Investigation of Humidity and Electrostatic Charge on Anticholinergic Molecules in Dry Powder Inhalations

Abstract Background: Dry powder inhalers (DPIs) are commonly used for respiratory diseases such as asthma, chronic bronchitis, and chronic obstructive pulmonary disease (COPD). DPIs have many advantages for patients, such as ease of use or rapid delivery to the patient’s lungs. However, they can be very sensitive to environmental conditions such as ambient relative humidity (RH) and electrostatic charge, and therefore the manufacturing process and storage conditions of these pharmaceutical products must be carefully determined. Method: In this study, two different active substances belonging to the anticholinergic family were studied and it was examined how the active substances of the same family might be affected by changing humidity conditions. The change in the amount of delivered active substance to the patient’s lungs as the electric charge accumulated in the capsules was determined. Additionally, the effect of electrical charge of the inhaler device on fine particle dose (FPD) was studied in capsules manufactured with Active Substance-1. Results and Conclusion: This study demonstrated that, with the increase in ambient humidity and aging of the capsule and powder, the FPD of Active Substance-1 and the total mass increased in parallelly. While Active Substance-2 was not affected by the aging of the capsules, it was observed that the FPD value increased with the increase in ambient RH during the manufacturing process.