The nursing instructor prepares to teach student nurses about how mean effective doses of medications are related to clinical practice. As a result of the instruction, what is the best understanding of the student nurses?

Correct Answer: D

Rationale: Mean effective dose (ED50) affects 50% of a population, but individuals vary-some need more or less due to metabolism, weight, or genetics, a clinical reality. Severe side effects aren't 50%-that's toxicity. Ethnic differences influence response, but dose variation is broader. No effect in 50% misreads ED50. Dose adjustment reflects individual pharmacokinetics, key to practice.

Correct Answer: D

Rationale: Oxymetazoline acts fast; adherence prevents rebound . Days is wrong. D ensures safe use, making it key.

Correct Answer: C

Rationale: Nitrous oxide has a high minimum alveolar concentration (MAC >100%), not low, due to low potency, so that's false. Halogenated agents (e.g., isoflurane) have higher brain:blood coefficients, reflecting solubility, making that false. They reduce mean arterial pressure (MAP) proportional to alveolar concentration via vasodilation, a true statement. Nitrous oxide does decrease tidal volume and increase respiratory rate, true. They don't reduce cerebral metabolic rate via blood flow alone but directly. MAP reduction is a key hemodynamic effect, guiding anesthetic depth monitoring.

Correct Answer: B

Rationale: Gentamicin, an aminoglycoside, risks ototoxicity-hearing loss , especially with repeated use. Ethacrynic acid, a loop diuretic, also has ototoxicity potential, compounding risk. Dizziness , nausea , vertigo , and vomiting (E) occur but are less specific. Monitoring hearing is critical in this scenario.

Correct Answer: C

Rationale: Typical antipsychotics block dopamine D2 receptors, causing extrapyramidal symptoms (EPS) like parkinsonism due to dopamine-acetylcholine imbalance in the basal ganglia. Drugs alleviating EPS often restore this balance. Drug A strongly activates dopamine receptors, mimicking dopamine and potentially countering the blockade, but excessive activation risks psychosis. Drug B moderately boosts dopamine and GABA, offering some benefit but less specificity. Drug C potently blocks muscarinic acetylcholine receptors, reducing cholinergic overactivity that emerges from dopamine depletion, a well-established approach (e.g., benztropine) for EPS relief without worsening psychosis. Drug D enhances GABA, unrelated to EPS mechanisms. Drug E mildly activates dopamine and GABA, insufficient for robust relief. Blocking muscarinic receptors directly addresses the cholinergic excess, making it the most effective and clinically validated strategy for EPS management.

Correct Answer: A

Rationale: Vancomycin, a glycopeptide antibiotic, is critical for treating MRSA but carries risks of hypersensitivity reactions (e.g., rashes) and nephrotoxicity (e.g., reduced urine output). The nurse's priority when observing an upper body rash and decreased urine output is to hold the next dose and notify the physician . This action prevents further drug administration that could worsen a potential allergic reaction or kidney damage, both serious adverse effects requiring immediate medical evaluation. An X-ray might assess lung involvement in severe cases but isn't the first step for these symptoms. An antihistamine could treat mild itching but risks masking a systemic reaction, delaying critical care. A urine specimen might confirm renal issues but doesn't address the urgency of stopping the drug. Holding the dose ensures patient safety while awaiting physician guidance, aligning with nursing protocols for adverse drug reactions, making A the most prudent and timely action.

Correct Answer: A

Rationale: Propranolol belongs to the pharmacologic classification of Beta Blockers. Beta blockers work by blocking the action of adrenaline and other stress hormones, specifically by blocking beta receptors. Propranolol, in particular, is a non-selective beta blocker that is commonly used to treat conditions such as hypertension, angina, and arrhythmias. It is also used off-label for anxiety and migraine prevention.

Correct Answer: D

Rationale: Nystatin is an antifungal medication that works by disrupting fungal cell membrane function, specifically targeting ergosterol and causing the formation of pores in the cell membrane, leading to cell death in fungi. It does not inhibit cell wall synthesis, unlike the other options listed.

Correct Answer: D

Rationale: Asthma attacks in this case are driven by inflammation, often mediated by leukotrienes, which are arachidonic acid derivatives. The goal is to reduce the frequency of attacks by targeting this pathway. Aspirin inhibits cyclooxygenase (COX), reducing prostaglandins but not leukotrienes, and may even worsen asthma in some patients. Celecoxib is a selective COX-2 inhibitor, also irrelevant to leukotrienes. Ipratropium is an anticholinergic bronchodilator, effective for acute symptom relief but not prophylaxis via arachidonic acid pathways. Montelukast is a leukotriene receptor antagonist, directly preventing leukotrienes from binding to their receptors, thus reducing inflammation and attack frequency. Zileuton (E), while a leukotriene synthesis inhibitor, isn't the best choice here as the question specifies receptor binding prevention, not synthesis inhibition. Montelukast aligns perfectly with the mechanism described, making it the correct answer.