RESUMO
The purpose of this work was to examine the effect of capsule fill weight and drug/carrier blend ratio of fluorescein isothiocyanate [FITC]-Dextran used as a model drug on the aerosolization performance from Spinhaler[TM]. Micronised FITC-Dextran was tumbled with modified alpha-lactose monohydrate in the ratio of 1:25 and 4:22. Factorial design experiments were carried out to test capsule fill weights of 26 and 104 mg for aerosolization using Andersen cascade impactor [ACI]. Powders were characterised in terms of particle size distribution, morphology and thermal properties. Fine particle fraction based on loaded dose [FPF[Total]] was increased significantly from 14.9 to 23.1% when the blend ratio was increased from 1:25 to 4:22 [fill weight of 26 mg]. The Device retention of FIT-Dextran was reduced as the fill weight and /or blend ratio increased. Mass median aerodynamic diameter [MMAD] of FITC-Dextran decreased slightly but significantly [from 3.59 to 3.27micro m] with the increase in blend ratio for the fill weight 26 mg. Therefore the increase in the capsule fill weight and /or drug: carrier blend ratio improves the aerosolization performance. The effect of blend ratio was however greater compared to fill weight