Iodixanol

Usage

Iodixanol is a non-ionic, water-soluble, radiographic contrast medium used to enhance the visibility of internal organs and structures during radiological procedures. It belongs to the pharmacological classification of non-ionic iodinated contrast media. The mechanism of action involves attenuating X-rays as they pass through the body. This allows body structures containing iodine to be delineated in contrast to surrounding tissues.

Alternate Names

Iodixanol is also known by the brand names Visipaque and Visipaque RediFlo Cartridge.

How It Works

Pharmacodynamics: Iodixanol exerts its effect by increasing the radiodensity of blood and other fluids, thereby enhancing the contrast between these fluids and surrounding tissues during imaging procedures like CT scans, angiography, and venography.

Pharmacokinetics:

• Absorption: Administered intravenously or intra-arterially. Not administered orally.
• Distribution: Distributes rapidly into the extracellular space. Does not cross the intact blood-brain barrier.
• Metabolism: Not metabolized.
• Elimination: Excreted primarily unchanged by the kidneys via glomerular filtration, with a half-life of approximately 2 hours in individuals with normal renal function. A small amount is excreted in feces.

Mode of Action: Iodixanol does not bind to receptors or inhibit enzymes. Its primary mechanism involves absorbing X-rays, creating a difference in attenuation between the contrast-filled structures and surrounding tissues.

Dosage

Standard Dosage

Adults:

• CECT (Head and Body): 75-150 mL bolus followed by 100-150 mL infusion (270 mgI/mL or 320 mgI/mL), not to exceed 150 mL total.
• Excretory Urography: 1 mL/kg (270 mgI/mL or 320 mgI/mL), not exceeding 100 mL.
• Venography: 50-150 mL per lower extremity (270 mgI/mL), not exceeding 250 mL.

Children (1-12 years):

• CECT or Excretory Urography: 1-2 mL/kg (270 mgI/mL), not exceeding 2 mL/kg.

Children (over 12 years): Dosages are generally the same as for adults.

Special Cases:

• Elderly Patients: Start at the lower end of the dosing range due to potential age-related decline in renal function. Monitor renal function.
• Patients with Renal Impairment: Use with caution. Close monitoring is necessary as iodixanol is primarily excreted by the kidneys. Formal dose adjustment studies are limited.
• Patients with Hepatic Dysfunction: Use with caution although no formal dose adjustments are generally required.
• Patients with Comorbid Conditions: Careful assessment and monitoring are necessary, particularly in patients with cardiovascular disease, diabetes, thyroid dysfunction, or a history of allergic reactions to contrast media.

Clinical Use Cases: Dosage recommendations are provided above for the indicated clinical uses (CECT, excretory urography, venography). Iodixanol is not indicated for intrathecal use. Its use in other clinical settings like intubation, surgical procedures, mechanical ventilation, ICU use, and emergency situations should be based on the specific procedure and patient needs, guided by clinical judgment and product information.

Side Effects

Common Side Effects:

• Injection site reactions (pain, warmth)
• Nausea, vomiting
• Headache, dizziness
• Changes in taste or smell
• Skin rash, itching

Rare but Serious Side Effects:

• Severe allergic reactions (anaphylaxis, difficulty breathing, swelling)
• Renal failure
• Thyroid dysfunction (especially in neonates and young children)
• Cardiovascular events (e.g., arrhythmias, cardiac arrest)
• Neurological effects (e.g., seizures, encephalopathy)

Contraindications

• Hypersensitivity to iodixanol or its components
• Intrathecal administration

Drug Interactions

• Metformin: Increased risk of lactic acidosis in patients with renal impairment.
• Other nephrotoxic drugs: Increased risk of renal impairment.
• Interleukin-2: Increased risk of delayed reactions.
• Beta-blockers and other antihypertensives: May impair the ability to treat hypotension related to iodixanol administration.

Pregnancy and Breastfeeding

• Pregnancy: Iodixanol should be used during pregnancy only if clearly needed. Monitor neonatal thyroid function after exposure during late pregnancy.
• Breastfeeding: While the amount of iodine in breast milk after iodixanol administration is small, a lactating woman may consider interrupting breastfeeding and discarding milk for 10 hours to minimize infant exposure.

Drug Profile Summary

• Mechanism of Action: Enhances radiographic contrast by attenuating X-rays.
• Side Effects: Nausea, vomiting, headache, injection site reactions, allergic reactions, renal failure, thyroid dysfunction (in young children).
• Contraindications: Hypersensitivity, intrathecal use.
• Drug Interactions: Metformin, nephrotoxic drugs, interleukin-2, beta-blockers.
• Pregnancy & Breastfeeding: Use with caution; monitor neonatal thyroid function.
• Dosage: See detailed section above.
• Monitoring Parameters: Renal function, thyroid function (in neonates and young children), vital signs, allergic reactions.

Popular Combinations

Iodixanol is typically used alone as a contrast agent. It may be used in conjunction with saline flush solutions during administration.

Precautions

• Adequate hydration before and after administration is crucial, especially in patients at risk for renal impairment.
• Monitor renal and thyroid function (especially in neonates and children).
• Have emergency equipment and personnel readily available to manage potential allergic reactions.

FAQs (Frequently Asked Questions)

Q1: What is the recommended dosage for Iodixanol?

A: Please refer to the detailed dosage section above for specific recommendations for various procedures, age groups, and special populations.

Q2: What are the major contraindications for Iodixanol?

A: Iodixanol is contraindicated in patients with a history of hypersensitivity to the drug or its components. It should never be administered intrathecally.

Q3: What are the most common side effects of Iodixanol?

A: Common side effects include injection site reactions (pain, warmth), nausea, vomiting, headache, dizziness, and alterations in taste or smell.

Q4: How is Iodixanol eliminated from the body?

A: Iodixanol is primarily eliminated unchanged through the kidneys via glomerular filtration.

Q5: Can Iodixanol be used in pregnant or breastfeeding women?

A: Iodixanol should be used with caution in pregnant women, and only if the benefits outweigh the potential risks to the fetus. For breastfeeding mothers, consider interrupting breastfeeding for 10 hours and discarding expressed milk to minimize infant exposure.

Q6: What are the signs of a severe allergic reaction to Iodixanol?

A: Signs of a severe allergic reaction can include difficulty breathing, swelling of the face, lips, or throat, hives, and a drop in blood pressure. Seek immediate medical attention if these occur.

Q7: How should Iodixanol be administered?

A: Iodixanol should be administered intravascularly (intravenously or intra-arterially) by or under the supervision of a healthcare professional trained in its use.

Q8: Does Iodixanol interact with other medications?

A: Yes, iodixanol can interact with certain medications like metformin and other nephrotoxic drugs. Inform your physician about all medications you are currently taking.

Q9: What precautions should be taken before administering Iodixanol?

A: Ensure adequate hydration before and after administration, carefully screen for allergies to contrast media, and evaluate renal function. Monitor thyroid function in neonates and young children after administration. Have emergency equipment and trained personnel readily available to manage potential hypersensitivity reactions.