A study of drug-carrier interactions in dry powder inhaler formulations using the Andersen cascade impactor, X-ray microanalysis and time of flight aerosol beam spectrometry (TOFABS)

The purpose of this study was to determine the in vitro deposition of both drug (albuterol sulfate) and carrier (lactose) particles in relation to eac h other from a dry powder inhaler formulation using an Andersen cascade imp actor (ACI) and time of flight aerosol beam spectrometry (TOFABS), In addit ion, scanning electron microscopy (SEM) combined with X-ray microanalysis w as employed to distinguish albuterol sulfate from lactose, Drug particles a pparently penetrated deeper into the impactor than lactose particles contai ned in the formulation. In some certain stages of impactor, drug particles were separated from lactose particles, Although the TOFABS cannot distingui sh between albuterol sulfate and lactose, the TOF spectra obtained from the Aerosizer would appear to be partly indicative of the interactions which e xist between drug and carrier. One symmetrical TOF peak was obtained from d rug or lactose alone, The TOF peak of the drug was always lower than the TO F of lactose, The times obtained for each powder between experiments were h ighly reproducible and typical of material and particle size. The use of SE M-X-ray microanalysis also allowed some qualitative characterization of sha pe and state of association of the two components.