Impact of prolonged use of NSAID (Diclofenac) on 99mTc-MAG3 and 99mTc-DTPA renography

Background

Non-steroidal anti-inflammatory drugs (NSAIDs), such as diclofenac, are globally recognized as the primary choice for alleviating kidney pain and ureteric colic. This study examines the effects of long-term diclofenac administration on renography using two radiopharmaceuticals: 99mTc-mercaptoacetyltriglycine (99mTc-MAG3), which is excreted almost exclusively by the renal tubules, and 99mTc-diethylenetriamine pentaacetic acid (99mTc-DTPA), which is predominantly excreted by glomerular filtration.

Results

Diclofenac administration caused a rightward shift in renograms, indicating delayed renal uptake and clearance for both tracers. For 99mTc-MAG3, the average time to peak activity (Tmax) increased from 2.88 ± 0.3 min (control) to 4.2 ± 0.3 min (treated), while time from peak to 50% activity (T½) rose from 4.16 ± 0.1 min to 5.48 ± 0.5 min. For 99mTc-DTPA, Tmax increased from 4.3 ± 0.4 min to 12.9 ± 2.0 min, and T½ extended from 13.35 ± 1.5 min to 29.75 ± 2.0 min (n = 12; *p < 0.05 for all comparisons). Delayed tracer arrival in the bladder was particularly pronounced with 99mTc-DTPA.

Conclusions

Chronic diclofenac exposure significantly delays Tmax and T½ for both tracers, with a greater impact observed using 99mTc-DTPA. These findings highlight 99mTc-MAG3 as the preferred radiopharmaceutical for renography in settings involving long-term NSAID administration, ensuring accurate and reliable interpretation and minimizing variability associated with radiopharmaceutical selection.