iobenguane

MIBG is absorbed by and accumulated in granules of adrenal medullary chromaffin cells, as well as in pre-synaptic adrenergic neuron granules. The process in which this occurs is closely related to the mechanism employed by norepinephrine and its transporter in vivo.{{cite book | vauthors = Beylergil V, Perez JA, Osborne JR | veditors = Hamblin MR, Avci P, Gupta GK |title=Imaging in dermatology |date=2016 |location=London |isbn=978-0-12-802838-4 |chapter=Molecular Imaging of Merkel Cell Carcinoma | pages = 467–470 | doi = 10.1016/B978-0-12-802838-4.00033-9 |quote=Metaiodobenzylguanidine (MIBG) is a radiolabeled analogue of guanethidine that enters the cells via the norepinephrine transporter and is either stored in the cytoplasm or in secretory granules|chapter-url=https://www.sciencedirect.com/science/article/pii/B9780128028384000339}}{{cite book | vauthors = Davidoff AM | veditors = Holcomb GW, Murphy JP, Ostlie DJ |title=Ashcraft's pediatric surgery |date=2010 |publisher=Saunders/Elsevier |location=Philadelphia |isbn=978-1-4160-6127-4 |edition=5th |chapter=Neuroblastoma | pages = 872–894 | doi = 10.1016/B978-1-4160-6127-4.00068-9 |quote=Metaiodobenzylguanidine (MIBG) is transported to and stored in the distal storage granules of chromaffin cells in the same way as norepinephrine.|chapter-url=https://www.sciencedirect.com/science/article/pii/B9781416061274000689}} The norepinephrine transporter (NET) functions to provide norepinephrine uptake at the synaptic terminals and adrenal chromaffin cells. MIBG, by bonding to NET, finds its roles in imaging and therapy.

Less than 10% of the administered MIBG gets metabolized into m-iodohippuric acid (MIHA), and the mechanism for how this metabolite is produced is unknown.{{cite web |title=Iobenguane |url=https://go.drugbank.com/drugs/DB06704#metabolism |website=DrugBank Online |access-date=19 August 2021}} from {{cite journal | vauthors = Wishart DS, Feunang YD, Guo AC, Lo EJ, Marcu A, Grant JR, Sajed T, Johnson D, Li C, Sayeeda Z, Assempour N, Iynkkaran I, Liu Y, Maciejewski A, Gale N, Wilson A, Chin L, Cummings R, Le D, Pon A, Knox C, Wilson M | display-authors = 6 | title = DrugBank 5.0: a major update to the DrugBank database for 2018 | journal = Nucleic Acids Research | volume = 46 | issue = D1 | pages = D1074–D1082 | date = January 2018 | pmid = 29126136 | pmc = 5753335 | doi = 10.1093/nar/gkx1037 | author1-link = David S. Wishart }}

{{Anchor|MIBG scan|Diagnostic imaging|Imaging}}

{{Redirect|MIBG scan|the MIBI scan|Technetium (99mTc) sestamibi}}

File:Pheochromocytoma Scan.jpg seen as dark sphere in center of the body (it is in the left adrenal gland). Image is by MIBG scintigraphy, with radiation from radioiodine in the MIBG. Two images are seen of the same patient from front and back. Note dark image of the thyroid due to unwanted uptake of iodide radioiodine from breakdown of the pharmaceutical, by the thyroid gland in the neck. Uptake at the side of the head are from the salivary glands. Radioactivity is also seen in the bladder, from normal renal excretion of iodide.]]

MIBG concentrates in endocrine tumors, most commonly neuroblastoma, paraganglioma, and pheochromocytoma. It also accumulates in norepinephrine transporters in adrenergic nerves in the heart, lungs, adrenal medulla, salivary glands, liver, and spleen, as well as in tumors that originate in the neural crest. When labelled with iodine-123 it serves as a whole-body, non-invasive scintigraphic screening for germ-line, somatic, benign, and malignant neoplasms originating in the adrenal glands. It can detect both intra and extra-adrenal disease. The imaging is highly sensitive and specific.{{cite book | vauthors = Vlachou FJ |chapter= SPECT in Adrenal Glands | title= Imaging in Clinical Oncology | veditors = Gouliamos AD, Andreou JA, Kosmidis PA |date=2018 |publisher=Springer |location=Cham |isbn=978-3-319-68872-5 |page=481 |chapter-url=https://books.google.com/books?id=K1dxDwAAQBAJ&pg=PA481 |language=en |doi=10.1007/978-3-319-68873-2_70| s2cid = 52922868 }}{{cite journal | vauthors = Taïeb D, Hicks RJ, Hindié E, Guillet BA, Avram A, Ghedini P, Timmers HJ, Scott AT, Elojeimy S, Rubello D, Virgolini IJ, Fanti S, Balogova S, Pandit-Taskar N, Pacak K | display-authors = 6 | title = European Association of Nuclear Medicine Practice Guideline/Society of Nuclear Medicine and Molecular Imaging Procedure Standard 2019 for radionuclide imaging of phaeochromocytoma and paraganglioma | journal = European Journal of Nuclear Medicine and Molecular Imaging | volume = 46 | issue = 10 | pages = 2112–2137 | date = September 2019 | pmid = 31254038 | pmc = 7446938 | doi = 10.1007/s00259-019-04398-1 | doi-access = free }}

Iobenguane concentrates in presynaptic terminals of the heart and other autonomically innervated organs. This enables the possible non-invasive use as an in vivo probe to study these systems.{{cite journal | vauthors = Das S, Gordián-Vélez WJ, Ledebur HC, Mourkioti F, Rompolas P, Chen HI, Serruya MD, Cullen DK | display-authors = 6 | title = Innervation: the missing link for biofabricated tissues and organs | journal = npj Regenerative Medicine | volume = 5 | issue = 1 | pages = 11 | date = December 2020 | pmid = 32550009 | pmc = 7275031 | doi = 10.1038/s41536-020-0096-1 | doi-access = free }}{{cite journal | vauthors = Sisson JC, Shapiro B, Meyers L, Mallette S, Mangner TJ, Wieland DM, Glowniak JV, Sherman P, Beierwaltes WH | display-authors = 6 | title = Metaiodobenzylguanidine to map scintigraphically the adrenergic nervous system in man | journal = Journal of Nuclear Medicine | volume = 28 | issue = 10 | pages = 1625–1636 | date = October 1987 | pmid = 3655915 | url = https://jnm.snmjournals.org/content/28/10/1625 }}

Alternatives to imaging with ¹²³I-MIBG, for certain indications and under clinical and research use, include the positron-emitting isotope iodine-124, and other radiopharmaceuticals such as ⁶⁸Ga-DOTA and ¹⁸F-FDOPA for positron emission tomography (PET).{{cite journal | vauthors = Bar-Sever Z, Biassoni L, Shulkin B, Kong G, Hofman MS, Lopci E, Manea I, Koziorowski J, Castellani R, Boubaker A, Lambert B, Pfluger T, Nadel H, Sharp S, Giammarile F | display-authors = 6 | title = Guidelines on nuclear medicine imaging in neuroblastoma | journal = European Journal of Nuclear Medicine and Molecular Imaging | volume = 45 | issue = 11 | pages = 2009–2024 | date = October 2018 | pmid = 29938300 | doi = 10.1007/s00259-018-4070-8 | s2cid = 49410438 | doi-access = | url = https://biblio.ugent.be/publication/8567929/file/8567931 | url-access = subscription }}{{cite journal | vauthors = Rufini V, Treglia G, Castaldi P, Perotti G, Giordano A | title = Comparison of metaiodobenzylguanidine scintigraphy with positron emission tomography in the diagnostic work-up of pheochromocytoma and paraganglioma: a systematic review | journal = The Quarterly Journal of Nuclear Medicine and Molecular Imaging | volume = 57 | issue = 2 | pages = 122–133 | date = June 2013 | pmid = 23822989 | url = https://www.minervamedica.it/en/journals/nuclear-med-molecular-imaging/article.php?cod=R39Y2013N02A0122 }} ¹²³I-MIBG imaging on a gamma camera can offer significantly higher cost-effectiveness and availability compared to PET imaging, and is particularly effective where ¹³¹I-MIBG therapy is subsequently planned, due to their directly comparable uptake.{{cite journal | vauthors = Čtvrtlík F, Koranda P, Schovánek J, Škarda J, Hartmann I, Tüdös Z | title = Current diagnostic imaging of pheochromocytomas and implications for therapeutic strategy | journal = Experimental and Therapeutic Medicine | volume = 15 | issue = 4 | pages = 3151–3160 | date = April 2018 | pmid = 29545830 | pmc = 5840941 | doi = 10.3892/etm.2018.5871 | doi-access = free }}{{cite journal | vauthors = Ballinger JR | title = Theranostic radiopharmaceuticals: established agents in current use | journal = The British Journal of Radiology | volume = 91 | issue = 1091 | pages = 20170969 | date = November 2018 | pmid = 29474096 | pmc = 6475961 | doi = 10.1259/bjr.20170969 }}

Side effects post imaging are rare but can include tachycardia, pallor, vomiting, and abdominal pain.

{{see also|Radionuclide therapy}}

MIBG can be radiolabelled with the beta emitting radionuclide ¹³¹I for the treatment of certain pheochromocytomas, paragangliomas, carcinoid tumors, neuroblastomas, and medullary thyroid cancer.{{cite journal | vauthors = Giammarile F, Chiti A, Lassmann M, Brans B, Flux G | title = EANM procedure guidelines for 131I-meta-iodobenzylguanidine (131I-mIBG) therapy | journal = European Journal of Nuclear Medicine and Molecular Imaging | volume = 35 | issue = 5 | pages = 1039–1047 | date = May 2008 | pmid = 18274745 | doi = 10.1007/s00259-008-0715-3 | s2cid = 6884201 | doi-access = }}

Thyroid blockade with (nonradioactive) potassium iodide is indicated for nuclear medicine scintigraphy with iobenguane/mIBG. This competitively inhibits radioiodine uptake, preventing excessive radioiodine levels in the thyroid and minimizing risk of thyroid ablation (in treatment with ¹³¹I). The minimal risk of thyroid cancer is also reduced as a result.{{cite journal | vauthors = Van Vickle SS, Thompson RC | title = 123I-MIBG Imaging: Patient Preparation and Technologist's Role | journal = Journal of Nuclear Medicine Technology | volume = 43 | issue = 2 | pages = 82–86 | date = June 2015 | pmid = 25956690 | doi = 10.2967/jnmt.115.158394 | doi-access = free }}

The dosing regime for the FDA-approved commercial ¹²³I-MIBG product Adreview is potassium iodide or Lugol's solution containing 100 mg iodide, weight adjusted for children and given an hour before injection.{{cite web |title=Drug Approval Package: AdreView (Iobenguane I 123) NDA # 022290 |url=https://www.accessdata.fda.gov/drugsatfda_docs/nda/2008/022290s000TOC.cfm |publisher=U.S. Food and Drug Administration |access-date=19 August 2021 |date=2008}}{{dead link|date=May 2025|bot=medic}}{{cbignore|bot=medic}} EANM guidelines, endorsed by the SNMMI, suggest a variety of regimes in clinical use, for both children and adults.

Product labeling for diagnostic ¹³¹I iobenguane recommends giving potassium iodide one day before injection and continuing five to seven days following.{{cite web | title = Iobenguane Sulfate I 131 Injection Diagnostic package insert. | location = Bedford, MA | publisher = CIS-US, Inc. | date = July 1999 | url = https://www.drugs.com/pro/iobenguane-sulfate-i-131.html | via = Drugs.com }} ¹³¹I iobenguane used for therapeutic purposes requires a different pre-medication duration, beginning 24–48 hours before iobenguane injection and continuing 10–15 days after injection.

Iobenguane I 131, marketed under the trade name Azedra, has had a clinical trial as a treatment for malignant, recurrent or unresectable pheochromocytoma and paraganglioma, and the FDA approved it on July 30, 2018. The drug is developed by Progenics Pharmaceuticals.{{cite web | url = https://azedra.com/ | title = AZEDRA® (iobenguane I 131 | date = July 2018 | publisher = Progenics Pharmaceuticals Inc., a Lantheus company. | location = Billerica, MA | access-date = 2018-08-03 | archive-date = 2019-08-17 | archive-url = https://web.archive.org/web/20190817152629/https://azedra.com/ | url-status = dead }}{{cite web | url = https://www.fda.gov/newsevents/newsroom/pressannouncements/ucm615155.htm | title = FDA approves first treatment for rare adrenal tumors | date = 30 July 2018 | work = U.S. Food and Drug Administration }}{{dead link|date=May 2025|bot=medic}}{{cbignore|bot=medic}}

{{Reflist}}

• {{cite web | title=iobenguane I 131 | website=NCI Drug Dictionary | url=https://www.cancer.gov/publications/dictionaries/cancer-drug }}
• {{cite web | title=Iobenguane I 131 | website=National Cancer Institute | date=15 August 2018 | url=https://www.cancer.gov/about-cancer/treatment/drugs/iobenguanei131}}

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