Inhalation Drug Delivery System Designmetereddose Inhalers Introduction

A metered-dose inhaler (MDI) is a complex system designed to provide a fine mist of medicament, generally with an aerodynamic particle size of less than 5 microns, for inhalation directly to the airways for the treatment of respiratory diseases such as asthma and COPD.

The main components of all MDIs (Fig. 4) are:

• The active ingredient

• The propellant (a liquefied gas)

• A metering valve

• An actuator/mouthpiece

The active ingredient (the drug) may be either dissolved in the propellant or a cosolvent (e.g., ethanol) or suspended in the propellant. A surface-active agent

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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