PT  - JOURNAL ARTICLE
AU  - Loveless, Vivian S.
AU  - Surdock, Christopher P.
AU  - Bhattacharjee, Himanshu
TI  - Evaluation of Zeta-Potential and Particle Size of Technetium <sup>99m</sup>Tc-Sulfur Colloid Subsequent to the Addition of Lidocaine and Sodium Bicarbonate
AID  - 10.2967/jnmt.109.068973
DP  - 2010 Mar 01
TA  - Journal of Nuclear Medicine Technology
PG  - 49--52
VI  - 38
IP  - 1
4099  - http://tech.snmjournals.org/content/38/1/49.short
4100  - http://tech.snmjournals.org/content/38/1/49.full
SO  - J. Nucl. Med. Technol.2010 Mar 01; 38
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.