AMIPAQUE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for AMIPAQUE (AMIPAQUE).
Metrizamide, a non-ionic iodinated contrast agent, attenuates X-rays due to iodine content, enhancing radiographic imaging. It distributes in extracellular fluid and does not cross intact blood-brain barrier; in subarachnoid space, it outlines neural structures.
| Metabolism | Metrizamide is not significantly metabolized; excreted primarily unchanged by the kidneys via glomerular filtration. Approximately 60% is recovered in urine within 24 hours after intrathecal administration. |
| Excretion | Primarily renal excretion via glomerular filtration; approximately 90-95% of the dose is excreted unchanged in urine within 24 hours. Less than 5% is excreted in feces via biliary route. |
| Half-life | Terminal elimination half-life is approximately 2 hours in patients with normal renal function; may be prolonged in renal impairment (up to 20-30 hours in severe renal failure). |
| Protein binding | Less than 5% bound to plasma proteins. |
| Volume of Distribution | 0.2-0.3 L/kg; indicates distribution primarily within extracellular fluid and minimal tissue binding. |
| Bioavailability | Not applicable for oral route (administered intrathecally or intravenously); bioavailability is 100% for intrathecal and intravenous administration. |
| Onset of Action | Following intrathecal administration: immediate opacification of CSF spaces within minutes. For intravenous use: onset of enhancement occurs immediately after injection. |
| Duration of Action | Intrathecal: diagnostic opacification lasts for about 30-60 minutes; CSF levels decline with a half-life of ~2 hours. Intravenous: contrast enhancement persists for 15-30 minutes post-injection. |
200-300 mg iodine/kg body weight intravenously, maximum 60 g iodine per administration.
| Dosage form | INJECTABLE |
| Renal impairment | eGFR <30 mL/min/1.73 m²: contraindicated; eGFR 30-59: use with caution, consider lower dose and ensure adequate hydration. |
| Liver impairment | No specific dose adjustment based on Child-Pugh score; use caution in severe impairment due to risk of nephrotoxicity. |
| Pediatric use | 150-300 mg iodine/kg intravenously; not recommended for neonates with renal impairment. |
| Geriatric use | Reduce dose proportional to age-related decline in renal function; ensure adequate hydration pre- and post-procedure. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for AMIPAQUE (AMIPAQUE).
| Breastfeeding | Contraindicated during breastfeeding. M/P ratio unknown; iodine is excreted into breast milk and may cause neonatal thyroid suppression. |
| Teratogenic Risk | FDA Pregnancy Category D. First trimester: Avoid use; risk of fetal harm. Second/third trimester: Use only if clearly needed; potential for neonatal hypothyroidism from iodine exposure. |
| Fetal Monitoring | Monitor fetal heart rate during administration. Assess maternal thyroid function (TSH, free T4) before and after. Neonatal thyroid function screening (TSH, T4) after delivery. |
■ FDA Black Box Warning
Accidental or unintended intrathecal administration of ionic contrast media can cause severe, permanent neurological injury or death. Only non-ionic contrast agents should be used for myelography.
| Serious Effects |
["Hypersensitivity to metrizamide or any component","Previous adverse reaction to iodine-based contrast media","Clinical conditions that contraindicate lumbar puncture (e.g., increased intracranial pressure, spinal cord compression)"]
| Precautions | ["Risk of neurotoxicity including seizures, especially in patients with history of epilepsy, alcoholism, or on neuroleptic medications","Serious adverse reactions including aseptic meningitis, arachnoiditis, and neurological deficits","Renal impairment may prolong elimination and increase toxicity","Ensure adequate hydration before and after administration"] |
| Food/Dietary | None known. No specific dietary restrictions are required. |
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| Fertility Effects | No known direct effects on fertility. However, use may be restricted in women attempting conception due to teratogenicity. |
| Clinical Pearls | AMIPAQUE (metrizamide) is a non-ionic, water-soluble contrast agent used primarily for myelography and other intrathecal imaging. Ensure adequate hydration before and after procedure to reduce risk of adverse reactions. Monitor for neurotoxicity including seizures, especially in patients with history of epilepsy. Premedication with corticosteroids may reduce risk of allergic reactions. Do not mix with other drugs or solutions; use only the supplied diluent. |
| Patient Advice | Tell your doctor if you have a history of allergies, asthma, or reactions to contrast media. · You may need to drink plenty of fluids before and after the procedure. · Report any headache, nausea, vomiting, or seizures after the procedure. · Avoid strenuous activity for 24 hours after the procedure. · Inform your doctor if you are pregnant or breastfeeding. |