IOPAMIDOL
Clinical safety rating: caution
Comprehensive clinical and safety monograph for IOPAMIDOL (IOPAMIDOL).
Iopamidol is a nonionic, water-soluble radiographic contrast agent that attenuates X-rays by increasing the density of vascular structures and organs, thereby enhancing contrast in imaging studies. It does not have a pharmacological mechanism of action but exerts its effect via physical radiopacity.
| Metabolism | Iopamidol is not metabolized; it is excreted unchanged in the urine via glomerular filtration with negligible protein binding. |
| Excretion | Renal: >90% unchanged; biliary/fecal: <2% |
| Half-life | 2 hours; prolonged in renal impairment (up to 30 hours in anuria) |
| Protein binding | <5% (albumin) |
| Volume of Distribution | 0.3 L/kg; primarily extracellular fluid |
| Bioavailability | IV/IA: 100% (not applicable oral); intrathecal: systemic absorption negligible |
| Onset of Action | IV: immediate (seconds); intra-arterial: immediate; intrathecal: within minutes |
| Duration of Action | IV: 15-30 minutes for contrast imaging; prolonged in renal impairment |
Intravenous or intra-arterial administration; dose varies by procedure (e.g., cerebral angiography: 5-10 mL; coronary arteriography: 3-10 mL per injection; CT: 50-150 mL; adults: up to 200 mL total).
| Dosage form | INJECTABLE |
| Renal impairment | For eGFR 30-60 mL/min: maintain caution; no specific dose reduction. For eGFR <30 mL/min: avoid if possible; if required, use minimum volume necessary, ensure adequate hydration, and consider hemodialysis post-procedure. |
| Liver impairment | No dose adjustment required for hepatic impairment; no Child-Pugh-based modifications established. |
| Pediatric use | Weight-based dosing: 0.5-2.0 mL/kg per injection; maximum total dose not exceeding 4 mL/kg; individualize based on procedure and patient condition. |
| Geriatric use | No specific dose adjustment; consider reduced renal function and ensure adequate hydration to prevent contrast-induced nephropathy. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for IOPAMIDOL (IOPAMIDOL).
| Breastfeeding | Iopamidol is excreted into human breast milk in low concentrations. The milk-to-plasma (M/P) ratio is not well-defined but estimated to be approximately 0.5–1.0 based on similar iodinated contrast agents. The absolute dose ingested by a nursing infant is low (estimated less than 0.1% of maternal dose). Precaution: The American College of Radiology recommends that breastfeeding may be continued without interruption after iopamidol administration, but some sources suggest discarding milk for 24 hours to minimize potential mild gastrointestinal effects or theoretical thyroid suppression. No adverse effects have been reported. |
| Teratogenic Risk | Iopamidol, an iodinated contrast agent, is classified as FDA Pregnancy Category B. In animal studies, no evidence of teratogenicity or fetal harm was observed at doses up to 2.5 times the human dose. However, adequate and well-controlled studies in pregnant women are lacking. Iopamidol crosses the placenta and can cause transient fetal thyroid suppression when administered near term. Theoretical risks of free iodide exposure include neonatal hypothyroidism, particularly with high doses or repeated exposure. Use during the first trimester should be avoided unless essential; if required, limit to lowest diagnostic dose. |
■ FDA Black Box Warning
Risk of serious, life-threatening adverse reactions including anaphylaxis, cardiac arrest, and severe cardiovascular events. Intrathecal administration may cause arachnoiditis, meningitis, or neurologic injury. Not for use in patients with a history of severe allergic reaction to contrast media.
| Serious Effects |
["Absolute: history of severe allergic reaction to iopamidol or any iodinated contrast agent.","Absolute: anuria or known irreversible renal failure.","Relative: concurrent administration of NSAIDs, metformin (risk of lactic acidosis), or nephrotoxic drugs; should be carefully monitored.","Relative: pregnancy (category B) and lactation (use only if clearly needed).","Relative: multiple myeloma or paraproteinemias (risk of renal precipitation)."]
| Precautions | ["Contrast-induced nephropathy: risk increases with pre-existing renal impairment, diabetes, dehydration, and high doses.","Allergic-type reactions: ranging from mild urticaria to anaphylactic shock; premedication may be considered in high-risk patients.","Thyroid dysfunction: can cause hyperthyroidism in patients with latent hyperthyroidism or autonomous thyroid nodules.","Cardiovascular: may precipitate cardiac arrhythmias, hypertension, or hypotension; caution in patients with heart failure or unstable angina.","Intrathecal use: risk of neurotoxicity including seizures, arachnoiditis, and meningitis; avoid in patients with suspected intracranial hemorrhage or spinal block.","Sickle cell disease: may promote sickling and vaso-occlusive events."] |
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| Fetal Monitoring | No specific maternal or fetal monitoring is required for iopamidol alone. However, if used during pregnancy, monitor fetal thyroid function (TSH, FT4) in neonates if exposure occurred near term. In high-risk pregnancies (e.g., preeclampsia, renal impairment), monitor maternal renal function (serum creatinine) and hydration status before and after administration due to risk of contrast-induced nephropathy. Fetal heart rate monitoring is not routine. |
| Fertility Effects | No evidence of impaired fertility in animal studies. Iopamidol has no known direct effect on human fertility. However, radiation exposure from fluoroscopic procedures using iopamidol may have gonadal effects if significant; limit gonadal radiation exposure. |
| Food/Dietary | No specific food interactions. Maintain adequate hydration with water or clear fluids before and after procedure; avoid alcohol before the study as it may worsen dehydration. |
| Clinical Pearls | Iopamidol is a low-osmolality nonionic iodinated contrast medium used for angiography, urography, and CT enhancement. Risk of contrast-induced nephropathy (CIN) is lower with iopamidol than with high-osmolality agents. Pre-hydrate patients with normal saline (1 mL/kg/h for 12 hours pre- and post-procedure) to reduce CIN risk. Metformin should be withheld 48 hours before and after contrast administration in patients with eGFR <30 mL/min/1.73m² to avoid lactic acidosis. Iopamidol can cause delayed hypersensitivity reactions; ensure rescue equipment (epinephrine, antihistamines, corticosteroids) is available. Use lowest possible dose in patients with impaired renal function (eGFR <60). |
| Patient Advice | Inform your doctor if you have any allergies, especially to iodine or contrast agents. · Drink plenty of water before and after the procedure to help flush the contrast from your kidneys unless instructed otherwise. · Report any symptoms like shortness of breath, hives, or swelling of the face/throat immediately. · If you take metformin for diabetes, you may need to stop it 48 hours before and after the scan; your doctor will advise. · You may experience a warm sensation or metallic taste during injection; this is normal and temporary. |