In vitro validation of 99mTc-HFA-FP delivered via pMDI-spacer

The purpose of the study was to label Flixotide (fluticasone propionate [FP] with HFA propellant), with technetium-99m and validate that (99m)Tc acts as a suitable marker for FP when delivered via pMDI-spacer. Sodium pertechnetate was mixed with 5 mL of butanone. (99m)Tc was extracted into butanone and transferred into an empty canister. The (99m)Tc lined canister was heated, and the butanone evaporated to dryness. A supercooled commercial Flixotide canister was decrimped, and the contents transferred to the (99m)Tc lined canister and recrimped. The particle size distribution of FP and (99m)Tc from 10 radiolabeled canisters was measured using an Anderson cascade impactor calibrated to 28.3 L/min, and compared to commercial FP. The drug (FP) content of each particle size fraction was measured using ultraviolet spectrophotometry and the (99m)Tc level in each fraction was measured using an ionization chamber. The percentage of particles in the fine particle fraction (<;4.7 microm) and the percentage of (99m)Tc from commercial and radiolabeled canisters were compared. The mean (SD) % FP in the fine particle fraction, before and after label was 43.2 (1.8) % and 43.9 (2.6) %, respectively. The mean (SD) % (99m)Tc in the fine particle fraction was 42.1 (5.1) %. The mean %FP exiting spacer at (<4.7 microm) before labeling was not significantly different from the mean % FP exiting spacer at (<4.7 microm) after labeling (p > 0.05). The mean % (99m)Tc attached to particles at (<4.7 microm) after radiolabeling was not significantly different from the mean % FP levels (p > 0.05). The validation in this study indicates that (99m)Tc can act as a suitable marker for HFAFP, delivered via pMDI-spacer.