Respiratory tract/system disease

In the context of allergies, sensitization is the process by which a person becomes, over time, increasingly allergic to a substance (sensitizer) through repeated exposure to that substance. Allergies are inappropriate or exaggerated reactions of the immune system to substances that, in the majority of people, cause no symptoms. Symptoms of the allergic diseases may be caused by exposure of the skin, the respiratory tract, or of the stomach and intestines to a protein or a chemical substance. 

IL-5 is usually not present in high levels in humans. However, in a number of disease states where the number of eosinophils is elevated, high levels of IL-5 and its mRNA can be found in the circulation, tissue and bone marrow. These conditions include the diseases of the respiratory tract, hematopoietic system, gut and skin. Some other examples include food and drug allergies, atopic dermatitis, aspirin sensitivity and allergic or nonallergic respiratory diseases. 

Most of the information on the effects of air pollution on humans comes from acute pollution episodes such as the ones in Donora and London. Illnesses may result from chemical irritation of the respiratory tract, with certain sensitive subpopulations being more affected (1) very young children, whose respiratory and circulatory systems are poorly developed, (2) the elderly, whose cardiorespiratory systems function poorly, and (3) people with cardiorespiratory diseases such as asthma, emphysema, and heart disease. Heavy smokers are also affected more adversely by air pollutants. In most cases the health problems are attributed to the combined action of particulates and sulfur dioxides (SO2) no one pollutant appears to be responsible. Table 4.2 summarizes some of the major air pollutants and their sources and effects. 

Inhalation Inhalation provides the rapid delivery of a drug across the large surface area of the mucous membranes of the respiratory tract and pulmonary epithelium, producing an effect almost as rapidly as by intravenous injection. This route of administration is used for drugs that are gases (for example, some anesthetics), or those that can be dispersed in an aerosol. The route is particularly effective and convenient for patients with respiratory complaints (for example, asthma or chronic obstructive pulmonary disease) as drug is delivered directly to the site of action and systemic side effects are minimized (see p. 219). 

Second, inhaleables enable effective drug targeting to the lungs for relatively common respiratory tract diseases such as asthma, emphysema, bronchiectasis and chronic bronchitis. This direct delivery most often results in a better treatment outcome while potentially requiring less drug than if given systemically either orally or by injection. 

Numerous proteins have been investigated for administration to the respiratory tract to treat local disease. In some of these investigations, absorption into the systemic circulation was also followed. These results have their utility when absorption of similar molecules is being considered for the purpose of systemic delivery or to estimate the systemic exposure of locally delivered macromolecules for safety purposes. 

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