IOHEXOL
Clinical safety rating: caution
Comprehensive clinical and safety monograph for IOHEXOL (IOHEXOL).
Non-ionic, water-soluble, iodinated contrast agent that increases the radiopacity of vascular structures and body cavities, allowing visualization during radiographic procedures. It does not bind to serum proteins and is rapidly distributed in extracellular fluid.
| Metabolism | Iohexol is not metabolized; it is excreted unchanged by glomerular filtration. |
| Excretion | Primarily renal via glomerular filtration; 90-100% of administered dose excreted unchanged in urine within 24 hours. Less than 2% excreted in feces. Biliary excretion negligible (<1%). |
| Half-life | Terminal elimination half-life approximately 2-3 hours in patients with normal renal function. In patients with severe renal impairment (CrCl <30 mL/min), half-life may be prolonged up to 30-60 hours, necessitating dose adjustment or avoidance. |
| Protein binding | Negligible: <2% bound to plasma proteins (primarily albumin). |
| Volume of Distribution | Approximately 0.25-0.3 L/kg, consistent with distribution primarily in extracellular fluid; minimal intracellular penetration. |
| Bioavailability | Intravenous or intra-arterial administration: 100% bioavailability. Oral or enteral routes: negligible absorption (<1%) if given orally; not used therapeutically by these routes. |
| Onset of Action | Intravenous administration: immediate (within seconds to minutes) due to direct vascular injection, allowing rapid visualization during angiography. Intra-arterial: immediate upon injection. Oral/intrathecal routes: not applicable for onset as iohexol is not administered via these routes for clinical effect. |
| Duration of Action | Intravenous injection: contrast enhancement lasts approximately 5-15 minutes for computed tomography (CT) imaging, depending on dose and cardiac output. Adequate opacification for angiographic procedures persists for several minutes, allowing completion of imaging series. Resorption from intrathecal space (when used for myelography) is slow; residual contrast may persist for hours, but clinical effect (visualization) is immediate after injection. |
Intravenous: 300-370 mg iodine/kg (0.3-0.37 mL/kg of 300 mg I/mL solution) for contrast imaging; typical range 15-150 mL per procedure depending on examination. Intra-arterial: Doses vary by procedure, typically 1-10 mL total. Do not exceed 3 mL/kg total dose.
| Dosage form | SOLUTION |
| Renal impairment | Estimated GFR ≥30 mL/min/1.73m²: No adjustment needed. eGFR 30-59: Use lowest effective dose, ensure hydration, monitor renal function. eGFR <30: Contraindicated for intravascular use; avoid unless essential and no alternative, with extreme caution. Hemodialysis: Not removed efficiently; avoid in non-dialysis patients. |
| Liver impairment | No specific Child-Pugh based adjustments. Use caution in severe hepatic impairment due to potential for altered clearance; monitor renal function as contrast excretion relies on kidneys, not liver. |
| Pediatric use | Intravenous: 1-2 mL/kg of 300 mg I/mL solution (300-600 mg iodine/kg); maximum 3 mL/kg or 150 mL total. Adjust for specific imaging protocol. Not recommended for neonates with GFR <30. |
| Geriatric use | Use lowest effective dose. Pre-hydrate with IV fluids to prevent contrast-induced nephropathy. Assess renal function (eGFR) before administration; consider holding nephrotoxic drugs. Monitor for adverse effects due to potential age-related renal impairment and comorbidities. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for IOHEXOL (IOHEXOL).
| Breastfeeding | Iohexol is excreted into breast milk in very small amounts. The estimated M/P ratio is 0.12. The American College of Radiology suggests that breastfeeding can be continued without interruption after contrast administration, although some clinicians recommend discarding milk for 24 hours post-exposure. |
| Teratogenic Risk | Iohexol is an iodinated contrast agent that crosses the placenta. First trimester exposure carries unknown risk; however, no teratogenic effects have been reported in human studies. Second and third trimester exposure may transiently depress fetal thyroid function due to iodine release, potentially causing neonatal hypothyroidism. |
■ FDA Black Box Warning
WARNING: RISK OF SERIOUS HYPERSENSITIVITY REACTIONS AND CARDIOVASCULAR EVENTS. Serious, life-threatening anaphylactic/anaphylactoid reactions, including death, have occurred. Patients with a history of allergy to iodinated contrast media, asthma, or other allergic disorders are at increased risk. Severe cardiovascular events (e.g., myocardial infarction, arrhythmia) can occur, especially in patients with pre-existing cardiovascular disease.
| Serious Effects |
["History of severe hypersensitivity reaction to iohexol or any iodinated contrast agent","Anuria or known renal failure requiring dialysis"]
| Precautions | ["Hypersensitivity reactions: monitor for signs of anaphylaxis; have emergency equipment available","Acute kidney injury: risk increased in patients with pre-existing renal impairment, diabetes, dehydration, or advanced age; ensure adequate hydration","Thyroid dysfunction: can cause thyroid storm in patients with hyperthyroidism","Intrathecal use: risk of neurotoxicity, including seizures, arachnoiditis, and meningitis","Cardiovascular effects: monitor patients with congestive heart failure, coronary artery disease, or unstable hemodynamics"] |
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| Fetal Monitoring | Monitor maternal renal function before and after administration. In pregnant patients, assess fetal thyroid function (TSH) at birth if iohexol was used in the second or third trimester. Observe for signs of contrast-induced nephropathy or allergic reactions. |
| Fertility Effects | No evidence of impaired fertility in animal studies. No human data on fertility effects. |