TECHNETIUM TC 99M SESTAMIBI
Clinical safety rating: caution
Comprehensive clinical and safety monograph for TECHNETIUM TC 99M SESTAMIBI (TECHNETIUM TC 99M SESTAMIBI).
Technetium Tc 99m sestamibi is a cationic lipophilic complex that passively diffuses across cell membranes and accumulates in mitochondria due to the negative mitochondrial membrane potential. It is used as a myocardial perfusion imaging agent to visualize blood flow to the heart muscle.
| Metabolism | Technetium Tc 99m sestamibi is not metabolized; it is excreted unchanged primarily via the hepatobiliary system and kidneys. |
| Excretion | Primarily renal: approximately 33% of injected dose excreted in urine within 8 hours, increasing to about 50% by 24 hours. Hepatic uptake with subsequent biliary excretion accounts for the remainder; fecal elimination is less than 2% of administered dose. |
| Half-life | Terminal elimination half-life: approximately 6 hours (range 4–8 hours) for myocardial clearance. Delayed clearance may occur in patients with hepatic or renal impairment. |
| Protein binding | Approximately 1% bound to plasma proteins (primarily albumin). |
| Volume of Distribution | Vd: 0.3–0.5 L/kg, indicating distribution primarily into well-perfused tissues including myocardium, liver, and skeletal muscle. |
| Bioavailability | Not applicable; administered only via intravenous injection. Bioavailability is 100% by this route. |
| Onset of Action | Intravenous: Myocardial uptake begins within seconds, with peak myocardial counts achieved at approximately 5–10 minutes post-injection; immediate imaging can be performed at 15–30 minutes. |
| Duration of Action | Myocardial retention sufficient for imaging up to 2–4 hours post-injection; redistribution is minimal over time, allowing for same-day stress/rest protocols if imaging is performed within 2–4 hours. |
Myocardial imaging: 740-1110 MBq (20-30 mCi) IV bolus, single dose. Parathyroid imaging: 740-925 MBq (20-25 mCi) IV bolus, single dose.
| Dosage form | INJECTABLE |
| Renal impairment | No dose adjustment required for renal impairment. Not significantly eliminated renally. |
| Liver impairment | No dose adjustment required for hepatic impairment. |
| Pediatric use | Myocardial imaging: 3.7-5.6 MBq/kg (0.1-0.15 mCi/kg) IV, minimum 37 MBq (1 mCi). |
| Geriatric use | No specific dose adjustment; use lowest effective dose considering renal and hepatic function. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for TECHNETIUM TC 99M SESTAMIBI (TECHNETIUM TC 99M SESTAMIBI).
| Breastfeeding | Tc-99m sestamibi is excreted into breast milk. Mean milk-to-plasma ratio is approximately 1.0. The effective dose to a nursing infant from ingesting contaminated milk is estimated at 0.02 mSv per 740 MBq administered to the mother. Advise interruption of breastfeeding for at least 4 hours after administration, or consider temporary cessation of breastfeeding for the day. Pump and discard milk during that period. |
| Teratogenic Risk | Technetium Tc 99m sestamibi is a radiopharmaceutical. The radiation dose to the fetus from typical diagnostic activities (approximately 5 mSv) is below the threshold for deterministic effects (100 mSv), and stochastic risks are low but non-zero, with a lifetime cancer risk increase estimated at 0.1% per 10 mSv. First trimester exposure carries the highest risk of fetal malformations, though the risk is considered minimal at diagnostic doses. Second and third trimester exposure primarily increases lifetime cancer risk. Use only if clearly needed and benefit outweighs risk. |
■ FDA Black Box Warning
No FDA black box warning.
| Serious Effects |
["Known hypersensitivity to technetium Tc 99m sestamibi or any component of the formulation."]
| Precautions | ["Radiopharmaceuticals should be used only by qualified personnel with appropriate licenses.","Risk of hypersensitivity reactions including anaphylaxis.","Radiation exposure may increase the risk of cancer.","Image interpretation may be affected by patient body habitus, motion, or technical factors."] |
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| Fetal Monitoring | Monitor for allergic reactions during administration. Pregnancy status should be verified before administration via serum or urine beta-hCG. Fetal exposure can be estimated by a medical physicist and documented. No specific fetal monitoring is required post-exposure at diagnostic doses. |
| Fertility Effects | No known adverse effects on fertility from diagnostic doses of Tc-99m sestamibi. Radiation doses to the gonads are low (approximately 0.002-0.004 mGy/MBq) and unlikely to impair fertility. |