Inhalation devices, portable

The transportable model has a flow from the sniffing port of 190 1/minute and the portable of 60 1/minute. The inhalation device should be loose enough to hold overpressure during expiration below 5 millibars (France). 

Several portable inhalation devices have been developed and are being tested to determine whether they improve protein and peptide delivery via the airways. Aerosolized DNase has been shown in patients with cystic flbrosis to significantly reduce the buildup of mucus in the lung and the incidence of infections. Devices for delivery of therapeutic proteins to deep-lung alveoli to achieve systemic effects are also in development. These products are formulated so that the device aerosolizes the protein in a defined particle size range that cannot be easily achieved by means of conventional metered dose inhalers. 

Nebulizer jet nebulization ultrasonic nebulization. Generates small particles with higher delivery capacities than pMDIs and DPIs no coordination required. Inconvenient long inhalation times poor dose control lack of portability expensive. More compact and portable devices breath enhanced nebulizers dosimetric nebulizers. 

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. 

The modern pressurized metered dose inhaler (pMDI) was developed between 1955 and 1956. However, the pMDI had its roots in research carried out many years before.During the 1930s and 1940s, the discovery of liquefied propellants (chlorinated-fluorocarbons or freon propellants) such as CFC12, CFC114, CFCll, and CFC22 was a major step in the realization of a portable inhaler. However, the first pMDI was not invented until 1956, when the metering valve used in the device was developed and patented. ... 

The metered solution inhaler (MSI), under development by Sheffield Pharmaceuticals, uses the same aerosolization principle as the AeroDose. The MSI is a portable, hand-held drug delivery device, as shown in Fig. 13. Using a motorized pump, drug solution is delivered to the surface of a ultrasonic horn powered... 

Another very elegant and highly portable device that aids patient coordination is the breath-actuated inhaler, originally developed by Riker Laboratories (3M) [47] and further enhanced by Ivax-Norton (EasiBreathe). In this type of device, a mechanical release mechanism is used, firing the MDI when a certain threshold inspiratory flowrate is reached. Once the dose has been dispensed, the device is then reprimed, ready for use. This type of device has gained wide acceptance in Europe and has been introduced for several MDI products. 

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. 

If a dust hazard is suspected in the workplace, the first step is to monitor the working environment to determine the exposure of the worker. One of the better methods of achieving this is for the worker to wear a portable sampling device, which gives a measure of the type of particles and their size distribution in the air immediately around the worker. Such devices usually sample at a typical respiration rate and velocity and some devices are designed to capture directly only the respirable particles (particles capable of reaching the alveoli) or the inhalable particles (particles capable of being inhaled). 

---