Inhaleables drug aerosol delivery devices

However, a pMDI without spacer or a DPI with a poor inhalation maneuver is an equally inefficient drug aerosol delivery device. Further, a greater proportion of drag aerosol from pMDIs and DPIs is usually deposited in the mouth, throat, and upper respiratory tract, where the drug is of no therapeutic consequence and may contribute to unwanted local or systemic side effects. 

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. 

Labiris NR, Dolovich MB. Pulmonary drug delivery. Part II the role of inhalant delivery devices and drug formulations in therapeutic effectiveness of aerosolized medications. Br J Clin Pharmacol 2003 56(6) 600-12. 

Wilkes W, Fink J, Dhand R. Selecting an accessory device with a metered-dose inhaler variable influence of accessory devices on fine particle dose, throat deposition, and drug delivery with asynchronous actuation from a metered-dose inhaler. J Aerosol Med 2001 14(3)251-360. 

Pulmonary deposition efficiency depends on physicochemical characteristics, such as density of the aerosol or dry powder particles [33-35], Generally, particle diameters less than than 5 pm are required for efficient pulmonary delivery [36, 37], Pulmonary deposition also depends on the nature of the delivery device and differs between metered dose inhalers (MDIs). For example, pulmonary deposition expressed as the ratio of pulmonary versus total (pulmonary + oral) absorbed drug, ranged from 15-55% for a number of salbutamol devices and from 66-85% for drugs with lower oral bioavailabilities such as budesonide. 

Peart, J. Magyar, C. Byron, P.R. Aerosol electrostatics— metered dose inhalers (MDIs) reformulation and device design issues. In Respiratory Drug Delivery VT, Dalby, R.N., Byron, P.R., Farr, S.J., Eds. Interpharm Press Buffalo Grove, IL, 1998 227-233. 

There are several ways to categorize drug delivery devices. The inhalation drug delivery devices discussed in this article are categorized according to their operating principles or fundamental mechanism of generating aerosols. 

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... 

Inhalers. Various aerosols can deliver liquid drug formulations. The hquid units are inserted into the device which generates the aerosol and delivers it directly to the patient. This avoids any problems associated with converting proteins into powders. This method has applications in delivery of morphine and insulin. 

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