1. Introduction
Spacers are widely used by patients who have difficulty using metered-dose inhalers(MDI). However, the high cost and need for maintenance are drawbacks of commercial antistatic spacers. Previous studies have used cheap plastic bottles as spacers but require an inconvenient priming process, and controversy exists over whether they are effective due to a lack of experimental data.

2. Methods
The Next Generation Pharmaceutical Impactor (NGI) was used to simulate inhalers' aerosol delivery to various bronchus stages. A 500 mL plastic bottle was used as a spacer without priming and was compared with two commercial antistatic valved holding chambers, Optichamber and Aerochamber. The electrostatic force was added by rubbing the bottle for 10 seconds with a facial tissue. The deposited amount of salbutamol on different stages of bronchus width in the NGI was measured with HPLC.

3. Results
The total amount of salbutamol deposited on experimental airways via the highly static plastic bottle was significantly higher than other antistatic spacer. The plastic bottle delivered significantly more salbutamol than the commercial spacers to the large airways (13.2±0.78 vs. 5.33±0.35 vs. 8.0±2.14, p=0.0273). Similarly, the amount of salbutamol deposited at the small airways was significantly higher with the plastic bottle than with other spacers (56.47±1.89 ?g vs. 25.2±3.73 ?g vs. 32.87±1.66 ?g, p=0.0273).

4. Conclusion
The unprimed electrostatic plastic bottle as a spacer showed better aerosol delivery of MDI than the commercial antistatic valved holding chambers. The higher volume and length factor outweighed the electrostatic nature of the plastic bottle.