In Vitro Validation of 99m Tc-HFA-FP Delivered via pMDI-Spacer

Abstract

The purpose of the study was to label Flixotide™ (fluticasone propionate [FP] with HFA propellant), with technetium-99m and validate that ^99mTc acts as a suitable marker for FP when delivered via pMDI-spacer. Sodium pertechnetate was mixed with 5 mL of butanone. ^99mTc was extracted into butanone and transferred into an empty canister. The ^99mTc lined canister was heated, and the butanone evaporated to dryness. A supercooled commercial Flixotide™ canister was decrimped, and the contents transferred to the ^99mTc lined canister and recrimped. The particle size distribution of FP and ^99mTc 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 ^99mTc level in each fraction was measured using an ionization chamber. The percentage of particles in the fine particle fraction (<;4.7 µm) and the percentage of ^99mTc 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) % ^99mTc in the fine particle fraction was 42.1 (5.1) %. The mean %FP exiting spacer at (<4.7 µm) before labeling was not significantly different from the mean % FP exiting spacer at (<4.7 µm) after labeling (p > 0.05). The mean % ^99mTc attached to particles at (<4.7 µm) after radiolabeling was not significantly different from the mean % FP levels (p > 0.05). The validation in this study indicates that ^99mTc can act as a suitable marker for HFAFP, delivered via pMDI-spacer.