Inhaled Corticosteroids: Uses & Indications

• Adrenal cortical hormones are steroids secreted by the adrenal cortex.
• Endogenous refers to substances produced inside the body.
• Exogenous refers to substances manufactured to be placed inside the body, such as medication.
• Immunoglobulin E (IgE) is a gamma globulin produced by cells in the respiratory tract.
• Prostaglandins are hormone-type substances circulating throughout the body.
• Steroid diabetes is hyperglycemia resulting from glucocorticoid therapy.
• Steroids, also known as glucocorticoids or corticosteroids, produce an antiinflammatory response.

Clinical Indications for Inhaled Corticosteroids

• Inhaled corticosteroids are available for oral inhalation (lung delivery) and intranasal delivery.
• Orally inhaled agents are for maintenance and control therapy of chronic persistent asthma, identified as requiring step 2 care or greater.
• Step 2 asthma involves symptoms occurring more than 2 days/week but not daily; night awakenings occur 3 to 4 nights/month, with FEV1 or PEF 80% of predicted or greater.
• Inhaled agents can be used with systemic corticosteroids in severe asthma and may allow for reduction or elimination of systemic corticosteroids for asthma control.
• Inhaled corticosteroids in combination with other agents are recommended by the American Thoracic Society (ATS).

Identification of Aerosolized Corticosteroids

• Beclomethasone dipropionate HFA (QVAR)
• Flunisolide hemihydrate HFA (AeroSpan)
• Fluticasone propionate (Flovent HFA, Flovent Diskus)
• Fluticasone furoate (Arnuity Ellipta)

Identification of Aerosolized Corticosteroids (Combinations)

• These contain two medications
• Fluticasone Propionate/Salmeterol (Advair Diskus, Advair HFA)
• Budesonide/Formoterol Fumarate HFA (Symbicort)
• Mometasone Furoate/Formoterol Fumarate HFA (Dulera)
• Fluticasone Furoate/Vilanterol (Breo Ellipta)

Hypothalamic–Pituitary–Adrenal Axis (HPA Axis)

• This is the pathway for release and control of endogenous corticosteroids.
• Stimulation of the hypothalamus causes impulses to be sent to the median eminence, where corticotropin-releasing factor (CRF) is released.
• CRF goes to the anterior pituitary gland where corticotropin is released into the bloodstream.
• Corticotropin, or adrenocorticotropic hormone (ACTH), stimulates the adrenal cortex to secrete glucocorticoids, such as cortisol.

HPA Suppression with Steroid Use

• The body cannot distinguish between endogenous and exogenous steroids.
• Administration of glucocorticoid drugs raises the body’s level
• This inhibits the hypothalamus and pituitary glands.
• This is referred to as HPA suppression or adrenal suppression.

Physiology of Aerosolized Corticosteroids

• The production of the body’s own glucocorticoids follows a rhythmic cycle, termed diurnal or circadian rhythm.
• Cortisol levels are highest in the morning at 8 a.m.
• Examples of interference with the cycle include jet lag and night shift work.

Alternate-Day Steroid Therapy

• Mimics natural diurnal rhythm by giving a steroid drug early in the morning when normal tissue levels are high.
• On alternate days, regular diurnal secretion in the HPA system can resume.

Corticosteroids

• These are a class of medications used to treat inflammation.
• They are used with asthmatics and COPD patients to achieve an anti-inflammatory effect.

Nature of Inflammatory Response

• Inflammation produces redness, swelling, heat, and pain.
• Triple response:
  • Redness: Local dilation of blood vessels, occurring in seconds
  • Flare: Reddish color several centimeters from the site, occurring 15 to 30 seconds after injury
  • Wheal: Local swelling, occurring in minutes

Nature of Inflammatory Response: Four Categories

• Increased vascular permeability: An exudate is formed in surrounding tissues. Leukocytic infiltration: White blood cells (WBC) emigrate through capillary walls (diapedesis) in response to attractant chemicals (chemotaxis).
• Phagocytosis: White cells and macrophages (in lungs) ingest and process foreign material such as bacteria. Mediator cascade: Histamine and chemoattractant factors are released at the injury site; various inflammatory mediators, such as complement and arachidonic acid products, are generated.

Nature of Inflammatory Response (Airway)

• Chronic bronchitis (usually caused by tobacco smoking) and asthma (range of triggers) are most common.
• Treatment with antiinflammatory agents such as glucocorticoids is important to reduce the basal level of airway inflammation, thereby reducing airway hyperresponsiveness and predisposition to acute episodes of obstruction.
• Asthmatic reactions are biphasic, namely early phase and late phase.
• Early asthmatic response is caused by immunoglobulin E (IgE).
  • This response peaks at ~15 minutes.
• Mast cells and eosinophils are the major cells responsible for an inflammatory response in asthma.
• Mast cell mediators and the release of cytokines recruit other inflammatory cells to cause a late-phase reaction.
  • This response occurs after ~6–8 hours and can last up to 24 hours.

Explore the clinical uses of inhaled corticosteroids for asthma management. Learn about their role in maintenance and control therapy for chronic persistent asthma. Understand the difference between endogenous and exogenous substances and their relevance to steroid treatments.