An investigation of aspects of radiochemical purity of 99mTc-labelled human serum albumin nanocolloid

Abstract

Background Nanocolloidal human serum albumin radiolabelled with 99mTc provides a diagnostic radiopharmaceutical for sentinel node lymphoscintigraphy. NanoHSA (Nanotop), a commercially available kit, enables the simple preparation of this radiopharmaceutical via reconstitution with pertechnetate eluted from a generator. Thin-layer chromatography is widely used for determining radiochemical purity in clinical nuclear medicine. Quality control methods recommended by the manufacturer were sometimes reported to yield variable results. Therefore, we proposed and evaluated three alternative thin-layer chromatography methods for the quality control of [99mTc]Tc-NanoHSA from a commercially available kit. Results The radiochemical purity of [99mTc]Tc-NanoHSA determined with all methods was reproducible and met the requirements of the SPC and the European Pharmacopoeia (≥ 95%). Our quality control using iTLC-SG chromatographic paper in methyl ethyl ketone mobile phase identified only free pertechnetate as impurity, resulting in > 99% RCP. The quality control using iTLC-SG in 85% methanol or iTLC-SA in 0.9% NaCl identified an additional small fraction of a hydrophilic impurity, resulting in 95–97% RCP. Glucose was identified as a potential 99mTc-carrying hydrophilic species contributing to hydrophilic impurities. Conclusion Our quality control of [99mTc]Tc-NanoHSA with non-polar mobile phase tended to underestimate the amount of hydrophilic impurities, although without compromising the final quality of the radiopharmaceutical. Alternative TLC methods using aqueous mobile phases enabled a more accurate determination of hydrophilic impurities.

A dentist’s perspective on scintigraphy about its applications as a diagnostic tool for a myriad of diseases affecting oral health

“…A variety of colloidal and soluble tracers have been used over the years for lymph studies. 16 Incorporating radioactive nuclide has made it possible to identify the sentinel node before surgery and additional benefit will be there for surgical team because they may validate external sampling techniques by simply listing the numerous lymph nodes found through a tiny incision thanks to the intra operative use of gamma probe detectors. These methods give a large improvement in sentinel node identification accuracy.…”

Challenges in Preparation of Albumin Nanoparticle-Based Radiopharmaceuticals

“…There is disagreement about the need for the RCP testing of licensed products, such as 99m Tc-HSA-NC [ 59 ]. Thin-layer chromatography is commonly used [ 18 , 60 ]. For non-licensed products, including those prepared outside the manufacturer’s directions for a licensed product, RCP must be tested prior to release.…”

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“…Liquid chromatography methods are widely used to purify radiopharmaceuticals in clinical and preclinical trials [28]. It is assumed that the radiochemical purity of the trace, understood as the proportion of the activity of the tag to the activity of other radionuclides in the preparation, should be 98-99%.…”