Medicine:Dry-powder inhaler

From HandWiki
Three types of dry powder inhalers: Turbuhaler, Accuhaler and Ellipta devices.

A dry-powder inhaler (DPI) is a device that delivers medication to the lungs in the form of a dry powder. DPIs are commonly used to treat respiratory diseases such as asthma, bronchitis, emphysema and COPD although DPIs (such as Inhalable insulin) have also been used in the treatment of diabetes mellitus.[1]

DPIs are an alternative to the aerosol-based inhalers commonly called metered-dose inhaler (or MDI). The DPIs may require some procedure to allow a measured dose of powder to be ready for the patient to take. The medication is commonly held either in a capsule for manual loading or in a proprietary form inside the inhaler. Once loaded or actuated, the operator puts the mouthpiece of the inhaler into their mouth and takes a sharp, deep inhalation (ensuring that the medication reaches the lower parts of the lungs), holding their breath for 5–10 seconds. There are a variety of such devices. The dose that can be delivered is typically less than a few tens of milligrams in a single breath since larger powder doses may lead to provocation of cough.

Most DPIs rely on the force of patient inhalation to entrain powder from the device and subsequently break-up the powder into particles that are small enough to reach the lungs.[2] For this reason, insufficient patient inhalation flow rates may lead to reduced dose delivery and incomplete deaggregation of the powder, leading to unsatisfactory device performance. Thus, most DPIs have a minimum inspiratory effort that is needed for proper use and it is for this reason that such DPIs are normally used only in older children and adults.

Inhaler Technique and Use

While DPIs are commonly used in the treatment of lung-based disorders, their use requires dexterity to complete the required sequential steps to achieve application of these devices. Incorrect completion of one or more steps in the use of a DPI can substantially reduce the delivery of the administrated medication and consequently its effectiveness and safety. Numerous studies have demonstrated that between 50 and 100% of patients do not use their inhaler devices correctly, with patients often unaware that they are using their inhaled medication incorrectly.[3][4] Incorrect inhaler technique has been associated with poorer outcomes.[4][5]


Some powder inhalers use lactose to:

  1. Carry the fine particles of the active pharmaceutical ingredient (which must be fine to reach its target)
  2. Improve the flow-ability of the powder during manufacturing and to aid handling
  3. Act as a bulking agent
  4. Aid in powder uptake from the device during inhalation and aerosolization

It has been suggested that such lactose may be harmful to lactose intolerant people,[6] and some doctors advise patients not to use lactose containing DPIs[7] to minimize the risk of hypersensitivity reactions.[8]


DPI medication must be stored in a dry place in a temperature of not more than 25 °C (77 °F) and humidity between 40 and 50% in a sealed packaging, since exposure of the powder to moisture degrades the ability of the device to disperse its medication as a fine powder upon inhalation. Some medication also needs photo protection.

See also


  1. "Exubera Prescribing Information". Pfizer. April 2008. 
  2. Finlay, Warren H. (2001). The mechanics of inhaled pharmaceutical aerosols: an introduction. Boston: Academic Press. ISBN 978-0-12-256971-5. 
  3. Vanderman, Adam J.; Moss, Jason M.; Bailey, Janine C.; Melnyk, S. Dee; Brown, Jamie N. (February 2015). "Inhaler Misuse in an Older Adult Population". The Consultant Pharmacist 30 (2): 92–100. doi:10.4140/tcp.n.2015.92. PMID 25695415. 
  4. 4.0 4.1 Gregoriano, Claudia; Dieterle, Thomas; Breitenstein, Anna-Lisa; Dürr, Selina; Baum, Amanda; Maier, Sabrina; Arnet, Isabelle; Hersberger, Kurt E. et al. (2018-12-03). "Use and inhalation technique of inhaled medication in patients with asthma and COPD: data from a randomized controlled trial". Respiratory Research 19 (1): 237. doi:10.1186/s12931-018-0936-3. ISSN 1465-993X. PMID 30509268. 
  5. Maricoto, Tiago; Monteiro, Luís; Gama, Jorge M. R.; Correia-de-Sousa, Jaime; Taborda-Barata, Luís (2018-10-06). "Inhaler Technique Education and Exacerbation Risk in Older Adults with Asthma or Chronic Obstructive Pulmonary Disease: A Meta-Analysis". Journal of the American Geriatrics Society 67 (1): 57–66. doi:10.1111/jgs.15602. ISSN 1532-5415. PMID 30291745. 
  6. Changes in Inhaler Devices for Asthma And COPD – Health – RedOrbit
  7. Milk Proteins and Allergy Medications
  8. Robles, J; Motheral, L (2014). "Hypersensitivity reaction after inhalation of a lactose-containing dry powder inhaler". J Pediatr Pharmacol Ther 19 (3): 206–11. doi:10.5863/1551-6776-19.3.206. PMID 25309152. 

Further reading