C blue no. 1, FD & C blue no. 1 aluminum lake, FD & C blue no. 2 aluminum lake, FD & C red no. 40, FD & C red no. 40 aluminum lake, gelatin, lactose monohydrate, magnesium stearate, methylparaben, pharmaceutical glaze, propylparaben, propylene glycol, red iron oxide, sodium lauryl sulfate, sodium propionate, and titanium dioxide.

Hydroxyurea is an essentially tasteless, white crystalline powder. Its structural formula is:

CH4N2O2 M.W. 76.05

CH4N2O2 M.W. 76.05

Hydroxyurea - Clinical Pharmacology

Mechanism of Action

The precise mechanism by which Hydroxyurea produces its antineoplastic effects cannot, at present, be described. However, the reports of various studies in tissue culture in rats and humans lend support to the hypothesis that Hydroxyurea causes an immediate inhibition of DNA synthesis by acting as a ribonucleotide reductase inhibitor, without interfering with the synthesis of ribonucleic acid or of protein. This hypothesis explains why, under certain conditions, Hydroxyurea may induce teratogenic effects.

Three mechanisms of action have been postulated for the increased effectiveness of concomitant use of Hydroxyurea therapy with irradiation on squamous cell (epidermoid) carcinomas of the head and neck. In vitro studies utilizing Chinese hamster cells suggest that Hydroxyurea (1) is lethal to normally radioresistant S-stage cells, and (2) holds other cells of the cell cycle in the G1 or pre-DNA synthesis stage where they are most susceptible to the effects of irradiation. The third mechanism of action has been theorized on the basis of in vitro studies of HeLa cells. It appears that Hydroxyurea, by inhibition of DNA synthesis, hinders the normal repair process of cells damaged but not killed by irradiation, thereby decreasing their survival rate; RNA and protein syntheses have shown no alteration.



Following oral administration of Hydroxyurea, Hydroxyurea reaches peak plasma concentrations in 1 to 4 hours. Mean peak plasma concentrations and AUCs increase more than proportionally with increase of dose.

There are no data on the effect of food on the absorption of Hydroxyurea.


Hydroxyurea distributes throughout the body with a volume of distribution approximating total body water.

Hydroxyurea concentrates in leukocytes and erythrocytes.


Up to 60% of an oral dose undergoes conversion through saturable hepatic metabolism and a minor pathway of degradation by urease found in intestinal bacteria.


In patients with sickle cell anemia, the mean cumulative urinary recovery of Hydroxyurea was about 40% of the administered dose.

Specific Populations

Renal Impairment

The effect of renal impairment on the pharmacokinetics of Hydroxyurea was assessed in adult patients with sickle cell disease and renal impairment. Patients with normal renal function (creatinine clearance [CrCl] >80 mL/min), mild (CrCl 50 to 80 mL/min), moderate (CrCl = 30 to <50 mL/min), or severe (<30 mL/min) renal impairment received a single oral dose of 15 mg/kg Hydroxyurea. Patients with ESRD received two doses of 15 mg/kg separated by 7 days; the first was given following a 4-hour hemodialysis session, the second prior to hemodialysis. The exposure to Hydroxyurea (mean AUC) in patients with CrCl <60 mL/min and those with ESRD was 64% higher than in patients with normal renal function (CrCl >60 mL/min). Reduce the dose of Hydroxyurea when it is administered to patients with creatinine clearance of <60 mL/min or with ESRD following hemodialysis[see Dosage and Administration (2.3) and Use in Specific Populations (8.6)].

Nonclinical Toxicology

Carcinogenesis, Mutagenesis, Impairment of Fertility

See Warnings and Precautions (5.2) for carcinogenesis and mutagenesis information.

Conventional long-term studies to evaluate the carcinogenic potential of Hydroxyurea have not been performed. However, intraperitoneal administration of 125 to 250 mg/kg Hydroxyurea (about 0.6 to1.2 times the maximum recommended 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.

Impairment of Fertility: Hydroxyurea administered to male rats at 60 mg/kg/day (about 0.3 times the maximum recommended human daily dose on a mg/m2 basis) produced testicular atrophy, decreased spermatogenesis, and significantly reduced their ability to impregnate females.



How Supplied/Storage and Handling

How Supplied

Hydroxyurea Capsules USP 500 mg are available as a two-piece hard gelatin capsule with purple opaque cap and pink opaque body filled with white powder, imprinted in black ink barr 882 and packaged in bottles of 100 capsules (NDC 0555-0882-02).


Store at 20º to 25ºC (68º to 77ºF) [See USP Controlled Room Temperature].

Dispense in a tight, light-resistant container as defined in the USP, with a child-resistant closure (as required).




Handling and Disposal

Hydroxyurea Capsules USP are a cytotoxic drug. Follow applicable special handling and disposal procedures [see References (15)].

To decrease the risk of contact, advise caregivers to wear disposable gloves when handling Hydroxyurea Capsules USP or bottles containing Hydroxyurea Capsules USP. Wash hands with soap and water before and after contact with the bottle or capsules when handling Hydroxyurea Capsules USP. Do not open Hydroxyurea Capsules USP. Avoid exposure to crushed or opened capsules. If contact with crushed or opened capsules occurs on the skin, wash affected area immediately and thoroughly with soap and water. If contact with crushed or opened capsules occurs on the eye(s), the affected area should be flushed thoroughly with water or isotonic eyewash designated for that purpose for at least 15 minutes. If the powder from the capsule is spilled, immediately wipe it up with a damp disposable towel and discard in a closed container, such as a plastic bag; as should the empty capsules. The spill areas should then be cleaned three times using a detergent solution followed by clean water. Keep the medication away from children and pets. Contact your doctor for instructions on how to dispose of outdated capsules.

Patient Counseling Information

There is a risk of myelosuppression. Monitoring blood counts weekly throughout the duration of therapy should be emphasized to patients taking Hydroxyurea [see Warnings and Precautions (5.1)]. Advise patients to report signs and symptoms of infection or bleeding immediately.
Advise patients that there is a risk of cutaneous vasculitic toxicities and secondary malignancies including leukemia and skin cancers [see Warnings and Precautions (5.2, 5.4)].
Advise females of reproductive potential of the potential risk to a fetus and to inform their healthcare provider of a known or suspected pregnancy. Advise females and males of reproductive potential to use contraception during and after treatment with Hydroxyurea [see Warnings and Precautions (5.3) and Use in Specific Populations (8.1)].
Advise females to discontinue breastfeeding during treatment with Hydroxyurea [see Use in Specific Populations (8.3)].
Patients with HIV infection should contact their physician for signs and symptoms of pancreatitis, hepatic events, and peripheral neuropathy [see Warnings and Precautions (5.5)].
Postirradiation erythema can occur in patients who have received previous irradiation therapy [see Warnings and Precautions (5.6)].


North Wales, PA 19454

Rev. B 7/2015

Package/Label Display Panel

Hydroxyurea Capsules USP 500 mg 100s Label Text

NDC 0555-0882-02

Capsules USP
500 mg

Caution: Cytotoxic, Special
Handling Procedures

Rx only



Hydroxyurea capsule
Product Information
Product Type HUMAN PRESCRIPTION DRUG LABEL Item Code (Source) NDC:0555-0882
Route of Administration ORAL DEA Schedule     
Active Ingredient/Active Moiety
Ingredient Name Basis of Strength Strength
Hydroxyurea (Hydroxyurea) Hydroxyurea 500 mg
Inactive Ingredients
Ingredient Name Strength
D&C RED NO. 28  
FD&C RED NO. 40  
Product Characteristics
Color PURPLE, PINK Score no score
Shape CAPSULE Size 22mm
Flavor Imprint Code barr;882
# Item Code Package Description
1 NDC:0555-0882-02 100 CAPSULE in 1 BOTTLE
Marketing Information
Marketing Category Application Number or Monograph Citation Marketing Start Date Marketing End Date
ANDA ANDA075143 10/19/1998
Labeler - Barr Laboratories Inc. (802716563)
Revised: 08/2015
Barr Laboratories Inc.