Gastrointestinal tract absorption of cationic anticancer drugs and medicines was estimated using whole-body imaging following oral [123I]
MIBG administration. [123I]
MIBG was added to cultures of human embryonic kidney (HEK)293 cells expressing human organic
anion transporting
polypeptide (OATP)2B1,
carnitine/organic
cation transporter (OCTN)1 and OCTN2, and organic
cation transporter (OCT)1, OCT2, and OCT3 with and without
cimetidine (an OCTN and OCT inhibitor) and
L-carnitine (an OCTN inhibitor). Biodistribution analyses and single-photon emission computed tomography (SPECT) imaging in normal and
dextran sodium sulfate (DSS)-induced experimental
colitis mice were conducted using [123I]
MIBG with and without
cimetidine. [123I]
MIBG uptake was significantly higher in HEK293/OCTN1, 2, and OCT1-3 cells than in mock cells. Uptake via OCTN was inhibited by
L-carnitine, whereas OCT-mediated uptake was inhibited by
cimetidine. Biodistribution analyses and SPECT imaging studies showed significantly lower accumulation of [123I]
MIBG in the blood, heart, liver, and bladder in DSS-induced experimental
colitis mice and mice with
cimetidine loading compared with normal mice, whereas significantly higher accumulation in the stomach and kidney was observed after [123I]
MIBG injection. [123I]
MIBG imaging after
oral administration can be used to estimate gastrointestinal absorption in the small intestine via OCTN and/or OCT by measuring radioactivity in the heart, liver, and bladder.