A Rapid Analytical Method for Measuring Drug Distribution in Aerosols

Abstract

We have developed a rapid analytical method for measuring drug distribution in aerosols. This method utilizes paper chromatography and a cascade impactor system to determine the distribution of nedocromil sodium (Fisons) and a radioactive tracer, technetium-labeled diethylenetriamine pentaacetate (^99mTc-DTPA), in an aerosol generated by a Fisoneb™ nebulizer. Paper chromatography demonstrated that except for Stage 1 of the cascade impactor, which collects the largest particles, more than 93% of the aerosol mixture of nedocromil sodium and ^99mTc-DTPA eluted at the same point. Further, the distribution of ^99mTc-DTPA gamma counts as measured by a cascade impactor and the concentration of nedocromil sodium as measured by densitometry had the same rank order of concentration in the four stages of the cascade impactor. We conclude that this method can rapidly determine the distribution of a drug within a liquid aerosol and validates the potential use of ^99mTc-DTPA as a marker of drug distribution in the respiratory system.