RT Journal Article SR Electronic T1 Evaluation of Zeta-Potential and Particle Size of Technetium 99mTc-Sulfur Colloid Subsequent to the Addition of Lidocaine and Sodium Bicarbonate JF Journal of Nuclear Medicine Technology JO J. Nucl. Med. Technol. FD Society of Nuclear Medicine SP 49 OP 52 DO 10.2967/jnmt.109.068973 VO 38 IS 1 A1 Vivian S. Loveless A1 Christopher P. Surdock A1 Himanshu Bhattacharjee YR 2010 UL http://tech.snmjournals.org/content/38/1/49.abstract AB The use of 99mTc-sulfur colloid lymphoscintigraphy for the determination of lymph flow patterns from a tumor site and localization of the sentinel node has been widely adopted. However, the effects of multiple injections of the radiopharmaceutical can range from mild discomfort to pain. pH-adjusted lidocaine HCl coadministered with 99mTc-sulfur colloid presents a risk of introducing instability of the radiopharmaceutical, which could lead to aggregation, possibly impeding the kinetics of lymphatic drainage from the tumor site. Methods: In the present study, lidocaine pH-adjusted with 4.2%, 6.3%, or 8.4% sodium bicarbonate was added to the 99mTc-sulfur colloid radiopharmaceutical to monitor effects on radiochemical purity, zeta-potential, particle size, and pH. These parameters were then used to evaluate the short-term stability of the preparation. Results: The study revealed that the formulation of lidocaine pH-adjusted with 8.4% sodium bicarbonate added to 99mTc-sulfur colloid demonstrated a similar change in zeta-potential (−4.09 ± 2.90 mV) and particle size (10–330 nm) to that of control filtered 99mTc-sulfur colloid (−5.09 ± 1.68 mV and 11–343 nm, respectively). However, the 4.2% preparation showed a zeta-potential of −3.01 ± 2.24 mV and a particle size range of 10–351 nm. The pH of the 8.4% buffered preparation, at 7.1, was closer to physiologic pH than was the control, at 6.0. The 6.3% pH-adjusted lidocaine–99mTc-sulfur colloid preparation failed radiochemical purity; thus, it was not included in the analysis. Conclusion: Compared with other 99mTc-sulfur colloid test formulations of 4.2% and 6.3% pH-adjusted lidocaine, the 8.4% sodium bicarbonate pH-adjusted lidocaine–99mTc-sulfur colloid preparation, taken as a whole, yielded superior quality-control parameters. This formulation would be an acceptable alternative to the control.