PHYSICAL CHARACTERISTICS
Strontium-89 decays by beta emission with a physical half-life of 50.5 days. The maximum beta energy is 1.463 MeV (100%). The maximum range of β- from Strontium-89 in tissue is approximately 8 mm.
Radioactive decay factors to be applied to the stated value for radioactive concentration at calibration, when calculating injection volumes at the time of administration, are given in Table 1.
Table 1: Decay of Strontium-89 DayDays before (-) or after (+) the calibration date stated on the vial. Factor Day Factor
-24 1.39 +6 0.92
-22 1.35 +8 0.90
-20 1.32 +10 0.87
-18 1.28 +12 0.85
-16 1.25 +14 0.83
-14 1.21 +16 0.80
-12 1.18 +18 0.78
-10 1.15 +20 0.76
-8 1.12 +22 0.74
-6 1.09 +24 0.72
-4 1.06 +26 0.70
-2 1.03 +28 0.68
0=calibration 1.00
CLINICAL PHARMACOLOGY
Following intravenous injection, soluble strontium compounds behave like their calcium analogs, clearing rapidly from the blood and selectively localizing in bone mineral. Uptake of strontium by bone occurs preferentially in sites of active osteogenesis; thus primary bone tumors and areas of metastatic involvement (blastic lesions) can accumulate significantly greater concentrations of strontium than surrounding normal bone.
Strontium-89 Chloride is retained in metastatic bone lesions much longer than in normal bone, where turnover is about 14 days. In patients with extensive skeletal metastases, well over half of the injected dose is retained in the bones.
Excretion pathways are two-thirds urinary and one-third fecal in patients with bone metastases. Urinary excretion is higher in people without bone lesions. Urinary excretion is greatest in the first two days following injection.
Strontium-89 is a pure beta emitter and Strontium-89 Chloride selectively irradiates sites of primary and metastatic bone involvement with minimal irradiation of soft tissues distant from the bone lesions. (The maximum range in tissue is 8 mm; maximum energy is 1.463 MeV.) Mean absorbed radiation doses are uled under the Radiation Dosimetry section.
Clinical trials have examined relief of pain in cancer patients who have received therapy for bone metastases (external radiation to indexed sites) but in whom persistent pain recurred. In a multi-center Canadian placebo-controlled trial of 126 patients, pain relief occurred in more patients treated with a single injection of Metastron than in patients treated with an injection of placebo. Results are given in the following tables.
Table 2 compares the percentage and number of patients treated with Metastron or placebo who had reduced pain and no increase in analgesic or radiotherapy re-treatment.
Table 2: Comparison of the effects of Strontium-89 and placebo, as adjunct to radiotherapy, on treatment outcome over time. Months Post-Treatment
1 2 3 4 5 6
Metastron 71.4% 78.9% 60.6% 59.3% 36.4% 63.6%
(n=42) (n=38) (n=33) (n=27) (n=22) (n=22)
Placebo 61.4% 57.1% 55.9% 25.0% 31.8% 35.0%
(n=44) (n=35) (n=34) (n=24) (n=22) (n=20)
At each visit, treatment success, defined as a reduction in a patient's pain score without any increase in analgesic intake and without any supplementary radiotherapy at the index site, was more frequent among patients assigned to Metastron than to placebo.
Table 3 compares the number and percentage of patients treated with Metastron or placebo as an adjunct to radiotherapy who were pain free without analgesic at the intervals shown.
Table 3: Comparison of the effects of Strontium-89 and placebo, as adjunct to radiotherapy, on reduction of pain score and analgesic score to zero. Months Post-Treatment
1 2 3 4 5 6 9
Metastron 6 5 5 3 4 4 2
14.3% 13.2% 15.2% 11.1% 18.2% 18.2% 18.2%
(n=42) (n=38) (n=33) (n=27) (n=22) (n=22) (n=11)
Placebo 3 3 2 0 1 1 0
6.8% 8.6% 5.9% 4.5% 5%
(n=44) (n=35) (n=34) (n=24) (n=22) (n=20) (n=17)
The number of patients classified at each visit as treatment successes who were pain free at the index site and required no analgesics was consistently higher in the Metastron group.
New pain sites were less frequent in patients treated with Metastron.
In another clinical trial, pain relief was greater in a group of patients treated with Metastron compared with a group treated with non-radioactive strontium-88.
(from the Metastron Drug Information)
Here is a very useful document describing all the issues with strontium-89.
[credit to the Victorian Department of Human Services, Radiation Safety Program]
A patient fact sheet from here
| Strontium-89 Chloride |
About your treatment
Your doctor has ordered the drug strontium-89 chloride to help treat your illness. The drug is given by injection into a vein or a catheter that has been placed in a vein.
This medication is used to:
- relieve bone pain
This medication is sometimes prescribed for other uses; ask your doctor or pharmacist for more information.
Strontium-89 chloride is in a class of drugs known as radioisotopes. It delivers radiation to cancer sites and ultimately decreases bone pain. The length of treatment depends on the types of drugs you are taking, how well your body responds to them, and the type of cancer you have.
Precautions
Before taking strontium-89 chloride,
- tell your doctor and pharmacist if you are allergic to strontium-89 chloride or any other drugs.
- tell your doctor and pharmacist what prescription and nonprescription medications you are taking, especially aspirin and vitamins.
- tell your doctor if you have or have ever had bone marrow disease, blood disorders, or kidney disease.
- you should know that strontium-89 chloride may interfere with the normal menstrual cycle (period) in women and may stop sperm production in men. However, you should not assume that you cannot get pregnant or that you cannot get someone else pregnant. Women who are pregnant or breast-feeding should tell their doctors before they begin taking this drug. You should not plan to have children while receiving chemotherapy or for a while after treatments. (Talk to your doctor for further details.) Use a reliable method of birth control to prevent pregnancy. Strontium-89 chloride may harm the fetus.
- notify any health care professional (especially other doctors) giving you treatment that you will be taking strontium-89 chloride.
- do not have any vaccinations (e.g., measles or flu shots) without talking to your doctor.
Side effects
Side effects from strontium-89 chloride are common and include:
- increased pain starting 2-3 days after treatment and lasting 2-3 days
- flushing
- diarrhea
Tell your doctor if the following symptom is severe or lasts for several hours:
- fatigue
If you experience any of the following symptoms, call your doctor immediately:
- unusual bruising or bleeding
- no decrease in pain 7 days after treatment
- fever
- chills
Special instructions
- Because this medication may be present in your blood and urine for about 1 week after an injection, you should follow certain precautions during this time. Use a normal toilet instead of a urinal, if possible, and flush the toilet twice after each use. Also wash your hands with soap and water after using the toilet. Wipe any spilled urine or blood with a tissue and flush the tissue away. Immediately wash any stained clothes or bed linens separately from other laundry.
- The most common side effect of strontium-89 chloride is a decrease of blood cells. Your doctor may order tests before, during, and after your treatment to see if your blood cells are affected by the drug.
Brand names
- Metastron®