Mibg (I-123) (Iodine (123i) Iobenguane)

Iobenguane I-123 is used in nuclear medicine imaging of adrenergic tissue‑related conditions.

• Pheochromocytoma and paraganglioma: enables precise localization and staging of catecholamine‑producing tumors.
• Neuroblastoma: assists in detection and assessment of disease extent in pediatric patients.
• Cardiac sympathetic innervation assessment: evaluates myocardial sympathetic nerve function in heart failure or arrhythmia risk stratification.

• Iobenguane I-123 is an analog of norepinephrine that is actively taken up by adrenergic nerve terminals and chromaffin cells via the norepinephrine transporter. Once accumulated, the I-123 isotope emits gamma photons that are captured by a gamma camera, allowing visualization of sympathetic nervous system activity and tumor uptake patterns.

Adverse reactions to Iobenguane I-123 are generally related to the radiopharmaceutical nature of the product and the intravenous administration.

Common Side Effects

• Nausea: mild, transient feeling of stomach upset.
• Flushing: temporary reddening of skin, often at injection site.
• Headache: mild to moderate discomfort following administration.
• Injection site pain: brief soreness or discomfort at the IV site.

Serious or Rare Side Effects

• Allergic reaction: hives, swelling, or anaphylaxis requiring immediate medical attention.
• Radiation‑induced tissue injury: rare localized damage from radiation exposure.
• Severe hypotension: sudden drop in blood pressure after injection.
• Thyroid dysfunction: abnormal thyroid hormone levels due to iodine exposure.

When using Iobenguane I-123, several precautions should be observed to ensure patient safety and product integrity.

• Pregnancy: avoid use unless clearly needed, as fetal radiation exposure is unknown.
• Breastfeeding: discontinue nursing or assess risk, because iodine may be secreted in milk.
• Renal impairment: consider reduced clearance; monitor renal function.
• Concomitant iodine‑containing drugs: evaluate potential interference with imaging results.
• Store at 2-8°C: keep refrigerated, protect from light, do not freeze or shake.

Iobenguane I-123 may interact with certain substances that affect iodine handling or adrenergic pathways.

Major Interactions (Avoid)

• Thyroid hormone therapy: can alter iodine distribution and affect imaging interpretation.
• Sympathetic blockers (e.g., phenoxybenzamine): may reduce tracer uptake in target tissues.

Moderate Interactions (Monitor Closely)

• Iodinated contrast agents: may compete for iodine uptake, potentially diminishing image quality.
• Diuretics: can affect renal clearance of the radiotracer.
• Antidepressants affecting norepinephrine reuptake: may modify tracer dynamics.