Breakdown Significance of MAA in a Syringe and Vial Post Compounding

Objectives: The prices of Macroaggregated Albumin (MAA) vials have become more expensive, making it more affordable to order unit doses from commercial pharmacies. The objective of this study is to determine if there is a difference in quality control (QC) results when comparing commercially drawn unit doses that have the potential to sit for 6 hours versus radiopharmacy prepared doses drawn directly from vials at the time of injection. When doing QC, a minimal amount of free TcO₄^- and hydrolyzed reduced (HR) TcO₄^- is preferred to ensure that there is a higher amount of technetium bound to the MAA particles.

Methods: QC is done on every compounded kit to make sure that the diagnostic radiopharmaceutical is suitable to administer to the patient. QC consists of a radiochemical quality test, a radionuclide quality test, a chemical impurity test, as well as a pH test. After the 15 minutes’ incubation time for the compounded MAA kit, seven syringes are initially drawn up. To mimic commercially drawn unit doses, six syringes were drawn up for each hour until expiration (time 0-6 hours). A seventh syringe is drawn up to indicate time zero for the immediate QC results of the kit. Every hour, radiochemical QC is done on one of the six syringes and a new sample is drawn up from the MAA vial. Radiochemical quality of the radiopharmaceutical is how much radioactivity in the right chemical form is present in the radiopharmaceutical. Radiochemical quality is evaluated by using chromatography strips designated for Tc99m-MAA. The chromatography test shows what percent of free TcO₄^- and hydrolyzed reduced TcO₄^- there is in the compounded kit; ultimately giving you the labeling efficiency. Radionuclide quality test is how much of the radionuclide activity desired there is compared to the total amount of radioactivity of the source. The source being Mo-99 from the Molybdenum generator and the desired radionuclide is Tc-99m. This is only done once for this research right away at time zero when the 15 minute incubation period is over. The ratio should be less than 0.15 microcuries of Mo-99 per millicuries of Tc-99m. Chemical impurity test is testing to see how much aluminum residual in the Tc-99m eluate from the generator, if there is too much aluminum in the eluate it causes a decrease in binding efficiency. Another test is done to evaluate the pH of the radiopharmaceutical that is administered to the patient. Testing the pH is done simply by using pH paper. A pH out of the range of 4.75-7.5 is not acceptable to administer to the patient. Both of these tests are done once initially at time zero and only need to be done once for this research.

Results: Multiple trials were done on five different compounded MAA kits. The lowest QC result was 98.7% from the syringes and the lowest QC result for the vial is 98.8%. There was no correlation of more breakdown of MAA with time, meaning that QC results did not differ as the time of expiration of the kit progressed.

Conclusions: Looking at the results, there is no significant difference in QC data that would lead to the assumption that the breakdown of MAA is greater in a syringe compared to a vial. Ordering unit doses could save the hospital money and therefore this institution will continue to order unit doses from commercial pharmacies without the concern of HR TcO₄^- or free TcO₄^- being a problem. FIGURES/IMAGES:

REFERENCES: Loveless VS. Quality Control of Radiopharmaceuticals. Fundamentals of Nuclear Pharmacy. 2009; XV:151-174. doi:10.1007/0-387-21702-9_8.