Rubex

Action

Unclear. Thought to inhibit DNA and RNA synthesis by forming complex with DNA. Also exerts immunosuppressive activity. Cell-cycle-S-phase specific.

Availability

Injection (preservative-free): 2 mg/ml

Powder for injection: 10 mg, 20 mg, 50 mg

Indications and dosages

➣ Solid tumors, including bladder, breast, lung, stomach, and thyroid cancers; malignant lymphomas, including Hodgkin's disease; acute leukemia; chronic lymphocytic leukemia; multiple myeloma; Wilms' tumor; neuroblastoma

Adults: 60 to 75 mg/m² I.V. as a single dose at 21-day cycles, or 30 mg/m² I.V. as a single daily dose on first to third days of 4-week cycle, or 20 mg/m² I.V. once weekly. Maximum cumulative dosage is 550 mg/m².

Dosage adjustment

• Bone marrow depression

• Impaired cardiac or hepatic function

Off-label uses

• Endometrial carcinoma, islet cell carcinoma

Contraindications

• Hypersensitivity to drug

• Severe bone marrow depression

• Previous treatment with maximum cumulative doses of doxorubicin, other anthracyclines, or anthracenes

Precautions

Use cautiously in:

• cardiac disease, hepatic impairment, depressed bone marrow reserve, CNS metastases, brain tumor, malignant melanoma, renal carcinoma

• elderly patients

• females of childbearing age

• pregnant or breastfeeding patients

• children.

Administration

• Follow facility policy for handling and preparing antineoplastics.

☞ Don't dilute solution with bacteriostatic diluent. Don't mix with other drugs.

• Dilute as directed with normal saline solution to a final concentration of 2 mg/ml.

• Administer slowly over 3 to 5 minutes into tubing of free-flowing I.V. infusion of normal saline solution or dextrose 5% in water.

• Deliver into large vein using butterfly needle. Avoid veins over joints or extremities with compromised venous or lymphatic drainage.

☞ Avoid rapid infusion, because this may increase risk of acute infusion-related reactions (back pain, chest tightness, flushing).

☞ If extravasation occurs, stop infusion immediately, apply ice, and notify prescriber.

Adverse reactions

CNS: drowsiness, dizziness, asthenia, fatigue, malaise, paresthesia, headache, depression, insomnia, anxiety, emotional lability

CV: chest pain, hypotension, tachycardia, peripheral edema, cardiomyopathy, heart failure, arrhythmias, pericardial effusion

GI: nausea, vomiting, diarrhea, constipation, enlarged abdomen, abdominal pain, dyspepsia, oral candidiasis, moniliasis, stomatitis, glossitis, esophagitis, dysphagia

GU: albuminuria, hyperuricosuria, red urine

Hematologic: anemia, leukopenia, thrombocytopenia, neutropenia, bone marrow depression

Metabolic: hyperglycemia, hypocalcemia

Musculoskeletal: myalgia, back pain

Respiratory: dyspnea, increased cough, pneumonia

Skin: rash, dry skin, pruritus, skin discoloration, alopecia, diaphoresis, exfoliative dermatitis, palmar-plantar erythrodysesthesia

Other: abnormal taste, infection, chills, fever, herpes zoster, injection site reactions, allergic reactions including anaphylaxis, acute infusion-associated reactions

Interactions

Drug-drug. Antineoplastics: additive bone marrow depression

Cyclophosphamide: increased risk of hemorrhagic cystitis, increased cardiotoxicity

Cyclosporine: profound and prolonged hematologic toxicity, increased risk of coma and seizures

Dactinomycin (in children): increased risk of pneumonitis

Live-virus vaccines: decreased antibody response to vaccine, increased risk of adverse reactions

Mercaptopurine: hepatitis

Paclitaxel (if given first): reduced doxorubicin clearance, increased incidence and severity of neutropenia and stomatitis

Phenobarbital: increased clearance and decreased effects of doxorubicin

Phenytoin: decreased phenytoin blood level

Progesterone: increased incidence and severity of neutropenia and thrombocytopenia

Streptozocin: increased doxorubicin half-life

Verapamil: increased doxorubicin blood level

Drug-diagnostic tests. Alkaline phosphatase, bilirubin, glucose, prothrombin time, serum and urine uric acid: increased levels

Calcium, hemoglobin, neutrophils, platelets, white blood cells (WBCs): decreased levels

Patient monitoring

☞ Watch for acute life-threatening arrhythmias, which may occur during or within a few hours after administration.

☞ Monitor for cardiomyopathy and subsequent heart failure with chronic overdose (more common in children).

• Stay alert for erythematous streaking along vein next to injection site, which may indicate too-rapid infusion.

• Watch for nausea and vomiting. Administer antiemetics as needed.

☞ Check for superinfection or hemorrhage caused by persistent bone marrow depression (but expect WBC counts as low as 1,000/mm³ during therapy).

☞ Watch closely for infusion-related reactions and anaphylaxis.

• Monitor CBC, hepatic profile, coagulation tests, ejection fraction, and glucose, uric acid, bilirubin, and calcium blood levels.

Patient teaching

☞ Advise patient to promptly report irregular heartbeats, easy bruising or bleeding, or signs of hypersensitivity reaction, such as a rash.

• Caution patient to avoid people with colds, flu, or other contagious illnesses.

• Explain that drug may cause complete but reversible hair loss.

• Inform patient that drug may turn urine red for 1 or 2 days.

• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs and tests mentioned above.