Steroids such as corticosteroids are naturally occurring chemical substances (hormones) produced by the healthy human body. The individual compounds that make up the steroid family have important roles in regulating many of the critical processes involved in our well-being.
Hormones are chemical messengers produced in one organ and released into the bloodstream to exert their effects on another organ. Insulin is an example of a hormone; produced in the islet cells of the pancreas gland, it travels to the blood circulation and helps regulate glucose (sugar) uptake from food into organs such as the liver, fat tissue, and muscle. Some of the hormones our bodies make are members of the steroid family of chemical compounds.
The organs that produce steroid hormones are the adrenal glands, the ovaries, and the testes. During pregnancy, the placenta, an additional steroid-producing organ, develops, which produces the hormones required for the successful continuation of the pregnancy. The sex hormones estrogen and testosterone are synthesized by the ovary and testis, circulate in the bloodstream, and affect many different organs throughout the body. Similarly, the body’s two adrenal glands produce adrenocortical steroids (hydrocortisone, cortisone, aldosterone, and progesterone).
Scientists have succeeded in creating (or synthesizing) steroids, including corticosteroids, in the laboratory for medical use. Corticosteroids have widespread useful-ness in a diverse group of medical conditions. These steroid medicines are manufactured in different formulations to treat a variety of specific conditions. You may be surprised to learn that corticosteroid medicines are manufactured as eye drops, nasal sprays, inhalers, creams and ointments, syrups, and pills, in an intravenous form, and even as a rectal suppository.
Corticosteroids are invaluable to physicians who care for persons with inflammatory eye diseases such as uveitis, skin ailments such as psoriasis and eczema, rheumatologic diseases such as rheumatoid arthritis and lupus, inflammatory bowel diseases, some kidney diseases, and, of course, several lung diseases, especially asthma.
Corticosteroid medications are important because they have powerful anti-inflammatory effects; they reduce inflammation, which is the main problem in asthma and severe allergies. Corticosteroids in inhaled forms are the most effective asthma controller medicines available and are recommended asthma treatment for persons of all ages, including children. Inhaled corticosteroids are thus extensively used in asthma management and are the cornerstone of preventive therapy for all forms of persistent asthma.
Inhaled Corticosteroids (ICS) in Asthma: Key Points
ICS are manufactured as inhalers (MDI, DPI) and in solution for nebulization.
ICS are daily-use maintenance controller medicines.
ICS are the cornerstone of preventive therapy for all forms of persistent asthma.
ICS use prevents symptoms of asthma from developing.
ICS use reduces or suppresses airway inflammation.
ICS use improves asthma-specific quality of life.
ICS use increases lung function.
ICS use leads to fewer lung symptoms, fewer exacerbations, and fewer severe attacks that result in hospital admission or death.
The two major physiologic reactions that characterize poorly controlled or uncontrolled asthma are bronchoconstriction and ongoing inflammation. The muscles that surround the bronchi (air passageways) go into spasm (bronchospasm), which causes the airway to narrow (bronchoconstriction). As an exacerbation progresses, several types of white blood cells including eosinophils, lymphocytes, mast cells, and neutrophils become stim-ulated and in turn release various chemicals called mediators. The white cell mediators cause an inflammatory reaction within the walls of the bronchial passageways.
Ongoing, uncontrolled inflammation not only contributes to persistent bronchospasm, but also represents the greatest potential for causing chronic lung changes and reduced lung function in asthma. We now understand that this process can be a silent phenomenon, like high blood pressure or elevated cholesterol. A heightened inflammatory response is present to some degree in every person with asthma, even in those with mild disease.
Asthma is now considered a chronic inflammatory disorder of the lungs. The response of the lungs to persistent inflammation may result in changes that never go away. The term currently used to describe this phenomenon is airway remodeling. Airway remodeling may contribute to declines in lung function in some persons with asthma.
Lung function abnormalities seen in asthma were traditionally considered a wholly reversible phenomenon. Within the past 2 decades, our ideas about this concept have slowly evolved. There seems to be a subgroup of patients with asthma who appear to have greater degrees of inflammation in their lungs. Within that group, certain individuals’ lung function never does return entirely to normal. It is unclear why exactly airway remodeling occurs.
One hypothesis suggests that it results from unappreciated long-term effects of chronic asthmatic bronchial inflammation. However, the multiple factors responsible for the pathologic process called remodeling are still not completely understood. An article in the March 5, 2009, issue of The New England Journal of Medicine reviewed available drug therapies in asthma and noted the beneficial clinical outcomes of persons with asthma treated with inhaled corticosteroids (ICS).
The authors point out that although there is no scientific evidence that ICS prevented the lung function decline observed in some persons with asthma, regular ICS use reduced or suppressed airway inflammation in asthma, increased lung function, improved asthma-specific quality of life, led to fewer asthma symptoms, fewer exacerbations, and fewer severe attacks leading to hospitalization or death.
Despite overwhelming and convincing evidence of the benefits of inhaled ICS in all forms of persistent asthma, physicians are not following national guidelines (such as the NAEPP’s Expert Panel Report) for ICS pre-scribing in asthma!