Technetium Tc 99m Medronate

INDICATIONS AND USAGE Technetium Tc 99m medronate may be used as a bone imaging agent to delineate areas of altered osteogenesis.

DOSAGE AND ADMINISTRATION After preparation with oxidant-free sodium pertechnetate Tc 99m injection the suggested dose range of technetium Tc 99m medronate injection in the average patient (70 kg) is 370 MBq to 740 MBq (10 mCi to 20 mCi) given intravenously. Imaging post injection is optimal at 1 to 4 hours. The patient dose should be measured by a suitable radioactivity calibration system immediately prior to administration. Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration whenever solution and container permit. Shielding should be utilized when preparing the technetium Tc 99m medronate injection. Radiation Dosimetry The effective half-life was assumed to be the physical half-life for all calculated values. The estimated radiation absorbed doses to an average patient (70 kg) from an intravenous injection of a maximum dose of 740 MBq (20 mCi) of technetium Tc 99m medronate are shown in Table 4 . Table 4 Absorbed Radiation Dose Organ mGy/740 MBq rads/20 mCi Total Body 1.3 0.13 Bone Total 7.0 0.70 Red Marrow 5.6 0.56 Kidneys 8.0 0.80 Liver 0.6 0.06 Bladder Wall 2-hr. void 26.0 2.60 4.8-hr. void 62.0 6.20 Ovaries 2-hr. void 2.4 0.24 4.8-hr. void 3.4 0.34 Testes 2-hr. void 1.6 0.16 4.8-hr. void 2.2 0.22 Method of Calculation: “S” Absorbed Dose per Unit Cumulated Activity for Selected Radionuclides and Organs, MIRD Pamphlet No. 11, 1975

CONTRAINDICATIONS None known.

WARNINGS This class of compounds is known to complex cations such as calcium. Particular caution should be used with patients who have or who may be predisposed to hypocalcemia (i.e., alkalosis). Preliminary reports indicate interference with brain scans using sodium pertechnetate Tc 99m injection which have been preceded by a bone scan using an agent containing stannous ions. This interference may result in false-positive or false-negative brain scans. It is recommended, where feasible, that brain scans precede bone imaging procedures. The biodistribution of technetium Tc 99m medronate may be altered in the presence of high levels of certain cations (iron, calcium, and aluminum). This may result in reduced uptake of radionuclide in the skeleton and increased extraosseal uptake, which may potentially degrade imaging quality. High levels of these cations may be caused by concomitant medications or medical conditions (e.g., iron overload, hypercalcemia, etc.). Most cases were observed after iron infusion. (See PRECAUTIONS, Drug Interactions .)

Drug Interactions The biodistribution of technetium Tc 99m medronate may be altered in the presence of high levels of certain cations (iron, calcium, and aluminum). This may result in reduced uptake of radionuclide in the skeleton and increased extraosseal uptake, which may potentially degrade imaging quality. In patients with high levels of these cations caused by concomitant medications, particularly patients receiving iron infusions, consider performing an imaging study with technetium Tc 99m medronate injection once the cation levels have normalized (e.g., after 3 to 5 half-lives of the cation). (See WARNINGS .)

ADVERSE REACTIONS Several adverse reactions due to technetium Tc 99m medronate have been reported. These were usually hypersensitivity reactions characterized by itching, various skin rashes, hypotension, chills, nausea and vomiting. There have also been rare cases of dizziness and asthenia associated with the use of technetium Tc 99m medronate.

Pregnancy Animal reproduction studies have not been conducted with technetium Tc 99m medronate. It is also not known whether technetium Tc 99m medronate can cause fetal harm when administered to a pregnant woman or can affect reproductive capacity. Technetium Tc 99m medronate should be given to a pregnant woman only if clearly needed.