Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
ISOVUE-250 vs ISOVUE-128
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Iopamidol is a nonionic, water-soluble iodinated radiographic contrast agent that attenuates X-rays, thereby providing contrast enhancement in imaging studies. Its mechanism of action is physical rather than pharmacological, as it does not have inherent biological activity.
Isovue-128 (iopamidol) is a nonionic, water-soluble, radiographic contrast medium that enhances imaging by attenuating X-rays, thereby increasing contrast between vascular structures and surrounding tissues. Its mechanism is based on the high iodine content which absorbs X-rays, allowing visualization of blood vessels and organs during angiography, urography, and CT scans.
Intravascular use for computed tomography (CT) of the head and body,Intrathecal use for lumbar, thoracic, and cervical myelography,Coronary arteriography and ventriculography,Peripheral arteriography,Excretory urography,Visceral angiography
Intravascular use for computed tomography (CT) imaging,Intravenous urography,Intra-arterial angiography (including coronary, peripheral, and cerebral),Ventriculography,Myelography (subarachnoid injection for spinal imaging),Off-label: Arthrography, hysterosalpingography (though not FDA-approved for these)
Intravenous administration of 50-150 m L (12-37 g iodine) for CT imaging; intra-arterial administration of 10-80 m L (2.5-20 g iodine) for angiography; dose depends on procedure and patient weight.
Adult: 50-200 m L (0.5-2.0 m L/kg) intravenously, single dose for contrast-enhanced CT; for angiography, dose and rate vary by procedure.
Terminal elimination half-life: 1.5-2 hours (normal renal function); clinically, half-life prolonged in renal impairment
Terminal elimination half-life is approximately 1.5-2 hours in patients with normal renal function; prolonged in renal impairment (up to 8-10 hours with GFR <30 m L/min).
Iopamidol is not metabolized. It is excreted unchanged by glomerular filtration, primarily via the kidneys. In patients with normal renal function, 90% or more of the administered dose is eliminated in the urine within 24 hours.
Iopamidol is not metabolized and is excreted unchanged almost entirely by the kidneys via glomerular filtration. No hepatic metabolism or significant protein binding occurs.
Primarily renal: 90-95% unchanged in urine within 24 hours; biliary/fecal: <5%
Renal: >95% excreted unchanged in urine via glomerular filtration; fecal/biliary: <5%.
<5% bound; primarily to albumin
Minimal protein binding (<5%), primarily to albumin.
0.2-0.3 L/kg; reflects distribution in extracellular fluid (does not cross intact blood-brain barrier)
Approximately 0.2-0.3 L/kg, reflecting distribution into extracellular fluid.
Intravascular: 100%; oral: negligible (<1%)
Not applicable for oral route (no oral formulation); 100% bioavailability via intravenous or intra-arterial administration.
e GFR <30 m L/min/1.73m²: avoid use or use minimal dose with adequate hydration; e GFR 30-59: consider lowest effective dose and ensure hydration; no specific dose reduction for e GFR ≥60.
GFR <30 m L/min: use lowest feasible dose; GFR <15 m L/min: avoid use unless essential; consider hydration and N-acetylcysteine.
No specific Child-Pugh based dose modifications; use with caution in severe hepatic impairment due to potential contrast-induced nephropathy risk.
No specific Child-Pugh based adjustments; use with caution in severe hepatic impairment due to risk of contrast-induced nephropathy.
Children: 1-2 m L/kg (250-500 mg iodine/kg) intravenously for CT, not to exceed adult dose; adjust for body weight and procedure.
Neonates: 0.5-1 m L/kg IV; Infants/Children: 1-2 m L/kg IV (max 125 m L per dose) for contrast-enhanced CT.
Elderly patients: use lowest effective dose; ensure adequate hydration; monitor renal function closely due to age-related decline and increased risk of nephropathy.
Reduce dose to lowest effective (e.g., 50-100 m L); ensure adequate hydration; monitor renal function pre and post administration.
Intrathecal administration may result in neurotoxicity including seizures, meningitis, and arachnoiditis. Inadvertent intravascular injection during intrathecal administration may cause serious adverse reactions.
Iodinated contrast media including iopamidol are associated with an increased risk of contrast-induced acute kidney injury (CI-AKI) in patients with pre-existing renal impairment, particularly those with diabetes, volume depletion, or concurrent use of nephrotoxic drugs. Strict adherence to hydration protocols and renal monitoring is required.
Do not use for myelography if procedures are contraindicated,Risk of serious adverse reactions in patients with impaired renal function, including acute renal failure,Risk of cardiorespiratory arrest, anaphylactic shock, and other severe allergic reactions,Potential for thyroid storm in patients with hyperthyroidism,Caution in patients with pheochromocytoma, sickle cell disease, and multiple myeloma
Risk of contrast-induced nephropathy (CIN): Monitor renal function before and after administration, ensure adequate hydration, and avoid concurrent nephrotoxic agents.,Severe hypersensitivity reactions (e.g., anaphylaxis, bronchospasm): Have resuscitation equipment available; premedication may be considered for patients with known contrast allergy.,Thyroid dysfunction: Iodinated contrast may induce hyperthyroidism or hypothyroidism; caution in patients with thyroid disease.,Cardiovascular events: In patients with heart failure, coronary artery disease, or pulmonary hypertension, contrast media can cause hemodynamic instability, arrhythmias, or myocardial ischemia.,Neurologic effects: Intrathecal administration may cause seizures, arachnoiditis, or aseptic meningitis; use lowest possible dose and monitor for neurotoxicity.,Extravasation: Risk of tissue necrosis; administer through a secure IV line and monitor injection site.
History of severe allergic reaction to iopamidol or any component of the formulation,Intrathecal administration in patients with thrombophlebitis, infection, or malignancy at the injection site,Severe renal impairment (anuria, oliguria) unless the benefits outweigh the risks,Patients with a history of grand mal seizures, or those on drugs that lower seizure threshold, for intrathecal use
Absolute: Known hypersensitivity to iopamidol, other iodine-containing contrast media, or any component of the formulation.,Absolute: Intrathecal administration in patients with significant thrombophlebitis or infection at the injection site.,Relative: Pre-existing renal impairment (e GFR <30 m L/min/1.73m²) unless benefits outweigh risks; consider alternative imaging.,Relative: Multiple myeloma, pheochromocytoma, sickle cell disease (due to risk of vaso-occlusive events).,Relative: Pregnancy (especially first trimester) unless essential for diagnosis.
No known food interactions. However, ensure adequate hydration before and after the procedure. Avoid alcohol 24 hours prior as it may increase risk of dehydration.
No specific food interactions. However, patients are often advised to maintain adequate hydration. Avoid alcohol consumption for 24 hours before and after the procedure as it may increase risk of dehydration. No dietary restrictions required.
ISOVUE-250 (iopamidol) is an iodinated contrast agent. In pregnant women, exposure to ionizing radiation from procedures involving iodinated contrast should be minimized. Iodinated contrast agents cross the placenta and may produce transient neonatal hypothyroidism if used in the third trimester. However, data from clinical studies are insufficient to determine a definitive teratogenic risk. First trimester exposure has not been associated with major congenital malformations, but caution is warranted due to potential fetal hypothyroidism with prolonged use near term.
Iodinated contrast agents, including iopamidol (ISOVUE-128), are generally considered low risk for teratogenicity in humans based on limited data. In the first trimester, there is a theoretical risk of fetal hypothyroidism due to free iodide, but clinical evidence does not show a significant increase in congenital anomalies. Second and third trimester exposure is associated with transient neonatal hypothyroidism if the agent crosses the placenta, but no structural teratogenic effects are documented. The FDA assigns a Pregnancy Category B for iodinated contrast agents.
Limited data suggest that iopamidol is excreted into human breast milk in very small amounts. The milk-to-plasma (M/P) ratio is not specifically reported for iopamidol, but for similar iodinated contrast agents, the M/P ratio is low (<0.2). The amount of iodine transferred to the infant is negligible and unlikely to cause adverse effects. However, the American College of Radiology and other guidelines recommend that breastfeeding may be continued without interruption after receiving iodinated contrast, although some advise discarding milk for 12-24 hours if the mother is concerned.
Iopamidol is excreted into breast milk in very small amounts. The milk-to-plasma (M/P) ratio is approximately 0.04–0.08 based on limited studies. The absolute dose received by a nursing infant is estimated to be less than 0.01% of the maternal dose, which is clinically insignificant. Therefore, breastfeeding can be continued without interruption, although some experts suggest discarding milk for 24 hours post-administration as a precaution. No adverse effects on the infant have been reported.
Pregnancy does not require dose adjustments for ISOVUE-250. The dose should be based on the diagnostic procedure and patient weight. However, because of potential fetal hypothyroidism risk from free iodide, alternative imaging modalities without iodinated contrast should be considered if possible, especially in the third trimester.
No dosing adjustments are required for iopamidol (ISOVUE-128) during pregnancy based on pharmacokinetic changes. However, because physiological changes in pregnancy (increased plasma volume, increased renal clearance) may affect contrast agent distribution and elimination, the standard dose should be used based on body weight and indication. The lowest effective dose should be administered to minimize fetal exposure. No specific dose modifications are recommended in guidelines.
ISOVUE-250 (iopamidol 51%) is a nonionic, low-osmolality iodinated contrast medium used for angiography, urography, and CT enhancement. In patients with renal impairment (e GFR <30 m L/min), consider N-acetylcysteine prophylaxis and hydration to reduce risk of contrast-induced nephropathy. Monitor for delayed hypersensitivity reactions, which can occur up to 7 days post-administration. Use caution in patients with pheochromocytoma; pre-treat with alpha-blockers. Shellfish allergy is not a contraindication; true iodine allergy is rare. For intrathecal use, avoid concurrent neurotoxic drugs and ensure patient hydration.
ISOVUE-128 (iopamidol) is a nonionic, low-osmolality contrast medium. Pre-warming to body temperature reduces viscosity and improves patient tolerance. Risk of contrast-induced nephropathy (CIN) increases with pre-existing renal impairment; assess renal function (e GFR) prior to administration. Adequate hydration is critical. Monitor for delayed hypersensitivity reactions (up to 7 days). Metformin should be withheld for 48 hours post procedure if renal function is compromised. Have emergency equipment available for anaphylactoid reactions.
Inform your doctor if you have kidney disease, diabetes, or are taking metformin; metformin may need to be stopped temporarily.,Tell your doctor about all allergies, especially to medications or iodine.,You may feel warmth, flushing, or a metallic taste when the contrast is injected; this is normal.,Drink plenty of water before and after the procedure to help flush the contrast from your body.,Report any symptoms like hives, itching, difficulty breathing, or swelling of the face/mouth immediately.,If you are pregnant or breastfeeding, discuss potential risks with your doctor.
Inform your healthcare provider if you have any allergies, especially to contrast media or iodine.,Tell your provider about all medications you take, particularly metformin or any kidney-affecting drugs.,You may be asked to drink extra fluids before and after the procedure to protect your kidneys.,Report any symptoms like hives, itching, difficulty breathing, or swelling of the face/throat immediately.,If you have diabetes and take metformin, your doctor may advise stopping it for 48 hours after the scan.,Sensation of warmth, a metallic taste, or nausea during injection is common and usually resolves quickly.,After the procedure, you can resume normal diet unless directed otherwise.
No interactions on record
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about ISOVUE-250 vs ISOVUE-128, answered by our medical review team.
ISOVUE-250 is a Contrast Media that works by Iopamidol is a nonionic, water-soluble iodinated radiographic contrast agent that attenuates X-rays, thereby providing contrast enhancement in imaging studies. Its mechanism of action is physical rather than pharmacological, as it does not have inherent biological activity.. ISOVUE-128 is a Contrast Media that works by Isovue-128 (iopamidol) is a nonionic, water-soluble, radiographic contrast medium that enhances imaging by attenuating X-rays, thereby increasing contrast between vascular structures and surrounding tissues. Its mechanism is based on the high iodine content which absorbs X-rays, allowing visualization of blood vessels and organs during angiography, urography, and CT scans.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between ISOVUE-250 and ISOVUE-128 depend on the specific clinical indication. These are both Contrast Media agents and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of ISOVUE-250 is: Intravenous administration of 50-150 m L (12-37 g iodine) for CT imaging; intra-arterial administration of 10-80 m L (2.5-20 g iodine) for angiography; dose depends on procedure and patient weight.. The standard adult dose of ISOVUE-128 is: Adult: 50-200 m L (0.5-2.0 m L/kg) intravenously, single dose for contrast-enhanced CT; for angiography, dose and rate vary by procedure.. Dosing should always be individualized based on indication, renal and hepatic function, age, and other patient factors.
No direct drug-drug interaction has been formally documented between ISOVUE-250 and ISOVUE-128 in current clinical databases. However, individual patient risk factors including other medications, organ function, and comorbidities should always be evaluated by a qualified healthcare provider.
The maternal-fetal safety profiles differ. ISOVUE-250 is classified as Category C. ISOVUE-250 (iopamidol) is an iodinated contrast agent. In pregnant women, exposure to ionizing radiation from procedures involving iodinated contrast should be minimized. Iodinated. ISOVUE-128 is classified as Category C. Iodinated contrast agents, including iopamidol (ISOVUE-128), are generally considered low risk for teratogenicity in humans based on limited data. In the first trimester, there is . Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.