Drug Inhalation Devices and Delivery Systems

Drug Inhalation Devices and Delivery Systems

Drug Inhalation Devices and Delivery Systems Inhalation drug therapy is the primary way to deliver medication locally to the lungs because of its spee...

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Drug Inhalation Devices and Delivery Systems Inhalation drug therapy is the primary way to deliver medication locally to the lungs because of its speed, effectiveness, and minimal systemic side effects. Although once used to extensively treat respiratory conditions such as asthma, recently, inhalation therapy has been acknowledged as an effective route to systemically deliver drugs for other conditions. The development of novel inhalers has improved performance, efficacy, and patient adherence. This discussion is focused on available inhalation devices including new options that enhance drug delivery.1 Pressurized metered dose inhalers (pMDIs) have become the most widely prescribed inhalation devices for pulmonary drug delivery. They can deliver an accurate amount of chemical propellant (hydrofluorocarbons) containing micronized drug with each actuation. Older devices do not display when the pMDI is empty. However, many new pMDIs have integrated dose counters that display the number of inhalations remaining and alert the user before the pMDIs are empty.1,2 One of the biggest challenges associated with the use of pMDIs is proper inhaler technique. Approximately 51% of users, especially children and the elderly, struggle to efficiently coordinate inhalation with device actuation. The invention of breathe-actuated pMDIs greatly improved inhaler technique by using a flowtriggered system on the conventional pressurized canister that activates once a user inhales. This allows for automatic coordination of inhalation and actuation. Lastly, the use of adjunct spacer devices or valved holding chambers to improve drug delivery and the use of pMDIs.1,2 Dry powder inhalers (DPIs) have a dry powder drug that is propelled into the lungs by the force of the user’s inhalation. The advantages of DPIs include easier use with less coordination and direct delivery into the deep lungs. However, 1 of 3 people still use DPIs incorrectly because of other complications.3 One www.npjournal.org

challenge with the single-dose, breath-activated DPIs is adequate delivery of powder from a punctured capsule inside the device. Delivery is reliant on both the user’s inspiratory flow and the deaggregation of fine drug particles from coarser carrier particles for good dispersion into the lungs. Also, some users incorrectly swallow the capsule instead of inserting it into the device. New multiple-unit DPIs are no longer capsule based and have the capability to deliver

PRESCRIPTION PAD Shalonda D. Williams, PharmD, BCACP extra-fine particles for dispersion. By inducing “particle-particle collision,” they enable the separation of active drug from the carrier.1 Other DPIs allow a simple 3-step operation to encourage adherence: open the cover, inhale from the mouthpiece, and close the cover. Some even include a window that turns “green” to notify the user that it is time to inhale the contents of the device and then turns “red” once administration is completed. Innovative designs also include “active” or power-assisted DPIs. They allow for precise dosing and reproducible aerosol delivery because the success of the device is no longer dependent on the user’s ability to produce a high inspiratory flow rate.1,3 Nebulizers produce a mist of aerosol particles as the result of rapid vibrations of a piezoelectric crystal inside a chamber or the impact between a liquid and a rapid stream of high-velocity gas (air or oxygen). Nebulizers are useful for children, the elderly, and others who have difficulty using proper inhaler technique. Face masks and mouthpieces help deliver medication from the The Journal for Nurse Practitioners - JNP

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machine directly to the mouth of the user. Although nebulizers provide continuous aerosol delivery, much of the drug is lost during exhalation. This results in variable dosing and insufficient delivery of drug to the lungs. Typically, w10% of the dose was deposited in the lungs with the older devices. Newer adaptive aerosol delivery devices coordinate nebulization with inspiration to minimize the amount of aerosol wasted and allow w60% of the dose to reach the lungs. They ensure optimal patient technique and increase compliance.1,2 Soft mist inhalers (SMIs) are the newest inhalation devices. These inhalers are similar to pMDIs in appearance, but there is a spring inside of SMIs that aerosolizes the medicine instead of a propellant. The device forces a metered dose of drug solution through a nozzle, producing two fine streams of liquid that converge to produce a soft mist. SMIs have a higher fine particle fraction (w65%-80%) than both pMDIs and DPIs; therefore, more aerosolized drug is delivered to the lungs.4 Studies show that the slow exit velocity of SMIs improves lung deposition and penetration while allowing less drug to get trapped in the oropharynx. Additionally, a longer generation time encourages adherence by allowing users to have better coordination of inhalation and actuation. Although few SMIs are currently available on the market, these novel inhalers are promising. They facilitate the delivery of consistent and

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reliable doses of drug with each actuation and overcome many obstacles described with other inhalers.3-5 There are many advances in inhalation devices and delivery systems including the design of a new inhaler type, the SMI. Improvements in the devices have led to greater patient adherence and more efficient drug delivery to the lungs. Progress with inhalation devices and delivery systems will continue to change the treatment of respiratory disorders and, ultimately, the management of many other disease states. References 1. Lavorini F, Fontana G, Usmani O. New inhaler devices—the good, the bad, and the ugly. Respiration. 2014;88:3-15. 2. Labiris NR, Dolovich MB. Pulmonary drug delivery. Part II: the role of inhalant delivery devices and drug formulations in therapeutic effectiveness of aerolized medications. J Clin Pharmacol. 2003;56(6): 600-612. 3. Hester SA. PL technician tutorial, dispensing inhaled medications. Pharmacist’s Letter. 2014;30(4):300430. 4. Dalby R, Spallek M, Voshaar T. A review of the development of respimat soft mist inhaler. Int J Pharm. 2004;283(1-2):1-9. 5. Usmani O. Small-airway disease in asthma: pharmacological considerations. Curr Opin Pulm Med. 2015;21:55-67.

Shalonda Williams, PharmD, BCACP, is an assistant professor of pharmacy practice at LIU Pharmacy in Brooklyn, NY, and can be reached at [email protected] Department Editor Timothy Nguyen, PharmD, BCPS, CCP, FASCP, can be reached at [email protected]

1555-4155/15/$ see front matter © 2015 Elsevier, Inc. All rights reserved. http://dx.doi.org/10.1016/j.nurpra.2015.03.008

Volume 11, Issue 6, June 2015