Mibg (123i) Curium Pharma Spain (Iodine (123i) Iobenguane)

Iobenguane I-123 is used in nuclear medicine to image adrenergic tissue and assess sympathetic nervous system disorders.

• Cardiac sympathetic innervation imaging: provides quantitative assessment of myocardial sympathetic nerve integrity, aiding diagnosis of heart failure and arrhythmia risk.
• Pheochromocytoma and paraganglioma detection: localizes catecholamine‑secreting neuroendocrine tumors for surgical planning.
• Neuroendocrine tumor staging: visualizes metastatic disease in tumors that express norepinephrine transporters.

• After intravenous administration, Iobenguane I-123 is taken up by cells expressing the norepinephrine transporter (NET). The iodine‑123 label emits gamma radiation, which is captured by SPECT cameras to produce high‑resolution images of sympathetic nerve distribution in the heart and neuroendocrine tissues. Its rapid clearance from non‑target tissues enhances contrast and allows same‑day imaging. The tracer’s affinity for NET mirrors physiological norepinephrine handling, providing functional insight beyond anatomical imaging.

Iobenguane I-123 may be associated with the following adverse reactions, reported in clinical use.

Common Side Effects

• Nausea: mild to moderate nausea occurring shortly after injection.
• Headache: transient headache reported by some patients.
• Injection site discomfort: mild pain or erythema at the venous access site.
• Flushing or warmth: brief sensation of warmth or skin flushing.

Serious or Rare Side Effects

• Anaphylactic reaction: rare severe allergic response requiring immediate medical intervention.
• Hypotension: sudden drop in blood pressure, particularly in patients with pre‑existing cardiovascular instability.
• Radiation‑induced thyroid dysfunction: potential thyroid damage from iodine exposure, monitored in follow‑up.
• Bone marrow suppression: extremely rare, manifested as cytopenias.

Prior to use, the following precautions should be observed to ensure patient safety and optimal imaging quality.

• Pregnancy: unknown risk; avoid unless the diagnostic benefit outweighs potential fetal exposure.
• Breastfeeding: unknown; consider discontinuing breastfeeding for an appropriate period after administration.
• Thyroid blocking: administer non‑radioactive iodine when necessary to reduce thyroid uptake of free iodine‑123.
• Renal impairment: assess renal function as reduced clearance may increase radiation dose.
• Medication interference: drugs affecting the norepinephrine transporter (e.g., reserpine) can diminish tracer uptake and affect image interpretation.
• Store at 2-8°C: keep refrigerated, protect from light, do not freeze or shake.

Iobenguane I-123 may interact with other agents that influence norepinephrine transport or radiation exposure.

Major Interactions (Avoid)

• Thyroid blocking agents (e.g., potassium iodide): can competitively inhibit iodine uptake, reducing image quality.
• NET inhibitors (e.g., reserpine, guanethidine): markedly decrease tracer accumulation in target tissues.
• Concurrent radiopharmaceuticals: increase cumulative radiation dose and may confound imaging results.

Moderate Interactions (Monitor Closely)

• Beta‑blockers: may alter cardiac sympathetic activity and affect quantitative measurements.
• SNRIs or tricyclic antidepressants: can modestly affect norepinephrine transporter activity, potentially influencing tracer distribution.
• Iodinated contrast media: may transiently affect iodine metabolism; schedule imaging accordingly.