Asthma inhalational drug delivery

Educate patients on the use of inhaled drug delivery devices, peak flow monitors, and asthma education plans. 

An asthma inhaler is an example of a product that contains both a drug and a drug delivery device. Such a product would be regulated primarily as a drug as it achieves its medical purpose by pharmaceutical means. The inhaler would additionally have to satisfy the requirements of a device. 

Evaluate therapy on a regular basis. Assess the patient s control of asthma by evaluating symptoms, PEF diary entries, and rescue medication use. Step long-term control therapy up or down based on these parameters. Before stepping up therapy, reassess the patient s inhaler technique to assure appropriate drug delivery. 

The first commercially available DPI system appeared on the market in 1949, developed and marketed by Abbott under the name Aerohaler. Like all early pulmonary drug-delivery devices, it delivered small-molecule compoimds (bronchodilators or inhaled corticosteroids) to the airways (not necessarily the deep limg) for the treatment of asthma or chronic obstructive pulmonary disease. Table 6 lists some of the early DPI systems used for asthma and COPD the energy somces in these devices were mechanical and patient inspiration. 

Monitoring consists of quantitating the use of inhaled shortacting /S2-agonists, days of limited activity, and number of symptoms (especially nocturnal). The NAEPP recommends yearly spirometric studies. In moderate to severe persistent asthma, once-daily (on awakening) peak-flow monitoring is recommended. Patients also should be asked about exercise tolerance. All patients on inhaled drugs should have their inhalation delivery technique evaluated periodically— monthly initially and then every 3 to 6 months. 

The most important development in antiasthma drug delivery was the advent of the metered-dose inhaler in 1956, which resulted in a huge increase in the use of antiasthma therapy. Sales of pressurized metered-dose inhalers now run at approximately 500 million per year. However, the introduction of this device was not without problems. This section of the chapter covers the early use of propellants in atomization, the origin of the metered-dose inhaler, and the epidemic of asthma deaths. 

Many drugs have been formnlated for use with pressurized metered-dose inhalers (pMDIs) (Table 1). The main market for these devices is in the treatment of asthma, allergic diseases, and chronic obstructive pulmonary disease (COPD), for which approximately 500 million pMDIs are produced each year. Their major selling points are that they are cheap and portable. Despite their huge sales, there is increasing concern that the dose of drug patients with asthma receive will vary considerably due to their inhalational technique and to a lesser extent to the variabihty of dose delivery from the pMDI. It is likely, however, that the popularity of pMDIs will continue due to various modifications and additions that are aimed to help with inhalational technique and improve drug delivery. Examples of these include breath-actuated devices, discussed in this chapter, and spacer devices discussed in a subsequent chapter. 

Inhalation aerosols are known to be very effective for drug delivery through the lungs, notably asthma inhalers, and there is now strong commercial interest in the analysis of inhalable particles. 

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