Dosage Forms
Excipient information presented when available (limited, particularly for generics); consult specific product labeling. [DSC] = Discontinued product
Solution, Intravenous, as chloride [preservative free]:
Metastron: 1 mCi/mL (4 mL [DSC]) [pyrogen free]
Pharmacology
Mechanism of Action
Strontium-89 selectively localizes in metastatic bone lesions emitting beta radiation to reduce pain.
Pharmacokinetics/Pharmacodynamics
Distribution
Selectively localizes in bone mineral (preferentially to metastatic bone lesions)
Excretion
In patients with bone metastases: Urine (67%); feces (33%)
Onset of Action
Pain relief: 7 to 20 days
Use: Labeled Indications
Skeletal metastases (bone pain): Relief of bone pain in patients with skeletal metastases.
Limitation of use: Confirm the presence of bone metastases prior to therapy.
Contraindications
There are no contraindications listed in the manufacturer’s labeling.
Dosage and Administration
Dosing: Adult
Skeletal metastases (bone pain): IV: 148 megabecquerel (MBq; 4 millicurie [mCi]) or 1.5 to 2.2 MBq (40 to 60 microCi)/kg; repeat doses should be based on individual response, symptoms, and blood counts and are generally not recommended at intervals <90 days. Measure dose by a suitable radioactivity calibration system immediately prior to administration.
Dosing: Geriatric
Refer to adult dosing.
Administration
IV: Administer intravenously slowly over 1 to 2 minutes. Radiopharmaceutical; use appropriate precautions for handling and disposal.
Storage
Store vial (and contents) at 15°C to 25°C (59°F to 77°F); store in transportation shield container.
Drug Interactions
There are no known significant interactions.
Adverse Reactions
Frequency not defined.
Cardiovascular: Flushing (after rapid injection)
Hematologic & oncologic: Leukopenia, thrombocytopenia (nadir: 12 to 16 weeks; recovery: 6 months)
Neuromuscular & skeletal: Ostealgia (transient increase; duration: 36 to 72 hours)
<1%, postmarketing, and/or case reports: Chills, fever, hot flash, septicemia
Warnings/Precautions
Concerns related to adverse effects:
- Bone marrow suppression: Bone marrow toxicity (thrombocytopenia and leukopenia) is likely to occur. Use is not recommended in patients with seriously compromised bone marrow function from prior therapies or from disease infiltration (unless potential benefit outweighs risks). Monitor CBC at least every other week. The platelet nadir typically occurs between 12 and 16 weeks following administration; platelets and WBC recovery occur slowly, generally reaching baseline levels 6 months after treatment in the absence of other therapy interventions or disease progression. Use with caution in patients with platelets <60,000/mm3 or WBCs <2,400/mm3. Carefully evaluate bone marrow status and toxicity of initial dose if considering repeat administration.
- Bone pain: A small number of patients have experienced a transient increase in bone pain at 36 to 72 hours after administration; this is generally mild and self-limiting.
- Flushing: A flushing sensation has been reported following rapid (<30 seconds) injection.
Disease-related concerns:
- Incontinence: Incontinent patients may require urinary catheterization (to minimize radioactive contamination of clothing, bedding, and/or environment).
- Renal impairment: Primarily eliminated renally; possible risk versus benefit should be evaluated in patients with renal impairment.
Special handling:
- Radiopharmaceutical: Use appropriate precautions for handling, disposal, and minimizing exposure to patients and healthcare personnel. Use only under supervision of individuals with experience/training in the handling of radioactive materials approved by the applicable regulatory authority. Patients should take the following precautions to minimize exposure (Silberstein 2003): Avoid soiling underclothing or areas around toilet bowls for 2 weeks after injection. Wash any underclothing separately if significantly stained with urine. Where a normal toilet is available, sit to urinate in preference to a urinal. Flush toilet twice after use. Wash hands thoroughly after urination.
Other warnings/precautions:
- Appropriate use: Strontium-89 is not indicated for use in patients with cancer not involving bone. Due to delayed onset of pain relief (7 to 20 days following administration), also not indicated for use in patients with a short life expectancy.
Monitoring Parameters
CBC with differential (at least every other week)
Pregnancy
Pregnancy Risk Factor
D
Pregnancy Considerations
May cause fetal harm if administered during pregnancy. Women of childbearing potential should avoid becoming pregnant.
Patient Education
- Discuss specific use of drug and side effects with patient as it relates to treatment. (HCAHPS: During this hospital stay, were you given any medicine that you had not taken before? Before giving you any new medicine, how often did hospital staff tell you what the medicine was for? How often did hospital staff describe possible side effects in a way you could understand?)
- Patient may experience flushing or bone pain. Have patient report immediately to prescriber signs of infection, signs of bleeding (vomiting blood or vomit that looks like coffee grounds, coughing up blood, blood in the urine, black, red, or tarry stools, bleeding from the gums, abnormal vaginal bleeding, bruises without a reason or that get bigger, or any bleeding that is very bad or that will not stop), or severe loss of strength and energy (HCAHPS).
- Educate patient about signs of a significant reaction (eg, wheezing; chest tightness; fever; itching; bad cough; blue skin color; seizures; or swelling of face, lips, tongue, or throat). Note: This is not a comprehensive list of all side effects. Patient should consult prescriber for additional questions.
Intended Use and Disclaimer: Should not be printed and given to patients. This information is intended to serve as a concise initial reference for health care professionals to use when discussing medications with a patient. You must ultimately rely on your own discretion, experience, and judgment in diagnosing, treating, and advising patients.
