Aerosolized medications are unique because of the complexity of their formulation requirements and the necessary engineering for their delivery devices. Medications loaded into MDIs or dry powder inhalers (DPIs) must be prepared so that they will disperse quickly and not reaggregate in the generation process, and the device must be easy to use and deliver accurate dose. There is no accurate control of the quantity reaching the target area. Intravenous medications are simpler—a known dose can be delivered and pharmacokinetic and pharmacodynamic properties examined. Ingested medications can be defined in terms of fraction absorbed from the gut and pharmacokinetic and pharmacody-namic performance. Inhaled particles must be created with less than full understanding of the factors that control dose: (1) physical properties of the particle, (2) the generation system, and (3) patient inhalation techniques. All of these lead to a much more "nebulous" design process than commonly encountered with intravenous or oral medications.
Because of the uncertainty in dose delivery and the relatively benign nature of many inhaled medications used in past years, large quantities were often delivered from nebulizers to assure results. The term dose overkill will occasionally be used, meaning the administration of such a large dose that, no matter how inefficient the delivery system, enough will get to the right place to cause maximum effect, as might be expected with receptor saturation when using beta adrenergic bronchodilators.
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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.