Difference in resistance to humidity between commonly used dry powder inhalers: an in vitro study

• Published in: NPJ primary care respiratory medicine Vol. 26; no. 1; p. 16053
• Main Authors: Janson, Christer, Lööf, Thomas, Telg, Gunilla, Stratelis, Georgios, Nilsson, Folke
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 17.11.2016; Nature Publishing Group
• Subjects: 692/700; 692/700/565; Administration, Inhalation; Anti-Asthmatic Agents - administration & dosage; Asthma - drug therapy; Budesonide - administration & dosage; Budesonide, Formoterol Fumarate Drug Combination - administration & dosage; Dry Powder Inhalers; Humans; Humidity; In Vitro Techniques; Internal Medicine; Medicine; Medicine & Public Health; Pneumology/Respiratory System; Primary Care Medicine; Pulmonary Disease, Chronic Obstructive - drug therapy; Thoracic Surgery
• ISSN: 2055-1010; 2055-1010
• DOI: 10.1038/npjpcrm.2016.53

Multi-dose dry powder inhalers (DPIs) are commonly used in asthma and chronic obstructive lung disease (COPD) treatment. A disadvantage is their sensitivity to humidity. In real life, DPIs are periodically exposed to humid conditions, which may affect aerosol characteristics and lung deposition. This study compared DPI aerosol performance after exposure to humidity. Budesonide (BUD) inhalers (Turbuhaler; Novolizer; Easyhaler) and budesonide/formoterol (BUD/FORM) inhalers (Turbuhaler; Spiromax; Easyhaler) were stored in 75% relative humidity (RH) at both ambient temperature and at −0 °C. Delivered dose (DD) and fine-particle dose (FPD) were tested in vitro before and after storage. BUD inhalers: Turbuhaler and Novolizer showed only small decreases (<15%) in FPD in 40 °C/75% RH, whereas FPD for Easyhaler decreased by >60% ( P =0.01) after 1.5 months of storage. Easyhaler also decreased significantly after 6 months of storage in ambient/75%RH by 25% and 54% for DD and FPD, respectively, whereas only small decreases were seen for Turbuhaler and Novolizer (<15%). BUD/FORM inhalers: Turbuhaler and Spiromax DD were unchanged in 40 °C/75% RH, whereas Easyhaler showed a small decrease. FPD (budesonide) decreased for Turbuhaler, Spiromax and Easyhaler by 18%, 10% and 68% (all significant), respectively, at 40 °C/75% RH. In ambient/75%RH, DD was unchanged for all inhalers, whereas FPD (budesonide) decreased for Spiromax (7%, P =0.02) and Easyhaler (34%, ( P <0.01)). There are significant differences in device performance after exposure to humid conditions. A clinically relevant decrease of more than half FPD was seen for one of the inhalers, a decrease that may affect patients’ clinical outcomes. Prescriber and patient knowledge on device attributes are essential to ensure optimal drug delivery to the lungs. Drug therapy: Humidity can affect inhaler performance Humid storage can affect aerosol characteristics of dry powder inhalers used to treat asthma and other respiratory conditions. A team headed by Christer Janson of Uppsala University in Sweden conducted laboratory testing of commonly available inhalers under humid conditions at both ambient and increased temperatures. Different inhalers showed differing resistances to humidity. The fine particle dose delivered by one inhaler decreased by over 50% after storage for six months at ambient temperature and 75% relative humidity, a reduction that could affect clinical outcomes. Although the number of inhalers available is increasing, there are scant data about inhaler humidity resistance, and many healthcare professionals have limited knowledge about handling these devices. The authors maintain it is vital that healthcare providers be properly informed and patients appropriately educated about different inhalers’ attributes.