Quadramet

Drug Description
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QUADRAMET®
(samarium SM 153 lexidronam) Injection

Therapeutic – For Intravenous Administration

DRUG DESCRIPTION

QUADRAMET® is a therapeutic agent consisting of radioactive samarium and a tetraphosphonate chelator, ethylenediaminetetramethylenephosphonic acid (EDTMP). QUADRAMET® is formulated as a sterile, non-pyrogenic, clear, colorless to light amber isotonic solution of samarium-153 lexidronam for intravenous administration.

QUADRAMET® does not contain a preservative.

Each milliliter contains 35 mg EDTMP•H2O, 5.3 mg Ca [as Ca(OH)2], 14.1 mg Na [as NaOH], equivalent to 44 mg Ca/Na EDTMP (anhydrous calc.), 5-46 µg samarium (specific activity of approximately 1.0-11.0 mCi/µg Sm), and 1850 ± 185 MBq (50 ± 5 mCi) of samarium-153 at calibration.

The structural formula of samarium lexidronam pentasodium is:

QUADRAMET® (samarium lexidronam pentasodium) Structural Formula Illustration

The ionic formula is 153Sm+3 [CH2N(CH2PO3-2)2]2 and the ionic formula weight is 581.1 daltons (pentasodium form, 696).

The pH of the solution is 7.0 to 8.5.

QUADRAMET® is supplied frozen in single-dose glass vials containing 3 mL with 5550 MBq (150 mCi) of samarium-153 at calibration.

Physical Characteristics: Samarium-153 is produced in high yield and purity by neutron irradiation of isotopically enriched samarium Sm 152 oxide (152 Sm2O3). It emits both medium-energy beta particles and a gamma photon, and has a physical half-life of 46.3 hours (1.93 days). Samarium-153 has average and maximum beta particle ranges in water of 0.5 mm and 3.0 mm, respectively. The primary radiation emissions of samarium-153 are shown in Table 1.

TABLE 1 - SAMARIUM-153 PRINCIPAL RADIATION EMISSION DATA

  Radiation Energy (keV)* Abundance
Beta 640 30%
Beta 710 50%
Beta 810 20%
Gamma 103 29%
* Maximum energies are listed for the beta emissions, the average beta particle energy is 233 keV.

External Radiation: The specific gamma-ray constant for samarium-153 is 0.46 R/mCi-hr at 1 cm (1.24x10-5 mSv/MBq- hr at 1 Meter). The half-value thickness of lead (Pb) for samarium-153 is approximately 0.10 mm. The use of 1 mm of lead will decrease the external radiation exposure by a factor of approximately 1,000. QUADRAMET® should be stored in a lead-shielded container and frozen until use. Radioactive decay factors to be applied to the stated value for radioactive concentration at calibration are given in Table 2. All radioactivity is calibrated to the reference date and time on the vial.

TABLE 2 - SAMARIUM-153 PHYSICAL DECAY CHART, HALF-LIFE 46.3 HOURS (1.93 DAYS)

Time (hour)* Factor Time (hour)* Factor
-48.0 2.05 +1.0 0.99
-36.0 1.71 +2.0 0.97
-24.0 1.43 +3.0 0.96
-20.0 1.35 +4.0 0.94
-16.0 1.27 +6.0 0.91
-12.0 1.20 +8.0 0.89
-8.0 1.13 +12.0 0.84
-6.0 1.09 +16.0 0.80
-4.0 1.06 +20.0 0.74
-3.0 1.05 +24.0 0.70
-2.0 1.03 +36.0 0.58
-1.0 1.02 +48.0 0.49
*Time = hours before (-) or after (+) calibration

Last updated on RxList: 10/8/2008


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