DRAX EXAMETAZIME
Clinical safety rating: caution
Comprehensive clinical and safety monograph for DRAX EXAMETAZIME (DRAX EXAMETAZIME).
DRAX EXAMETAZIME is a diagnostic radiopharmaceutical composed of technetium-99m (Tc-99m) labeled to exametazime (hexamethylpropyleneamine oxime, HMPAO). It passively diffuses across the blood-brain barrier and is rapidly converted to a hydrophilic complex, which is trapped in brain tissue. Distribution is proportional to regional cerebral blood flow, allowing SPECT imaging of cerebral perfusion.
| Metabolism | The lipophilic Tc-99m exametazime complex is rapidly metabolized in the brain to a hydrophilic form (secondary complex) that is trapped intracellularly. The radiochemical impurity Tc-99m pertechnetate is eliminated via renal excretion. There is no significant hepatic metabolism. |
| Excretion | Renal: 50-65% unchanged; fecal: 35-50% as metabolites; total renal elimination accounts for ~70% of dose, with 30% undergoing biliary excretion. |
| Half-life | Terminal half-life is 6-8 hours; clinical context: allows for daily dosing in imaging studies. |
| Protein binding | 90-95% bound to serum albumin. |
| Volume of Distribution | 0.7-1.2 L/kg; indicates extensive tissue distribution, particularly to brain and liver. |
| Bioavailability | Intravenous: 100%; no oral or other routes used. |
| Onset of Action | Intravenous: 2-5 minutes to cerebral uptake; no other routes used. |
| Duration of Action | Intravenous: adequate brain uptake for 30-60 minutes post-injection; clinical imaging windows up to 4 hours. |
Adult: 5-20 mCi (185-740 MBq) administered intravenously as a single dose for brain imaging; dose is based on patient weight and imaging protocol.
| Dosage form | POWDER |
| Renal impairment | No dose adjustment required; excretion is primarily fecal, and renal impairment does not significantly alter pharmacokinetics. |
| Liver impairment | No specific guidelines for Child-Pugh; use with caution in severe hepatic impairment as metabolism may be altered. |
| Pediatric use | Pediatric: 0.15-0.20 mCi/kg (5.55-7.4 MBq/kg) intravenous, minimum dose 1 mCi (37 MBq); based on body weight and clinical indication. |
| Geriatric use | No specific adjustment; consider reduced renal function with age but no dose modification recommended; monitor for adverse effects. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for DRAX EXAMETAZIME (DRAX EXAMETAZIME).
| Breastfeeding | M/P ratio unknown. Radiopharmaceuticals may be excreted in breast milk. Interrupt breastfeeding for a period based on the half-life (approximately 2 hours) and specific excretion data. Consult institutional guidelines. |
| Teratogenic Risk | DRAX EXAMETAZIME is a radiopharmaceutical. For all trimesters, fetal radiation exposure is dose-dependent but generally low if used as indicated. No specific teratogenic effects are documented in humans; however, theoretical risk exists due to ionizing radiation. Use only if benefits outweigh risks. |
■ FDA Black Box Warning
None. DRAX EXAMETAZIME does not have an FDA black box warning.
| Serious Effects |
["Hypersensitivity to exametazime or any component of the formulation.","Pregnancy (absolute contraindication unless benefit clearly outweighs risk).","Breastfeeding (relative contraindication; must interrupt feeding for 24 hours)."]
| Precautions | ["Radiopharmaceuticals should be used with caution in pregnant women and pediatric patients due to radiation exposure risk.","Breastfeeding should be interrupted and milk discarded for at least 24 hours after administration.","Reconstitution must be performed under aseptic conditions; the product contains no preservatives.","Use within 30 minutes of reconstitution to minimize radiochemical degradation.","Patient hydration should be encouraged to promote renal clearance of unbound radioactivity."] |
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| Fetal Monitoring |
| Monitor maternal vital signs during administration. No specific fetal monitoring required unless prolonged exposure occurs. Ensure appropriate patient hydration and bladder voiding to minimize radiation dose to the mother and fetus. |
| Fertility Effects | No known effects on fertility. Ionizing radiation may theoretically affect gonadal tissue, but with standard diagnostic doses, effects are negligible. |