Doxorubicin Hydrochloride (Page 4 of 7)

8.3 Nursing Mothers

Doxorubicin has been detected in the milk of at least one lactating patient [see Clinical Pharmacology (12.3)]. Because of the potential for serious adverse reactions in nursing infants from doxorubicin, a decision should be made whether to discontinue nursing or discontinue the drug, taking into account the importance of the drug to the mother.

8.4 Pediatric Use

Based on postmarketing reports, pediatric patients treated with doxorubicin are at risk for developing late cardiovascular dysfunction. Risk factors include young age at treatment (especially < 5 years), high cumulative doses and receipt of combined modality therapy. Long-term periodic cardiovascular monitoring is recommended for all pediatric patients who have received doxorubicin. Doxorubicin, as a component of intensive chemotherapy regimens administered to pediatric patients, may contribute to prepubertal growth failure and may also contribute to gonadal impairment, which is usually temporary.

There are no recommended dose adjustments based on age. Doxorubicin clearance was increased in patients aged 2 years to 20 years as compared to adults, while doxorubicin clearance was similar in children less than 2 years as compared to adults [see Clinical Pharmacology (12.3)].

8.5 Geriatric Use

Clinical experience in patients who were 65 years of age and older who received doxorubicin based chemotherapy regimens for metastatic breast cancer showed no overall differences in safety and effectiveness compared with younger patients.

8.6 Females and Males of Reproductive Potential

Contraception

Females

Doxorubicin can cause fetal harm when administered during pregnancy. Advise female patients of reproductive potential to use highly effective contraception during treatment with doxorubicin and for 6 months after treatment. Advise patients to contact their healthcare provider if they become pregnant, or if pregnancy is suspected, while taking doxorubicin [see Use in Specific Populations (8.1)].

Males

Doxorubicin may damage spermatozoa and testicular tissue, resulting in possible genetic fetal abnormalities. Males with female sexual partners of reproductive potential should use effective contraception during and for 6 months after treatment [see Nonclinical Toxicology (13.1)].

Infertility

Females

In females of reproductive potential, doxorubicin may cause infertility and result in amenorrhea. Premature menopause can occur. Recovery of menses and ovulation is related to age at treatment [see Nonclinical Toxicology (13.1)].

Males

Doxorubicin may result in oligospermia, azoospermia, and permanent loss of fertility. Sperm counts have been reported to return to normal levels in some men. This may occur several years after the end of therapy.

8.7 Hepatic Impairment

The clearance of doxorubicin was reduced in patients with elevated serum bilirubin levels. Reduce the dose of doxorubicin in patients with serum bilirubin levels greater than 1.2 mg/dL [see Dosage and Administration (2.2) and Warnings and Precautions (5.5)].

Doxorubicin is contraindicated in patients with severe hepatic impairment (defined as Child Pugh Class C or serum bilirubin levels greater than 5 mg/dL) [see Contraindications (4)].

10 OVERDOSAGE

Few cases of overdose have been described. A 58-year-old man with acute lymphoblastic leukemia received 10-fold overdose of doxorubicin (300 mg/m2) in one day. He was treated with charcoal filtration, hemopoietic growth factor (G-CSF), proton pump inhibitor and antimicrobial prophylaxis. The patient suffered sinus tachycardia, grade 4 neutropenia and thrombocytopenia for 11 days, severe mucositis and sepsis. The patient recovered completely 26 days after the overdose. A 17-year-old girl with osteogenic sarcoma received 150 mg of doxorubicin daily for 2 days (intended dose was 50 mg per day for 3 days). The patient developed severe mucositis on days 4 to 7 after the overdose and chills and pyrexia on day 7. The patient was treated with antibiotics and platelets and recovered 18 days after overdose.

11 DESCRIPTION

Doxorubicin is a cytotoxic anthracycline antibiotic isolated from cultures of Streptomyces peucetius var.caesius. Doxorubicin consists of a naphthacenequinone nucleus linked through a glycosidic bond at ring atom 7 to an amino sugar, daunosamine. Chemically, doxorubicin hydrochloride is (8S,10S)-10-[(3-Amino-2,3,6-trideoxy-a-L-lyxo-hexopyranosyl)-oxy]-8-glycoloyl-7,8,9,10-tetrahydro-6,8,11-trihydroxy-1-methoxy-5,12-naphthacenedione hydrochloride. The structural formula is as follows:

structure
(click image for full-size original)

Doxorubicin binds to nucleic acids, presumably by specific intercalation of the planar anthracycline nucleus with the DNA double helix. The anthracycline ring is lipophilic, but the saturated end of the ring system contains abundant hydroxyl groups adjacent to the amino sugar, producing a hydrophilic center. The molecule is amphoteric, containing acidic functions in the ring phenolic groups and a basic function in the sugar amino group. It binds to cell membranes as well as plasma proteins.

It is supplied in the hydrochloride form as a sterile parenteral, isotonic solution with sodium chloride for intravenous use only.

DOXOrubicin HCI Injection, USP:

Each 2 mg/mL, 5 mL (10 mg) vial contains 10 mg Doxorubicin Hydrochloride, USP; Sodium Chloride 0.9% (to adjust tonicity) and Water for Injection q.s.; pH adjusted to 3 using Hydrochloric Acid.

Each 2 mg/mL, 10 mL (20 mg) vial contains 20 mg Doxorubicin Hydrochloride, USP; Sodium Chloride 0.9% (to adjust tonicity) and Water for Injection q.s.; pH adjusted to 3 using Hydrochloric Acid.

Each 2 mg/mL, 25 mL (50 mg) vial contains 50 mg Doxorubicin Hydrochloride, USP; Sodium Chloride 0.9% (to adjust tonicity) and Water for Injection q.s.; pH adjusted to 3 using Hydrochloric Acid.

Each 2 mg/mL, 100 mL (200 mg) multiple dose vial contains 200 mg Doxorubicin Hydrochloride, USP; Sodium Chloride 0.9% (to adjust tonicity) and Water for Injection q.s.; pH adjusted to 3 using Hydrochloric Acid.

12 CLINICAL PHARMACOLOGY

12.1 Mechanism of Action

The cytotoxic effect of doxorubicin on malignant cells and its toxic effects on various organs are thought to be related to nucleotide base intercalation and cell membrane lipid binding activities of doxorubicin. Intercalation inhibits nucleotide replication and action of DNA and RNA polymerases. The interaction of doxorubicin with topoisomerase II to form DNA-cleavable complexes appears to be an important mechanism of doxorubicin cytocidal activity.

12.3 Pharmacokinetics

Pharmacokinetic studies conducted in patients with various types of tumors have shown that doxorubicin follows multiphasic disposition after intravenous injection. The distribution half-life is approximately 5 minutes, while the terminal half-life is 20 to 48 hours. In four patients, doxorubicin demonstrated dose-independent pharmacokinetics across a dose range of 30 to 70 mg/m2 .

Distribution

Steady-state distribution volume ranges from 809 to 1214 L/m2. Binding of doxorubicin and its major metabolite, doxorubicinol, to plasma proteins is about 75% and is independent of plasma concentration of doxorubicin up to 1.1 mcg/mL.

Doxorubicin was measured in the milk of one lactating patient after therapy with 70 mg/m2 of doxorubicin given as a 15-minute intravenous infusion. The peak milk concentration at 24 hours after treatment was 4.4-fold greater than the corresponding plasma concentration. Doxorubicin was detectable in the milk up to 72 hours.

Doxorubicin does not cross the blood brain barrier.

Metabolism

Enzymatic reduction at the 7 position and cleavage of the daunosamine sugar yields aglycones which are accompanied by free radical formation, the local production of which may contribute to the cardiotoxic activity of doxorubicin. Disposition of doxorubicinol in patients is formation rate limited, with the terminal half-life of doxorubicinol being similar to doxorubicin. The relative exposure of doxorubicinol, i.e., the ratio between the AUC of doxorubicinol and the AUC of doxorubicin is approximately 0.5.

Excretion

Plasma clearance is in the range 324 to 809 mL/min/m2 and is predominately by metabolism and biliary excretion. Approximately 40% of the dose appears in the bile in 5 days, while only 5 to 12% of the drug and its metabolites appear in the urine during the same time period. In urine, <3% of the dose was recovered as doxorubicinol over 7 days.

Systemic clearance of doxorubicin is significantly reduced in obese women with ideal body weight greater than 130%. There was a significant reduction in clearance without any change in volume of distribution in obese patients when compared with normal patients with less than 115% ideal body weight.

Pediatric patients

Following administration of doses ranging from 10 to 75 mg/m2 of doxorubicin to 60 children and adolescents ranging from 2 months to 20 years of age, doxorubicin clearance averaged 1443 ± 114 mL/min/m2. Further analysis demonstrated that clearance in 52 children greater than 2 years of age (1540 mL/min/m2) was increased compared with adults. However, clearance in infants younger than 2 years of age (813 mL/min/m2) was decreased compared with older children and approached the range of clearance values determined in adults [see Use in Specific Populations (8.4 )].

Patient Gender

There is no recommended dose adjustment based on gender. A published clinical study involving 6 men and 21 women with no prior anthracycline therapy reported a significantly higher median doxorubicin clearance in men compared to women (1088 mL/min/m2 versus 433 mL/min/m2). However, the terminal half-life of doxorubicin was longer in men compared to women (54 versus 35 hours).

Patients with hepatic impairment

The clearance of doxorubicin and doxorubicinol was reduced in patients with elevation in serum bilirubin [see Dosage and Administration (2.2 ) and Warnings and Precautions (5.5 )].

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