Changes to manufacturing processes of propellant-based metered-dose inhalers (pMDIs) due to the transition to hydrofluoroalkane- (HFA-) based formu lations from chlorofluorocarbon- (CFC-) based systems are under way. These changes are proceeding concurrently with reformulation efforts of the pMDI systems themselves. In some cases, this may result in changes to the formulation [1].

Although the general principles of pMDI manufacture have remained the same during the transition to HFA systems, several processes and technology-related modifications have been required. In general, the manufacturing process is modified according to the final formulation used and the properties of this propellant system.

CFC 11 previously played an important role in the manufacturing process by facilitating the preparation of a concentrate at room temperatures and ambient pressures [2]. There were several technical advantages of manufacturing with nonpressurized systems [3].

The frequent use of ethanol in HFA systems is an example of a required process modification. These systems have required alterations to the elastomers used in the valves and seals of filling equipment due to different extraction and solvent profiles. Also, ethanol is corrosive to unprotected aluminum, and this must be taken into consideration [1]. In terms of manufacturing environment, large quantities of potentially flammable solvents must also be a factor in process design. For pressure filling of HFA propellants, the piston ram system may be replaced by the diaphragm displacement system [1].

Broad reviews of aerosol packaging and production may be found in the literature [4-9]. The following sections focus specifically on the process of placing the components of the aerosol formulation into a sealed container. Thus, it is beyond the scope of this chapter to consider the physicochemical aspects to the development of the formulation itself, the selection of actuators for the value or any other packaging materials (labels, boxes, and package inserts), or subsequent quality control issues.

Coping with Asthma

Coping with Asthma

If you suffer with asthma, you will no doubt be familiar with the uncomfortable sensations as your bronchial tubes begin to narrow and your muscles around them start to tighten. A sticky mucus known as phlegm begins to produce and increase within your bronchial tubes and you begin to wheeze, cough and struggle to breathe.

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