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Effect of probenecid on renal excretion of three renal radiopharmaceuticals at 15 and 30 minutes

Conference · · J. Nucl. Med.; (United States)
OSTI ID:6792728

The authors have developed and reported new renal TC-99m labeled agents (e.g. Tc-R-VII, a complex of Tc-99m and cystine) as potential replacements for I-131-orthoiodohippuran (OIH), which is the only radiopharmaceutical in routine use for evaluation of renal tubular function, but which has distinct limitations. The new agents have better renal uptake and faster excretion than the Tc-99m-DTPA in current use. To test whether Tc-R-VII is tubularly secreted, they studied the effect of the tubular inhibitor probenecid (P) on it, Tc-99m-DTPA, and OIH in male rabbits at 15 and 30 minutes. After i/v administration of buffered probenecid (100 mg/kg) over 20 minutes , or the buffer for control (C) animals, the radiotracer was intravenously injected. Mean urinary excretion as % dose was assayed. At 15 minutes, P showed no inhibition of DTPA excretion (P: 30.42 +- 8.00 and C: 27.5 +- 2.90). However, P inhibited Tc-R-VII excretion by 37%, which was similar to the inhibition demonstrated for OIH (33%). The inhibition for both compounds was significant at P<0.01. At 30 minutes, probenecid affected neither OIH nor DTPA excretion, while TC-R-VII was inhibited by 30%. These findings indicate that while the newly developed Tc-99m compound is secreted by renal tubules is a manner similar to I-131-OIH and has a promise as a renal radiopharmaceutical, the two compounds have some differences in their renal characteristics and require further study to elucidate the transport mechanisms involved.

Research Organization:
V.A. Med. Ctr., Newington, CT
OSTI ID:
6792728
Report Number(s):
CONF-850611-
Journal Information:
J. Nucl. Med.; (United States), Journal Name: J. Nucl. Med.; (United States) Vol. 26:5; ISSN JNMEA
Country of Publication:
United States
Language:
English