Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
ISOVUE-300 vs ISOVUE-250
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Iodinated radiocontrast agent that attenuates X-rays, providing enhanced visualization of vascular structures and body cavities during imaging procedures.
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.
Intravascular administration for radiography (e.g., angiography, urography),Intrathecal administration for myelography,Intracavitary administration for arthrography, hysterosalpingography, etc.
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
Intravenous: 50-150 m L (up to 300 mg iodine/kg) as a bolus or infusion; intra-arterial: 5-40 m L depending on procedure; intrathecal: 8-15 m L. Maximum total iodine dose: 300 mg iodine/kg.
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.
Terminal elimination half-life in patients with normal renal function is approximately 2 hours. In patients with moderate to severe renal impairment (creatinine clearance <30 m L/min), the half-life can be prolonged up to 20–40 hours, requiring dose adjustment.
Terminal elimination half-life: 1.5-2 hours (normal renal function); clinically, half-life prolonged in renal impairment
Not metabolized; excreted unchanged by glomerular filtration.
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.
Primarily renal (glomerular filtration), with >95% of administered dose excreted unchanged in urine within 24 hours. Less than 1% is excreted via bile/fecal route.
Primarily renal: 90-95% unchanged in urine within 24 hours; biliary/fecal: <5%
Iopamidol (active ingredient) is minimally protein bound (<5%), primarily to albumin.
<5% bound; primarily to albumin
Approximately 0.20–0.30 L/kg, indicating distribution primarily within extracellular fluid space; low tissue binding.
0.2-0.3 L/kg; reflects distribution in extracellular fluid (does not cross intact blood-brain barrier)
Not applicable for oral route as it is used only intravascularly or intrathecally; bioavailability is 100% for IV injection and near 100% for intra-arterial and intrathecal administration.
Intravascular: 100%; oral: negligible (<1%)
GFR <30 m L/min: Use with caution; consider lower dose and ensure adequate hydration. GFR <15 m L/min: Avoid use unless essential; post-procedure hemodialysis may be considered. No specific dose reduction formula; clinical judgment advised.
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.
No specific Child-Pugh based dose adjustments; use cautiously in severe hepatic impairment due to altered pharmacokinetics.
No specific Child-Pugh based dose modifications; use with caution in severe hepatic impairment due to potential contrast-induced nephropathy risk.
Weight-based: 1-2 m L/kg (300 mg iodine/m L) intravenously; maximum total dose 300 mg iodine/kg. Adjust for body habitus and procedure.
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.
Elderly patients may have reduced renal function; assess GFR and adjust dose accordingly. Ensure adequate hydration before and after procedure. Monitor for nephrotoxicity and hypersensitivity.
Elderly patients: use lowest effective dose; ensure adequate hydration; monitor renal function closely due to age-related decline and increased risk of nephropathy.
No FDA boxed warning.
Intrathecal administration may result in neurotoxicity including seizures, meningitis, and arachnoiditis. Inadvertent intravascular injection during intrathecal administration may cause serious adverse reactions.
Risk of serious hypersensitivity reactions (including anaphylaxis),Acute kidney injury in patients with pre-existing renal impairment or other risk factors,Thyroid dysfunction (especially in neonates) due to iodine load,Pregnancy and lactation considerations
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
Known hypersensitivity to iopamidol or any components of the formulation,History of severe adverse reaction to iodinated contrast agents
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
No specific food interactions. However, patients are typically advised to avoid solid food for a few hours before the procedure (e.g., 4-6 hours NPO prior to injection) to reduce the risk of aspiration if emesis occurs. Also, ensure adequate hydration: recommend clear liquids (water, juice) unless contraindicated (e.g., pre-procedure fasting for other reasons).
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.
Iodinated contrast agents like Isovue-300 (iopamidol) cross the placenta. First trimester: Avoid unless essential; theoretical risk of fetal hypothyroidism from free iodide. Second/third trimester: Risk of transient neonatal hypothyroidism if high doses used; fetal goiter reported. No teratogenic effects at clinical doses in animal studies.
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.
Iopamidol is excreted into breast milk in small amounts (<1% of maternal dose). M/P ratio not established. Discontinue breastfeeding for 12-24 hours after administration, or pump and discard. Use only if clearly needed.
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.
No specific dose adjustments for pregnancy; use lowest effective dose. Increased plasma volume may slightly dilute contrast, but no dose change recommended. Avoid in patients with impaired renal function or hyperthyroidism.
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.
ISOVUE-300 (iopamidol) is a nonionic, low-osmolality iodinated contrast medium used for intravascular and intrathecal administration. Key pearls: 1) Pre-hydrate patients with normal saline to reduce risk of contrast-induced nephropathy, especially in those with e GFR <30 m L/min/1.73m². 2) Screen for prior allergic-like reactions; consider premedication with corticosteroids (e.g., prednisone 50 mg PO q12h for 3 doses prior) and antihistamines (diphenhydramine 50 mg IV/PO 1 hour before) for history of moderate or severe reactions. 3) Avoid intrathecal use if there is suspicion of elevated intracranial pressure or CSF obstruction. 4) Metformin should be held for 48 hours post-procedure and only resumed after renal function recheck. 5) Have emergency equipment (oxygen, epinephrine, IV access) readily available for treatment of anaphylactoid reactions.
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.
This contrast agent may cause a warm sensation or metallic taste during injection; these sensations are temporary.,Notify the technologist immediately if you experience itching, hives, difficulty breathing, or swelling of the face or throat.,You should drink plenty of fluids (water) before and after the procedure to help clear the contrast from your kidneys unless otherwise instructed.,If you take metformin for diabetes, you may need to stop it for 48 hours after the procedure; your doctor will advise when to restart.,Inform your healthcare provider about any allergies (especially to iodine or contrast media), kidney problems, asthma, or if you are pregnant or breastfeeding.
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.
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-300 vs ISOVUE-250, answered by our medical review team.
ISOVUE-300 is a Contrast Media that works by Iodinated radiocontrast agent that attenuates X-rays, providing enhanced visualization of vascular structures and body cavities during imaging procedures.. 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.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between ISOVUE-300 and ISOVUE-250 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-300 is: Intravenous: 50-150 m L (up to 300 mg iodine/kg) as a bolus or infusion; intra-arterial: 5-40 m L depending on procedure; intrathecal: 8-15 m L. Maximum total iodine dose: 300 mg iodine/kg.. 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.. 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-300 and ISOVUE-250 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-300 is classified as Category C. Iodinated contrast agents like Isovue-300 (iopamidol) cross the placenta. First trimester: Avoid unless essential; theoretical risk of fetal hypothyroidism from free iodide. Second. 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. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.