According to the most recent study of asthma prevalence conducted by the Centers for Disease Control and Prevention, in 2001, 31.3 million people (114 people per 1,000 - U.S.) had ever been diagnosed with asthma during their lifetime. Beginning with the 2001 National Health Interview Survey (NHIS), current asthma prevalence includes people who have been diagnosed with asthma by a health professional and who still have asthma. In 2001, 73 people per 1,000 or 20.3 million people, had asthma at the time of the interview. Rates decreased with age; 87 per 1,000 children 0-17 years (6.3 million children) had asthma compared to 69 per 1,000 adults 18 years and over (14 million adults).
When race/ethnicity is considered, current asthma prevalence was about 10% higher among non-Hispanic blacks compared to non-Hispanic whites and about 40% higher compared to Hispanics. Females had a 30% higher prevalence compared to males. However, this pattern was reversed among children. The current asthma prevalence rate for boys aged 0-17 years (99 per 1,000) was over 30% higher than the rate among girls (74 per 1,000).
Asthma is a disease that causes the airway tubes that carry air-in the lungs to overreact and become "twitchy" so they become temporarily constricted or blocked in response to an asthma trigger. When this occurs, the person with asthma may feel as though he or she cannot get enough air or simply can't breathe effectively. Put in more technical terms, asthma is characterized by airway inflammation, increased airway responsiveness ("twitchiness"), and variable airflow obstruction. Most researchers agree that the tendency to have asthma is inherited and that the airways tendency to overreact is often present from infancy.
One of the defining characteristics of asthma is that the airway obstruction is reversible (though not always completely reversible) and may resolve on its own or with treatment. Since the airway obstruction is variable, asthma may be described as "episodic" in that most people who have it breathe normally or near normally between episodes or acute attacks. In addition to being episodic, asthma is also considered to be chronic (an ongoing problem) and people with asthma have airways that remain inflamed and may get constricted after exposure to an asthma trigger.
During an asthma attack, the bronchioles and alveoli (conducting airways of the lungs) become narrowed or blocked. The muscles that encircle these bronchioles and alveoli that conduct air within the lungs constrict (tighten). When the airways narrow, fluid, blood cells, and irritating chemicals produced by the body enter the bronchioles and cause the linings of the airways to become inflamed. This inflammation further narrows the air passages. The inflammation signals mucous glands in the bronchioles to secrete more mucus than usual, which causes the airways to become plugged or blocked.
Types of Asthma
Although asthma is characterized by specific changes in the lungs that result in respiratory difficulty for asthma sufferers, it has also been categorized in a variety of ways. It should be noted that some of the conditions listed below have similar components to those of Chronic Obstructive Pulmonary Disease (COPD) and Interstitial Lung Disease (ILD). This means that some have an inflammatory component.
- Extrinsic asthma is asthma that is brought on by external agents such as pollens or chemicals. It is commonly diagnosed early in life, and is usually caused by the body's responses to inhaled allergens. Intrinsic asthma is asthma due to within-the-body (endogenous) factors such as adrenalin release due to stress or to exertion. It generally develops later in life, and very little is known about what causes it. Intrinsic asthma tends to be less responsive to treatment than extrinsic asthma. Triggering factors include infection, exercise, and drugs such as aspirin.
- Exercise-induced asthma is defined as asthma attacks that follow a period of exercise. Such attacks are usually short-lived and resolve without treatment. People with exercise-induced asthma may also have other underlying precipitating factors.
- Acute severe asthma, previously known as status asthmaticus, is a sudden, intense, and continuous aggravation of asthma that does not respond to the usual therapeutic measures. It is characterized by breathing difficulty that leads to exhaustion and collapse. People with acute severe asthma can deteriorate very rapidly and can die within the first 24 hours of onset.
- Occupational asthma, which usually occurs in response to irritants and allergens in the workplace. Those with occupational asthma may not experience symptoms when not at work.
- Weather-related asthma occurs in response to changes in weather.
- Asthma may be triggered by gastro esophageal reflux disease (GERD).
- Acute or chronic sinusitis and allergic rhinitis may aggravate asthma.
- Sleep or nocturnal asthma is asthmatic symptoms that become more evident at night. These symptoms are probably not related to lying down or to sleep and instead probably reflect the ongoing inflammatory state of the airways. Hormone-related asthma may occur in some women who experience aggravation of asthma shortly before their menstrual periods.
- Use of oral contraceptives may also aggravate asthma. An overactive thyroid gland has been linked to provoking or worsening asthma; treatment of the overactive thyroid may help relieve asthma symptoms.
The FDA has determined that N115 has sufficient safety toxicology and clinical data to proceed with the multi-dose, extended use, clinical trials. Phase III/Phase IV studies will focus on asthmatics and COPD patients. On the basis of existing clinical data, EmphyCorp is confident that its Investigative New Drug, N115, can and will be used for maintenance or continuous treatment of patients over extended periods of time. The Company believes that N115 will set the standard in the pharmaceutical industry for the treatment of major pulmonary diseases.