Effect of an external resistance to airflow on the inspiratory flow curve

• Published in: International journal of pharmaceutics Vol. 234; no. 1; pp. 257 - 266
• Main Authors: de Koning, J.P, van der Mark, Th.W, Coenegracht, P.M.J, Tromp, Th.F.J, Frijlink, H.W
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 02.03.2002; Elsevier
• Subjects: Administration, Inhalation; Adult; Airway Resistance; Asthma - physiopathology; Biological and medical sciences; Dry powder inhaler; Female; Flow increase rate; General pharmacology; Humans; Inspiratory flow curve; Male; Medical sciences; Nebulizers and Vaporizers; Peak inspiratory flow; Pharmaceutical technology. Pharmaceutical industry; Pharmacology. Drug treatments; Pulmonary Disease, Chronic Obstructive - physiopathology; Pulmonary drug delivery; Resistance to airflow; Respiratory Mechanics - physiology; Dry powder inhaler; Inspiratory flow curve; Flow increase rate; Pulmonary drug delivery; Peak inspiratory flow; Resistance to airflow; Human; Delivery system; Inspiration; Lung disease; Pharmaceutical technology; Respiratory disease; Intrapulmonary administration; Powder; Asthma; Inhalation; Resistance; Air flow; Inhaler; Obstructive pulmonary disease
• ISSN: 0378-5173; 1873-3476
• DOI: 10.1016/S0378-5173(01)00969-3

Inhalation is a convenient way to deliver drugs to the respiratory tract in the treatment of respiratory diseases. For dry powder inhalers (DPI's), the principle of operation is to use the patient-generated inspiratory flow as energy source for emptying of the dose system and the delivery of fine drug particles into the respiratory tract. Resistance to airflow of the inhaler device is a major determinant for the inspiratory flow profile through the dry powder inhaler that can be generated by the patient. Therefore, resistance to airflow is one of the design parameters for DPI's, that could be used to control the inspiratory flow profile, and is one of the parameters to optimise particle deposition in the airways. In this study the effect of resistance to airflow on different parameters of the inspiratory flow curves as generated by healthy subjects, asthmatics and COPD patients was determined. As a result of increased resistance to airflow, the peak inspiratory flow (PIF), the flow increase rate (FIR) and the inhaled volume to reach PIF is decreased. On the other hand, the total inhalation time as well as the 80% dwell time is increased. In general, tuning of the resistance to airflow in the design of a dry powder inhaler may improve the drug deposition in the respiratory tract.