Antihistamines & Upper-Respiratory Pharmacology Review

Question-and-answer flashcards covering mechanisms, uses, adverse effects, nursing considerations, patient teaching, and key distinctions between first- and second-generation antihistamines discussed in the lecture.

Which part of the respiratory tract do upper-respiratory drugs primarily treat?

The nose, sinuses, pharynx, and larynx (upper airway).

Which part of the respiratory tract do lower-respiratory drugs primarily treat?

The bronchi, bronchioles, and alveoli (lower airway).

What first-generation antihistamine is highlighted in this lecture and its common brand name?

Diphenhydramine (Benadryl).

What second-generation antihistamine is highlighted in this lecture and its common brand name?

Loratadine (Claritin).

How do antihistamines work?

They block histamine (H1) receptors, reducing inflammation, swelling, and fluid production caused by allergic reactions.

List four common allergic conditions treated with antihistamines.

Allergic rhinitis, allergic sinusitis, allergic conjunctivitis, and urticaria (itchy rash).

Which antihistamine generation is more sedating and more anticholinergic?

First-generation (e.g., diphenhydramine).

State the classic anticholinergic mnemonic for first-generation antihistamine effects.

“Can’t see, can’t pee, can’t poop, dry mouth.”

Why is loratadine preferred for long-term seasonal allergy control?

It causes minimal sedation/anticholinergic effects and is safer for daily use over weeks to months.

Approximately how long may loratadine take to deliver noticeable symptom relief?

Up to about one week; patients should start it before peak allergy exposure.

How often can diphenhydramine typically be dosed?

Every 4–6 hours due to its shorter half-life.

Name three non-allergy uses for diphenhydramine.

Motion sickness, suppression of cough caused by post-nasal drip, and adjunct treatment of Parkinson’s symptoms.

Why can diphenhydramine help Parkinson’s disease symptoms?

Its anticholinergic action lowers excess acetylcholine in the brain, reducing tremor and rigidity.

Which neurotransmitters become imbalanced in Parkinson’s disease?

Dopamine decreases and acetylcholine becomes relatively excessive.

What nursing assessments are critical when administering IM/IV diphenhydramine?

Monitor blood pressure for hypotension and assess for symptom relief of the allergic reaction.

Why should patients on diphenhydramine be placed on fall precautions?

Sedation, dizziness, blurred vision, and orthostatic hypotension increase fall risk.

How much fluid intake is generally recommended to counteract drying effects of antihistamines?

About 2 liters (2,000 mL) per day, unless contraindicated.

Give two teaching points to manage diphenhydramine-related dry mouth.

Increase oral fluids and suck on sugar-free candy or gum.

List four conditions in which first-generation antihistamines are generally contraindicated.

Glaucoma, peptic ulcer disease, urinary retention/BPH, and acute asthma attack.

Why are antihistamines discouraged during an acute asthma attack?

Their drying effect can thicken mucus and worsen airway obstruction.

Identify two groups especially prone to antihistamine adverse effects.

Pediatric patients (possible paradoxical restlessness) and older adults (dizziness, anticholinergic effects).

What common household substances and activities should be avoided when taking first-generation antihistamines?

Alcohol, other CNS depressants, and driving/operating heavy machinery.

Besides medications, name two non-pharmacologic measures to alleviate upper-respiratory allergy symptoms.

Using a humidifier and performing saline nasal irrigation (e.g., neti pot).

Explain why students often confuse antihistamines with decongestants.

Both treat upper-respiratory symptoms, but they have different mechanisms and drug classes; separating them in notes helps avoid mix-ups.

How can loratadine and diphenhydramine be used together for severe allergy days?

Take loratadine daily for baseline control and add a single diphenhydramine dose for breakthrough symptoms.

What are the available routes for diphenhydramine administration?

Oral, intramuscular (IM), and intravenous (IV).

Why should patients seek medical care if OTC antihistamines fail after 7–10 days?

Persistent symptoms may indicate a bacterial infection or another condition requiring different treatment.

What is histamine’s role in an allergic reaction?

It triggers local inflammation, swelling, and fluid leakage, signaling the immune system to respond to an allergen.

Describe how motion sickness is relieved by antihistamines.

By blocking histamine receptors in the stomach and CNS, reducing nausea, vomiting, and vertigo induced by motion.

Which generation of antihistamines lacks significant anticholinergic activity?

Second-generation antihistamines (e.g., loratadine).