Pressurized metered dose inhaler actuator

The Easyhaler (by Orion Pharma, Finland) and the Clickhaler (by Innovata pic, United Kingdom) are available at present in some European markets. Unlike the DPIs described earlier, these two reservoir-type inhalers meter the dose when the patient presses the top of the device similar to actuation of a pressurized metered-dose inhaler. Both devices contain a dose indicator, which is standard for reservoir multidose DPIs. Recently, Innovata presented the Twinhaler for asthma combination therapy, a new development based on the Clickhaler. This device does not require the combined drugs to be formulated in one powder blend but delivers two powder formulations from two reservoirs into one airflow path. 

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. 

Key pMDI, pressurized metered-dose inhaler VC, vital capacity BHT, breath holding tune BA, breath-actuated measured by scintigraphy. 

The pressurized metered dose inhaler (pMDI) is a pocket sized, hand-held drug delivery system designed to deliver consistent small doses of medicines directly to the patient s lungs. The essential constituents are the medicine, the propellant, and a storage canister, a metering valve, and an actuator. This chapter is concerned with the propellants. It addresses... 

Metered-dose inhalation aerosols Delivered dose per actuation, number of metered doses, color, particle-size distribution, loss of propellant, pressure, valve corrosion, spray pattern, and absence of pathogenic microorganisms... 

Aerosolized medications are available as pressurized or breath-actuated metered-dose inhalers (MDIs), dry powder inhalers (DPIs), and nebulized or wet aerosols. Most inhaled medications currently used are available as metered-dose inhalers (Table 3). For the patient who has difficulty to coordinate activation of a MDI, a spacer improves delivery. Spacers reduce deposition of the drug in the... 

The active component of inhalation aerosol is beclomethasone dipropionate, an anti-inflammatory corticosteroid having the chemical name 9-chloro-ll(beta),17,21-trihy-droxy-16(beta)-methylpregna-l,4-diene-3,20-dione 17,21-dipropionate. It is a pressurized, metered-dose aerosol intended for oral inhalation only. Each unit contains a solution of beclomethasone dipropionate in propellant HFA-134a (1,1,1,2 tetrafluoroethane) and ethanol. The 40-mcg strength delivers 40 meg of beclomethasone dipropionate from the actuator and 50 meg from the valve. The... 

Figure 4 Schematic production sequence for the manufacture of metered-dose inhalers by pressure filling (1) suspension mixing vessel (2) can cleaner (3) can crimper and filler (4) check weigher (5) can coder and heat tester (6) priming and spray testing (7) labeler (8) feeds for tested cans and actuators. (Courtesy of Ellis Horwood Publishers, Ref. 10.)...

Metered dose inhaler has been the most popular aerosol delivery device for the treatment of respiratory diseases, which is attributable to its portability and simple operation. Although seemingly easy to use, the MDI is a sophisticated device in design. The drug(s) are suspended or dissolved in a liquefied propellant system, which may also contain excipients such as cosolvents or surfactants. The formulation is kept pressurized in a small canister, sealed with a metering valve. Upon actuation through an actuator, the valve opens and the metered dose is dispensed as an aerosol spray from the expansion and vaporization of the propellant under ambient pressure. The inhalers may be used alone or with spacer devices, the electrostatic issues of which are considered in a later section. The present discussion focuses on the inherent charging of particles produced from MDIs. 

Metered dose inhalers (MDIs) are pharmaceutical delivery systems designed for oral or nasal use, which deliver discrete doses of aerosolized medicament to the respiratory tract. The MDI contains the active substance, dissolved or suspended in a liquefied propellant system held in a pressurized container that is sealed with a metering valve. Actuation of the valve discharges a metered dose of medicament as an aerosol spray through an actuator during oral or nasal inhalation. 

Figure 10 Photograph of a breath-actuated metered-dose pressurized-pack inhaler (Autohaler).

The compound is available in inhalation aerosol, injectable, and tablet dosage forms. The inhalation aerosol is the most unique of the three dosage forms. The aerosol consists of a suspension of fine terbutaline sulfate in a pressurized aerosol container equipped with a metered dose valve and oral inhalation actuators. 

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