Preparation of 99m Tc-MAG3: the effect on radiochemical purity of using sodium chloride injection from plastic ampoules that have been exposed to light.
OBJECTIVE
To determine the circumstances under which sodium chloride injection (SCI) that has been exposed to fluorescent light then used to prepare 99m Tc-MAG3 causes low radiochemical purity (RCP).


METHODS
Two brands of SCI in plastic ampoules (Braun and Steri-Amp) and one in glass vials (Drytec) were exposed to light for up to 7 days then used to prepare 99m Tc-MAG3. RCP was measured by liquid chromatography. To study the effect on the labelling reaction, the reconstituted MAG3 kit was analysed before and after boiling and the formation of the 99m Tc-tartrate intermediate was investigated. Exposed water from plastic ampoules was analysed by mass spectrometry.


RESULTS
After no exposure, each brand resulted in high RCP 99m Tc-MAG3 (>94%). Drytec SCI produced high RCP throughout (96.7 +/- 0.3%, n=5, 7 days). The RCP produced by Steri-Amp and Braun fell to 85.2 +/- 5.2% and 93.5 +/- 1.6% after exposure for 2 and 4 days, respectively. The chromatogram before boiling contained peaks corresponding to 99m Tc-tartrate and 99m Tc-pertechnetate. After boiling with unexposed SCI, these were minimal and a 99m Tc-MAG3 peak dominated. After boiling with exposed SCI, 99m Tc-pertechnetate and 99m Tc-MAG3 peaks were present. Measurements on tartrate showed a high level of 99m Tc-tartrate before and after boiling with unexposed SCI but a high level of 99m Tc-pertechnetate after boiling with exposed SCI. Mass spectrometry showed that compounds leach into the solution upon exposure to light.


CONCLUSIONS
Preparing 99m Tc-MAG3 using SCI from plastic ampoules that have been exposed to light causes reduced RCP. Exposure of plastic ampoules to light causes leaching of many compounds into the solution. An unknown leached compound destabilizes the 99m Tc-tartrate intermediate complex.
Radiopharmacy, Department of Pharmacy, The Royal Infirmary of Edinburgh, Little France Crescent, Edinburgh, UK. lynn.beattie@luht.scot.nhs.uk
Lynn A
LA
Beattie
Lesley M
LM
O'Brien
Clinton C
CC
Waight
Natalie Z
NZ
Homer
Ruth
R
Andrew
Alistair M
AM
Millar
D004340:Drug Contamination / Q000517:prevention & control*; D004349:Drug Packaging; D004356:Drug Storage / Q000379:methods*; D007267:Injections / Q000295:instrumentation; D008027:Light; D010969:Plastics; D019275:Radiopharmaceuticals / Q000737:chemistry; D012965:Sodium Chloride / Q000737:chemistry*; D017263:Technetium Tc 99m Mertiatide / Q000138:chemical synthesis*
D010969:Plastics; D019275:Radiopharmaceuticals; D017263:Technetium Tc 99m Mertiatide; D012965:Sodium Chloride