NSG 116 Chapter 32 Flashcards: Drug Therapy for Histamine Effects and Allergic Response

Practice flashcards for reviewing key vocabulary related to drug therapy to decrease histamine effects and allergic response, based on lecture notes for NSG 116 Chapter 32.

Histamines

The first chemical mediator released in immune and inflammatory responses, stored in most body tissues.

Histamine Location

Found in body tissues, CNS, and concentrated in environmentally exposed areas like eyes, nose, lungs, and GI tract.

Histamine Release Stimuli

Allergic reactions, cellular injury, and extreme cold can cause histamine discharge.

Bronchoconstriction (Histamine Effect)

Narrowing of respiratory airways, a common effect of histamine release.

Cough and/or respiratory distress (Histamine Effect)

Symptoms indicating difficulty breathing or irritation, often caused by histamine.

Edema (Histamine Effect)

Swelling caused by fluid accumulation, a common reaction to histamine release.

Nasal congestion & mucous (Histamine Effect)

Blockage of nasal passages and increased secretions, induced by histamine.

Pruritus (Histamine Effect)

Intense itching, a common skin reaction to histamine.

Skin flushing (Histamine Effect)

Reddening of the skin, often associated with histamine release.

Hypersensitivity Reaction

An exaggerated response by the immune system that produces tissue injury and may cause serious disease; also known as an allergic reaction.

Allergic Reaction

An exaggerated response by the immune system to a substance, producing tissue injury; often interchangeable with hypersensitivity reaction.

Histamine Antagonist

Medications that block the action of histamines by preventing them from binding to their receptors.

Antihistamine

A type of medication that stops the action of histamines, often used to treat allergic symptoms.

Allergic Drug Reactions

Immunologic responses to a medication, causing hypersensitivity symptoms; unpredictable and can occur after first or second exposure.

Anaphylaxis Reactions

Immediate, severe, and potentially life-threatening allergic reactions with symptoms like rash, hives, and difficulty breathing.

Diphenhydramine

An antihistamine (e.g., Benadryl) primarily used for hypersensitivity reactions, motion sickness, insomnia, and Parkinsonism.

Benadryl

A brand name for Diphenhydramine, an antihistamine that prevents/reduces histamine release symptoms without preventing histamine release itself.

Diphenhydramine Mechanism of Action

Prevents or reduces most symptoms of histamine release by blocking receptors, but does not prevent histamine release itself.

Effects of Diphenhydramine

Decreases salivation, tear formation, edema, bronchoconstriction, and pruritus.

CNS Depression (Diphenhydramine)

A common adverse effect, causing symptoms like drowsiness and sedation.

CNS Stimulation (Diphenhydramine)

A less common adverse effect, potentially causing anxiety and agitation.

Anticholinergic Effects (Diphenhydramine)

Side effects such as dry mouth, blurred vision, urinary retention, and constipation.

Diphenhydramine GI Side Effects

Gastrointestinal side effects that can be reduced by taking the medication with milk.

Cetirizine

A second-generation antihistamine (e.g., Zyrtec) used for temporary relief of respiratory allergies and urticaria.

Zyrtec

A brand name for Cetirizine, an antihistamine that effectively binds to histamine receptor sites with less drowsiness due to not crossing the blood-brain barrier.

Loratadine

A second-generation antihistamine (e.g., Claritin) used for temporary relief of respiratory allergies and urticaria.

Claritin

A brand name for Loratadine, an antihistamine that effectively binds to histamine receptor sites with less drowsiness due to not crossing the blood-brain barrier.

Cetirizine/Loratadine Mechanism of Action

Binds to histamine receptor sites to prevent activation; does not readily cross the blood-brain barrier, resulting in less sedation.

Non-drowsy Antihistamines

Antihistamines like Cetirizine and Loratadine that are less likely to cause sedation because they do not easily cross the blood-brain barrier.

Adverse effects of Cetirizine/Loratadine

May include drowsiness (though less common), headache, dizziness, nausea/vomiting, and fatigue.

Fexofenadine

A second-generation antihistamine (e.g., Allegra) used for seasonal allergic rhinitis, minor allergies, and urticaria.

Allegra

A brand name for Fexofenadine, an antihistamine that prevents histamine activation and typically does not cause drowsiness.

Fexofenadine Mechanism of Action

Prevents activation of histamine and does not cross the blood-brain barrier, thus minimizing sedative effects.

Adverse effects of Fexofenadine

Minor side effects may include headache, nausea/vomiting, dysmenorrhea, and fatigue.

Fexofenadine Nursing Consideration

Avoid fruit juice intake due to its potential to decrease the absorption of the drug.

Allergy Rhinitis

A common condition characterized by seasonal allergies, often relieved by antihistamines like Fexofenadine.

Urticaria

Also known as hives, a skin condition characterized by itchy welts, often treated effectively with antihistamines.

MAOIs and Antihistamines

Certain antihistamines, such as Diphenhydramine (Benadryl), should be avoided within 14 days of taking Monoamine Oxidase Inhibitors.

General Antihistamine Assessment

Includes obtaining a comprehensive list of current prescribed, OTC, and herbal medications, and recording baseline vital signs.

Assessing Adverse Effects

Monitoring patients for any undesirable or harmful outcomes resulting from antihistamine therapy.

Assessing Therapeutic Effects

Monitoring patients for the desired positive outcomes of antihistamine therapy, specifically the relief of histamine/allergic symptoms.

Alcohol and Antihistamines

Patients should avoid alcohol consumption when taking antihistamines, especially those known to cause sedation, due to increased CNS depression.

Fluid Intake Recommendation (Antihistamines)

Encourage increased fluid intake, typically 2000-3000 mL daily if not medically contraindicated.

Taking Antihistamines as Directed

Patients should strictly follow prescribed guidelines for medication usage to ensure optimal efficacy and safety.

Dry Mouth (Anticholinergic effect)

A common adverse effect of some antihistamines like Diphenhydramine, characterized by reduced salivary production.

Constipation (Anticholinergic effect)

Difficulty with bowel movements, a potential gastrointestinal side effect of certain antihistamines.

Urinary Retention (Anticholinergic effect)

The inability to completely empty the bladder, a potential genitourinary side effect of some antihistamines.

Blurred Vision (Anticholinergic effect)

Impaired eyesight, a potential ocular side effect of some antihistamines.

Hypersensitivity Reaction Assessment

Standard practice involves directly asking patients about known food, drug, or other allergies upon first contact.

Drug Allergy Timing (First Exposure)

Antibody formation and subsequent allergic reactions typically require a week or longer to develop after initial drug exposure.

Drug Allergy Timing (Most Reactions)

The majority of allergic drug reactions tend to appear within one month of initiating a new medication.

Drug Allergy Specificity

Health care providers are more likely to get complete information by asking about specific drug allergies (e.g., penicillin) rather than general questions.

Suspected Allergic Reaction Interview

If a reaction occurs, nursing assessment includes inquiring about the specific drug, dose, route, and time of administration, and evaluating all concurrent medications.

Outcomes of Therapy (Relief of Symptoms)

A primary goal of antihistamine therapy is for the patient to experience a significant reduction in allergic discomfort and associated symptoms.

Avoiding Hazardous Activities

Patients experiencing sedation from antihistamines must be advised to avoid activities requiring mental alertness, such as driving or operating machinery.

Medical Alert Device

Patients with known drug allergies should be encouraged to carry a medical alert device that clearly identifies the offending drug.

Monitoring for Excessive Drowsiness

A crucial nursing intervention, especially during the first few days of therapy with sedating antihistamines, to ensure patient safety.

Pre-administration of Antihistamine

Administering an antihistamine before situations known to predictably elicit allergic reactions, such as blood transfusions or diagnostic tests involving contrast media.

Emergency Plan for Children with Allergies

Establishing and providing a detailed emergency plan to all family members, daycare staff, and school personnel when a child has known allergies.

Patient Evaluation (Antihistamines)

Observing for the relief of symptoms, verifying correct drug usage, and monitoring for any signs of excessive drowsiness to assess therapy effectiveness and safety.