Metabolism of iodine-131 metaiodobenzylguanidine in patients with metastatic pheochromocytoma

Journal Article · Wed Jan 01 04:00:00 EST 1986 · J. Nucl. Med.; (United States)

OSTI ID:5803182

Mangner, T J; Tobes, M C; Wieland, D W; Sisson, J C; Shapiro, B

Iodine-131 metaiodobenzylguanidine ((/sup 131/I)MIBG) is used to image and treat human pheochromocytoma. As part of a pharmacodynamic study of this agent, we have evaluated its excretion and metabolism in nine pheochromocytoma patients undergoing MIGB therapy. Following diagnostic doses of (/sup 131/I)MIBG given prior to therapy, 40 to 55% of the administered radioactivity generally appeared in the urine within 24 hr and 70 to 90% was recovered within 4 days. Reverse-phase high performance liquid chromatography was used to identify radioactive metabolites following therapeutic doses of (/sup 131/I)MIBG. Unaltered (/sup 131/I)MIBG was the major radioactive urinary component found, representing 75 to 90% of the total in all but one of the nine patients examined. The urine samples from the patient, whose rate of urinary excretion was the lowest of the group, contained (/sup 131/I)-m-iodohippuric acid ((/sup 131/I)MIHA) in amounts equal to that of (/sup 131/I)MIBG, as well as small amounts of (/sup 131/I)iodide and (/sup 131/I)-m-iodobenzoic acid ((/sup 131/I)MIBA). Iodine-131 MIHA and (/sup 131/I)iodide were also minor components in the urine samples from the other eight patients. Trace quantities of (/sup 131/I)MIBA and /sup 131/I-4-hydroxy-3-iodobenzylguanidine ((/sup 131/I)HIBG) were also detected in a few of the patient urine samples examined. The 4- to 5-day metabolism profiles varied from patient to patient but were similar for the same patient following therapy doses given 4 mo apart. There was no obvious correlation between the presence of metabolites and the location of the tumors or the plasma or urinary catecholamine levels. Extraction of radioactivity from two pheochromocytomas removed from patients was determined to be primarily MIBG. These studies suggest that (/sup 131/I)MIBG is a rapidly excreted, relatively stable radiopharmaceutical agent.

• Research Organization: Univ. of Michigan Medical Center, Ann Arbor
• OSTI ID: 5803182
• Journal Information: J. Nucl. Med.; (United States), Journal Name: J. Nucl. Med.; (United States) Vol. 1; ISSN JNMEA
• Country of Publication: United States
• Language: English

Related Subjects

550604 -- Medicine-- Unsealed Radionuclides in Therapy-- (1980-)
560171* -- Radiation Effects-- Nuclide Kinetics & Toxicology-- Man-- (-1987)
62 RADIOLOGY AND NUCLEAR MEDICINE
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOLOGICAL MATERIALS
BIOLOGICAL WASTES
BODY FLUIDS
CARBONIC ACID DERIVATIVES
CHEMICAL ANALYSIS
CHROMATOGRAPHY
CLEARANCE
DAYS LIVING RADIOISOTOPES
DISEASES
DRUGS
EVALUATION
EXCRETION
GUANIDINES
INTERMEDIATE MASS NUCLEI
IODINE 131
IODINE ISOTOPES
ISOTOPES
LABELLED COMPOUNDS
MATERIALS
MEDICINE
METABOLISM
METABOLITES
METASTASES
NEOPLASMS
NUCLEAR MEDICINE
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PATIENTS
QUANTITATIVE CHEMICAL ANALYSIS
RADIOCHEMICAL ANALYSIS
RADIOISOTOPES
RADIOLOGY
RADIOPHARMACEUTICALS
RADIOTHERAPY
SEPARATION PROCESSES
TESTING
THERAPY
URINE
WASTES