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)

Teerapol Srichana, D. of Pharmaceutical Tech., F. of Pharmaceutical Sci., PSU.
Anthony Brain, Electron Microscope Unit, King's College London, Camden Hill, London, UK
Christopher Marriott, D. of Pharmacy, King's College London, Manresa Road, London, UK
Gary Peter Martin, D. of Pharmacy, King's College London, Manresa Road, London, UK
Corresponding e-mail : srteerap@ratree.psu.ac.th

Published : Chem Pharm Bull 2000, 48(2) : 167-174
Key words : albuterol sulfate, lactose, andersen cascade impactor, X-ray microanalysis, time of flight aerosol beam spectrometry (TOFABS), dry powder aerosols

The purpose of this study was to determine the deposition in vitro of both drug (albuterol sulfate) and carrier (lactose) particles in relation to each other from a dry powder inhaler formulation using an Andersen cascade impactor (ACI) and time of flight aerosol beam spectrometry (TOFABS). In addition, scanning electron microscopy (SEM) combined with X-ray microanalysis was employed to distinguish albuterol sulfate from lactose. Drug particles apparently penetrated deeper into the impactor than lactose particles contained in the formulation. In some certain stages of impactor drug particles were separated from lactose particles. Although the TOFABS cannot distinguish between albuterol sulfate and lactose, the TOF spectra obtained from the Aerosizer would appear to be partly indicative of the interactions which exist between drug and carrier. One symmetrical TOF peak was obtained from drug or lactose alone. The TOF peak of drug was always lower than TOF of lactose. The times obtained for each powder between experiments were highly reproducible and typical of material and particle size. The use of SEM-X-ray microanalysis also enabled some qualitative cha-racterization of shape and state of association of the two components.

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