Anaphylaxis Treatment and Antihistamines Quiz

Allergies, Antihistamines, and Antiallergics

• Allergies occur when the immune system reacts to a harmless substance, an allergen.
• Allergens include pollen, dust mites, animal dander, foods, and insect stings.
• Antihistamines block the effects of histamine, a chemical released during allergic reactions.
• Histamine causes itching, swelling, and redness by dilating blood vessels.
• Antihistamines work by preventing histamine from binding to its receptors (H1 receptors).
• H2 receptors are in the stomach and are also important targets for some antihistamines (H2 receptor blockers).
• H1 receptors also exist in the bronchioles, and some antihistamines are good targets to help treat allergic bronchoconstriction.
• Urticaria (hives) is a skin condition characterized by raised, itchy welts.
• Anaphylaxis is a severe allergic reaction that needs immediate medical attention.
• Antihistamines have varying degrees of sedative effects, especially first-generation antihistamines.
• Antihistamines can interact with other medications, such as hypnotics, sedatives, anxiolytics, or alcohol, potentially intensifying sedative effects.
• Antihistamines are used in various conditions like allergic reactions, dry nasal secretions, nausea, common cold symptoms, and as sleep aids.
• Cromolyn sodium is an antiallergic medication that inhibits the release of histamine.
• Cromolyn is a preventive treatment and should be used before symptoms arise.
• Antiallergic medications often target mast cells, a type of immune cell responsible for releasing histamine.

Types of Antihistamines

• Antihistamines are classified into first-generation and second-generation based on their actions and side effects.
• First-generation antihistamines often cause drowsiness due to their ability to cross the blood-brain barrier.
• Second-generation antihistamines usually have less drowsiness and fewer sedative side effects, primarily block H1 receptors peripherally.
• First-generation antihistamines include diphenhydramine (Benadryl), chlorpheniramine, doxylamine (Unisom), promethazine (Phenergan).
• Second-generation antihistamines include loratadine (Claritin), cetirizine (Zyrtec), fexofenadine (Allegra).
• Some specific antihistamines are available as over-the-counter products (OTC). Others might be RX only.
• Some 1st-gen antihistamines can be used for sleep aids (OTC).

Other Allergy-Related Terms

• Allergen: A substance causing an allergic reaction, often a protein.
• Antigen: A substance that triggers an immune response (often a foreign protein).
• Antibody: Proteins produced by the immune system in response to an antigen, binding to and neutralizing antigens.
• Rhinitis: Inflammation of the nasal lining, often caused by allergens.
• Erythema: Reddening of the skin due to increased blood flow (often related to hypersensitivity/inflammation).
• Dermatitis: Inflammation of the skin (often associated with an allergic reaction or irritation).

Important Actions of Histamine

• Vasodilation of capillaries (leads to redness and inflammation)
• Contraction of smooth muscles.
• Increased heart rate.

Different Clinical Situations and Considerations

• Different antihistamine use for different medical scenarios and conditions.
• How to correctly use the Cromolyn inhaler
• Understanding antihistamine properties in relation to various medical scenarios and factors.
• Understand that antihistamines act upon the nervous system through various receptor sites.
• Recognize the different side effects, especially drowsiness, with use of some antihistamines.

Drug Interactions

• Antihistamines can interact with other drugs, potentially increasing drowsiness or other side effects.

Adverse Effects and Contraindications of Antihistamines

• First-generation antihistamines can have more side effects that can include drowsiness, dry mouth, hypotension (low blood pressure), rapid heartbeat, anorexia, and urinary retention.
• First generation (1st) antihistamines can have more adverse effects overall and should be carefully considered given their greater potential for sedation.
• Second-generation antihistamines have a lower potential for side effects.

Other Information

• Some antihistamines are also used for conditions other than allergies and can have diverse pharmacological activities relevant in various clinical settings.
• The role of H1 and H2 receptors is crucial in understanding their different actions.
• The study suggests the correct administration of Gastrocrom medication.
• There are important considerations for the safety and effective use of antihistamines during pregnancy .