THE DEPOSITION OF SOLUTION-BASED AND SUSPENSION-BASED AEROSOLS FROM METERED-DOSE INHALERS IN HEALTHY-SUBJECTS AND ASTHMATIC-PATIENTS

This study was carried out to compare the pulmonary deposition of ultr afine and fine particle size aerosols generated by different formulati ons in healthy volunteers and in asthmatic subjects. The two formulati ons used were a Teflon particulate suspension with a mean particle dia meter of 5.76 mu m, and a solution of radiolabel in propellant which g enerated aerosol particles of 2.13 mu m mean diameter. A standard mete red dose inhaler formulation (vapour pressure 444 kPa, chlorofluorocar bon 11 and 12 propellants, ratio 30/70) was utilized for both aerosols . Both formulations were radiolabelled with Tc-99m. Pulmonary depositi on of the aerosols was measured using gamma scintigraphy. The aerosol generated from the solution produced a significantly greater total lun g deposition compared to the suspension aerosol in both asthmatic and healthy subjects: 61 +/- 11%, compared to 17 +/- 5% for healthy subjec ts (p = 0.009), and 59 +/- 17%, compared to 10 +/- 4% in asthmatic sub jects (p = 0.004). The results suggest that propellant-soluble drugs d elivered from metered dose inhalers may offer better airway penetratio n in both normal and asthmatic subjects.