Long-Term In-Vitro Aerosol Performance and Drug Retention of a Cardboard-Based Spacer (MDI PLUS®) Compared with Conventional Spacer Designs

Abstract

Background

Spacers and valved holding chambers improve drug delivery. However, plastic versions are bulky, costly, and susceptible to electrostatic effects. Newer cardboard or portable designs are affordable and convenient, though evidence regarding long-term aerosol performance remains limited.

Methods

This study assessed the durability, drug retention, and aerosol emission performance of a cardboard-based spacer (MDI PLUS®) over 200 repeated actuations. Aerosol emission of salbutamol (Ventolin®, 100 µg/actuation) and beclometasone (Clenil Forte®, 250 µg/actuation) was measured at set intervals using an Andersen cascade impactor (28.3 L/min), determining total emitted dose (TED) and aerodynamic particle size characteristics. Single-puff deposition within the MDI PLUS®, on the pressurized metered dose inhaler (pMDI), and on a user’s hand was also compared with two commercial plastic spacers, AeroChamber Plus® and AeroChamber2go™.

Results

Over 200 uses, MDI PLUS® maintained a stable delivered dose for salbutamol (TED 221–198 µg) and beclometasone (506–532 µg), without significant change in mass median aerodynamic diameter (≈ 3.97–4.45 μm). Salbutamol fine particle dose (FPD) and fraction (FPF) declined non-significantly, from 165 µg/75% to 119 µg/60%, while beclometasone FPD (307–393 µg) and FPF (61–75%) remained largely unchanged. Drug retention within the spacer increased with repeated use across all devices but was significantly lower for MDI PLUS® (p < 0.05) than for either AeroChamber device. Deposition on the pMDI and on the hand was negligible for all devices.

Conclusion

MDI PLUS® showed durable, consistent aerosol performance across repeated use, with lower drug retention supporting its suitability as a reliable long-term spacer.