Omnipaque (Iohexol)

Omnipaque is an iodinated contrast medium used to improve imaging of vascular and organ systems.

• CT scan of the head and brain: provides enhanced contrast for detecting lesions, hemorrhage, and tumors.
• Angiography (cardiac, cerebral, peripheral): delineates blood vessels for diagnostic and interventional procedures.
• Urography and intravenous pyelography: highlights urinary tract structures for assessment of obstruction or stones.

• Iohexol is a water‑soluble, non‑ionic iodine compound that absorbs X‑ray photons, increasing attenuation of the X‑ray beam. When injected intravenously, it distributes within the vascular and extracellular spaces, creating a temporary difference in radiodensity between blood‑filled structures and surrounding tissues, thereby improving image contrast for diagnostic radiology.

Adverse reactions to Omnipaque can range from mild to severe and are related to its iodine content and osmolarity.

Common Side Effects

• Warm sensation or flushing: transient feeling of heat during injection.
• Nausea: mild upset stomach occurring shortly after administration.
• Vomiting: occasional emesis following the procedure.
• Headache: brief headache reported by some patients.
• Metallic taste: temporary taste alteration during infusion.
• Mild itching or rash: limited skin irritation.

Serious or Rare Side Effects

• Allergic reaction (anaphylaxis): severe hypersensitivity requiring immediate medical intervention.
• Contrast‑induced nephropathy: acute decline in renal function, especially in patients with pre‑existing kidney disease.
• Cardiovascular collapse: sudden drop in blood pressure or cardiac arrest in rare cases.
• Seizures: neurologic events linked to severe reactions.
• Pulmonary edema: fluid accumulation in lungs due to severe hypersensitivity.
• Hemolysis: rare destruction of red blood cells.

When using Omnipaque, clinicians should observe several safety measures to minimise risk.

• Assess renal function: evaluate serum creatinine and eGFR before administration.
• Screen for iodine allergy: avoid in patients with known hypersensitivity to iodinated contrast.
• Ensure adequate hydration: encourage fluid intake before and after the procedure to reduce nephrotoxicity.
• Review concomitant nephrotoxic drugs: consider alternatives or adjust timing when possible.
• Pregnancy and lactation: use only if diagnostic benefit outweighs potential fetal or infant risk.
• Store at ambient temperature: keep in original container, protect from light and moisture.

Omnipaque may interact with other agents that affect iodine load, renal function, or metabolic balance.

Major Interactions (Avoid)

• Iodine‑containing medications (e.g., potassium iodide): may increase total iodine exposure.
• Nephrotoxic agents (e.g., aminoglycosides, NSAIDs): heighten risk of renal impairment.
• Metformin: risk of lactic acidosis in patients with reduced renal function; hold metformin before and after contrast exposure.

Moderate Interactions (Monitor Closely)

• Beta‑blockers: may mask contrast‑induced hypertension; monitor blood pressure.
• Diuretics: can alter fluid and electrolyte balance; observe renal parameters.
• ACE inhibitors/ARBs: may affect renal perfusion; consider temporary discontinuation.
• Thyroid medications: excess iodine may influence thyroid function tests.
• Calcium channel blockers: monitor for additive vasodilatory effects.