Impact of Capsule Type on the Aerodynamic Performances of a Fluticasone Propionate-based Dry Powder under Optimal and Suboptimal Inhalation Flowrates

Nathalie Wauthoz¹, Ismaël Hennia¹, Susana Ecenarro² & Karim Amighi¹

¹Laboratory of Pharmaceutics and Biopharmaceutics, Université libre de Bruxelles (ULB), Boulevard du Triomphe CP207, Brussels 1050, Belgium

² Qualicaps Europe S.A.U., Avenida Monte Valdelatas 4, Alcobendas 28108, Spain

Summary

Background: In the case of capsule-based dry powder inhalers (DPIs), the capsule plays a role not only in the packaging of the formulation, but also in the powder aerosolisation and the drug dispersion from the carrier during inhalation. Previous studies were performed on low drug-dosage dry powders using formoterol fumarate dihydrate (12 µg/24 mg). In the present study, the aim was to evaluate the capsule impact in a higher drug-dosage dry powder using fluticasone propionate (250 µg/25 mg). Methods: This study evaluated the impact of different capsules (Quali-G^TM–I and Quali-V^®-I from Qualicaps^®, and Vcaps^® and Vcaps^®Plus from Capsugel^®) on the delivered dose (DD), fine particle dose (FPD) and capsule retention of a fluticasone propionate-lactose ternary blend using the Axahaler^® DPI under optimal (i.e. 100 L/min) and suboptimal airflows. Results: Under optimal airflow, gelatin capsules (Quali-G-I) showed significantly lower DDs and FPDs than all hypromellose (HPMC) capsules (i.e. Quali-V-I, Vcaps and Vcaps Plus), without significant differences between the HPMC capsules (p < 0.05 and p > 0.05, one-way ANOVA, respectively). However, the thermal-gelled HPMC capsules (Vcaps Plus) showed a significantly higher capsule retention than the cold-gelled HPMC (Quali-V-I and Vcaps) and gelatin capsules (p < 0.05, one-way ANOVA). At a suboptimal airflow which is commonly generated by patients (i.e. 60 L/min), Quali-V-I and Vcaps showed a lower difference in FPD in comparison with those obtained at 100 L/min than Quali-G-I and Vcaps Plus. Conclusion: The best aerodynamic performances were obtained from cold-gelled HPMC capsules, under both optimal and suboptimal airflows.