Drugs for Inflammation, Fever, and Allergies Expanded Key ...



|Drugs for Inflammation, Fever, and Allergies |

|Expanded Key Concepts |

31.1 Inflammation is a natural, non- specific response that limits the spread of invading microorganisms or injury. Acute inflammation occurs over several days whereas chronic inflammation may continue for months or years.

Inflammation is a non-specific response designed to rid the body of invading organisms that may occur in response to a large number of different stimuli. This includes physical injury, exposure to toxic chemicals, extreme heat, invading microorganisms or death of cells. Acute inflammation occurs quickly and may require aggressive pharmacotherapy.

31.2 Histamine is a key chemical mediator in inflammation. Release of histamine produces vasodilation that allows capillaries to become leaky, thus causing tissue swelling.

Chemical mediators initiate inflammation. One of the most important mediators is histamine. Histamine dilates nearby blood vessels, causing capillaries to become more permeable. It allows complement proteins and phagocytes to enter the area to neutralize foreign agents. Extremely rapid release of histamine throughout the body can cause anaphylaxis.

31.3 Histamine can produce its effects by interacting with two different receptors.

The classic antihistamines used for allergies block H1 histamine receptors in vascular smooth muscle, in the bronchi, and on sensory nerves. The H2 receptor antagonists are used to treat peptic ulcers.

H1 receptor antagonists are used to treat allergies and inflammation whereas H2 receptor antagonists are used to treat peptic ulcers.

31.4 Nonsteroidal anti-inflammatory drugs (NSAIDS) are the primary drugs for the treatment of simple inflammation. Newer, selective COX-2 inhibitors cause less GI distress.

NSAIDs are drugs that inhibit the enzyme, cyclooxygenase. Nonselective cyclooxygenase inhibitors, including aspirin, are very effective at reducing inflammation and pain, but cause significant GI side effects in some patients. The newer, selective COX-2 inhibitors cause less GI disturbance.

31.5 Systemic glucocorticoids are effective in treating acute or severe inflammation. As over- treatment with systemic glucocorticoids can cause a serious condition called Cushing's syndrome, therapy for inflammation is generally short-term.

Glucocorticoids have the ability to suppress histamine release and inhibit the synthesis of prostaglandins by cyclooxygenase-2. In addition, they can inhibit the immune system by suppressing certain functions of phagocytes and lymphocytes. Glucocorticoids are the most efficacious medications available for the treatment of severe inflammatory disorders.

31.6 NSAIDs and acetaminophen are the primary agents used to treat fever.

Prolonged, high fever is an indication for drug therapy. Aspirin and other NSAIDs are the drugs of choice for adults. Acetaminophen is the drug of choice for children.

31.7 Allergic rhinitis is a disorder characterized by sneezing, watery eyes, and nasal congestion.

Allergic rhinitis, also known as hay fever, is a chronic allergy triggered by a wide variety of antigens. The release of chemicals mediating the immune response can result in seasonal symptoms for some patients and chronic, continuous symptoms for others.

31.8 Antihistamines, or H1 receptor antagonists, can provide relief from the symptoms of allergic rhinitis. Newer drugs in this class are non- sedating and offer the advantage of once-a-day dosage.

The H1 receptor antagonists, commonly known as antihistamines, are used to treat allergies and inflammation. Antihistamines are most effective when taken prophylactically to prevent allergic symptoms. They are also among the few drugs available to treat vertigo, a form of dizziness that causes significant nausea.

31.9 Intranasal glucocorticoids have become the drugs of choice for treating allergic rhinitis due to their high efficacy and wide margin of safety.

Glucocorticoids may be applied directly to the nasal mucosa to prevent symptoms of allergic rhinitis. They have begun to replace antihistamines as the drugs of choice for the treatment of chronic allergic rhinitis. When used by inhalation, intranasal glucocorticoids do not produce the serious adverse effects that have been observed when they are given orally.

31.10 Oral and intranasal sympathomimetics are used to alleviate nasal congestion due to allergic rhinitis and the common cold. Intranasal medications are more efficacious, but can only be used for 3 to 5 days due to rebound congestion.

Sympathomimetics with alpha adrenergic activity are effective at relieving nasal congestion associated with allergic rhinitis when given by either oral or intranasal routes. Though effective with a rapid onset of action, use of the intranasal preparations is usually limited to 3-5 days due to the potential for rebound congestion.

31.11 Anaphylaxis is a serious and often fatal allergic response that is treated with a large number of different drugs. These include: sympathomimetics, antihistamines, and glucocorticoids.

When the body mounts a hyper-response to an antigen, anaphylactic shock may result. Epinephrine is a drug of choice for immediately reversing the cardiovascular symptoms. Other vasoconstrictors, antihistamines, and corticosteroids also serve a role in treating this form of shock.

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