Activity in the gastrointestinal tract after administration of bone-seeking radiopharmaceuticals. Experimental studies in mice.
OBJECTIVE
To test the possibility that (radio)activity of non-pertechnetate nature is excreted into the gastrointestinal tract at bone scintigraphy.


METHODS
The distribution of a bone-seeking radiopharmaceutical (99mTc-HDP) was studied in an experimental mouse system by dissecting different organs and assessing their activity with a gamma-counter.


RESULTS
A comparison of the activity of the submandibular glands, which are assumed to accumulate only pertechnetate, and the gastrointestinal tract showed that a significant fraction of the activity excreted into the gastrointestinal tract did not consist of pertechnetate. Part of the excretion took place in the stomach. It was not connected to a specific bone-seeking agent or 99Mo/99mTc generator. Nor did it increase with time between make-up and injection. The excretion of the non-pertechnetate activity was reduced by cimetidine and omeprazole. These gastric-secretion blocking drugs did not reduce excretion of pertechnetate or significantly affect the general distribution of the radiopharmaceutical.


CONCLUSIONS
There is a significant excretion of non-pertechnetate activity in the gastrointestinal tract. Part of this may be caused by excretion of the undegraded radiopharmaceutical by the stomach mucosa.
Cronhjort
M
M
Department of Diagnostic Radiology, Karolinska Hospital, Stockholm, Sweden.
Jonsson
C
C
Nilsson
S O
SO
Garmelius
B
B
Jacobsson
H
H
D000818:Animals; D000897:Anti-Ulcer Agents / Q000494:pharmacology; D001842:Bone and Bones / Q000000981:diagnostic imaging*; D002927:Cimetidine / Q000494:pharmacology; D004064:Digestive System / Q000378:metabolism*; D004164:Diphosphonates / Q000493:pharmacokinetics; D008297:Male; D051379:Mice; D009853:Omeprazole / Q000494:pharmacology; D015609:Organotechnetium Compounds / Q000493:pharmacokinetics; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D013670:Sodium Pertechnetate Tc 99m / Q000493:pharmacokinetics; D013363:Submandibular Gland / Q000378:metabolism; D013669:Technetium Tc 99m Medronate / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D014018:Tissue Distribution
D000897:Anti-Ulcer Agents; D004164:Diphosphonates; D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; C033905:technetium Tc 99m 1,1-diphosphonopropane-2,3-dicarboxylic acid; C024226:technetium Tc 99m hydroxymethylene diphosphonate; D002927:Cimetidine; D013670:Sodium Pertechnetate Tc 99m; D009853:Omeprazole; D013669:Technetium Tc 99m Medronate