I-123 MIBG

Generic name: iobenguane sulfate i-123
Dosage form: injection, powder, lyophilized, for solution
Drug class:Diagnostic radiopharmaceuticals

Medically reviewed by Drugs.com. Last updated on Apr 21, 2022.

Disclaimer: This drug has not been found by FDA to be safe and effective, and this labeling has not been approved by FDA. For further information about unapproved drugs, click here.

Description

I-123 MIBG is provided as a freeze-dried, radio-labeled sterile powder. The powder is reconstituted with 2 mL of sterile normal saline. The dose should be measured using a dose calibrator prior to administration. Caution: Radioactive Material. A commonly used name for iobenguane is meta-iodobenzylguanidine or MIBG.

Clinical Pharmacology

Iobenguane or meta-iodobenzylguanidine (MIBG) is a physiological analog of the guanidines, such as guanethidine and phenethylguanidine. In adrenergic nerves, guanidines are believed to share the same transport pathway as norepinephrine and to accumulate in, and displace norepinephrine from, intraneuronal storage granules. Similarly, I-123 MIBG is concentrated in, stored in, and released from chromaffin granules. The retention of I-123 MIBG in the adrenal medulla may be a result of their uptake in adrenergic neurons and subsequent sequestration into chromaffin storage granules. Due to their selective uptake mechanism, I-123 MIBG allows specific detection and localization of neuroendocrine tumors and adrenal medullary hyperplasia. The gamma emissions given off by I-123 MIBG allow detection of adrenergic tumors by scintigraphy. Medullary thyroid carcinoma: Although the mechanism of I-123 MIBG uptake by medullary thyroid carcinoma (MTC) is not completely understood, it has been found that MTC can produce catecholamines (epinephrine and norepinephrine). Therefore, I-123 MIBG could be taken up and stored in catecholamine vesicles of MTC.

Indications and Usage

Iobenguane is indicated as a radioactive isotope diagnosing for adrenomedullary disorders and neuroendocrine tumors.

Tumors, adrenal medulla (diagnosis): I-123 MIBG is used for diagnostic imaging of the adrenal medulla, for the evaluation and localization of intra- and extra-adrenal pheochromocytomas, paragangliomas, and neuroblastomas, as well as for localization of metastatic lesions from these tumors. I-123 MIBG can also be used for confirmation of diagnosis of pheochromocytoma when catecholamine determination tests are unclear.

Tumors, carcinoid (diagnosis): I-123 MIBG scintigraphy is used as screening procedures for suspected carcinoid tumors, especially those of intestinal origin.

Hyperplasia, adrenal medulla (diagnosis): I-123 MIBG is used in the evaluation of the adrenal medulla for disorders such as medullary hyperplasia in patients at risk of developing medullary disease (e.g., multiple endocrine neoplasia [MEN type 2, MEN type 3]).

Carcinoma, thyroid (diagn...