NP Communications, LLC - WebNPOnline

Issues in Pharmacotherapy

Inhalant Agents for Asthma, Bronchospasm, and COPD

March 2010

Inhalant Agents for Asthma, Bronchospasm, and COPD: Focus on Delivery Devices and Inhalation Technique

To achieve optimal drug delivery and therapeutic effect of aerosol inhalant medications, appropriate inhalation technique is essential.^1,2 Evidence-based guidelines for disease management encourage clinicians to educate patients on the role and proper use of inhaled medications while determining which patients would benefit from the use of simple spacers or valved holding chambers (VHCs). Re-educating patients about their tailored and evolving pharmacologic plan of care at every opportunity can not be overemphasized. This concept may also be used to train patients to actively participate in their plan of care.

For example, in the treatment of asthma, bronchospasm, or COPD, patients are educated about the role, utilization, and proper technique for maximum efficacy of their scheduled inhaler and rescue inhaler as individual entities. This task is complicated by the facts that (1) numerous agents in a variety of pharmacologic categories exist; and (2) various and sometimes confusing abbreviations are used for the category of each agent, specific indications for use, the propellants used in delivering the aerosolized agent, and the types of delivery devices. Nurse practitioners must distinguish these agents and abbreviations from one another and effectively communicate this information to patients in a meaningful and useful way—a daunting task further complicated when new products enter the marketplace and changes in formulations occur.

This column presents a basic overview of the inhalant agents used in the treatment of common respiratory conditions, discusses their purpose and proper delivery techniques, and explains associated terminology and abbreviations. If NPs are seeking disease-specific treatment guidelines to assist in the development of individualized treatment plans, they are directed to the websites listed in References 1 and 3.^1,3 Because of patient variability in response to medications, individualization of therapy is required within current evidence-based guidelines for disease management.²

Aerosol Delivery Devices

Aerosol delivery entails a colloidal system in which solid or liquid particles of medication are suspended in a gas and dispensed in a fine spray or mist.⁴ For aerosols to be used therapeutically, they must be generated by devices such as metered-dose inhalers (MDIs), dry powder inhalers (DPIs), or nebulizers. Descriptions of these aerosol devices, as well as optimal techniques for use of each type of device, are discussed in this column. This information is based on the Expert Panel Report 3 (EPR3): Guidelines for the Diagnosis and Management of Asthma from the National Institutes of Health.¹ Using this background information, NPs are encouraged to assess patients’ inhalation techniques on a routine basis.

Of note, MDI propellants have changed from chlorofluorocarbon (CFC) to hydrofluoroalkane (HFA).5 NPs can learn more about this change in propellants by logging on to http://www.getasthmahelp.org/inhalers_main.asp.⁵ Readers are also directed to an article entitled Switching from CFC to HFA Inhalers: What NPs and Their Patients Need to Know, by Velsor-Friedrich et al, which was published in The American Journal for Nurse Practitioners this past October (Am J Nurse Pract. 2009;13[10]:45-50).

Metered-dose Inhaler—An MDI consists of a pressurized canister containing active drug(s), propellants, and co-solvents and/or surfactants.⁶ Active drug is either dissolved in solution or it is a suspended micronized powder.⁶ Accurate delivery of a suspension requires that the canister be shaken before medication is administered.⁶ The canister is equipped with a metering chamber and valve for measurement and release of the aerosolized medication.⁶ MDIs are portable, convenient, and recommended for patients ≥5 years old; in younger patients, the MDI is used with a spacer or VHC face mask.

Optimal technique: Optimal actuation requires a slow (30 L/min or 3-5 seconds), deep inhalation, followed by a 10-second breathhold.¹ An open mouth technique (MDI held 2 inches away from the mouth) has not been shown to enhance clinical benefit relative to the closed-mouth technique (ie, inserting the MDI mouthpiece between the lips and the teeth).¹ Reference 5 provides an illustrated description of administration technique.⁵

Breath-actuated MDI—A breath-actuated MDI (eg, Autohaler) is lever-cocked to load the dose of medication.⁶ Then patients inhale; the inspiratory pressure causes a baffle (screen) to open, allowing the dose to be expelled from the canister metering chamber.⁶ This device is portable, convenient, and recommended for patients ≥5 years old. It may also be useful for patients, particularly seniors, who are unable to coordinate inhalation and actuation.

Optimal technique: Patients make a tight seal around the mouthpiece and inhale slightly more rapidly than with the standard MDI (as noted above), followed by a 10-second breathhold.¹ Patients are instructed not to stop inhaling at actuation.¹ This type of device is not compatible with spacer/VHC devices.^1,2

Dry Powder Inhaler—A DPI enables dry micronized powder to be inhaled directly into the lungs.² The advantage of DPIs is the feature of breath-actuation, which requires minimal hand–lung coordination.⁷ However, use of this device depends on minimally effective inspiratory flow.¹ Varying characteristics exist among DPIs, some of which are more flow-dependent than others.⁷ DPIs are portable, convenient, and recommended for patients ≥4 years old. Younger c