A nurse is analyzing the laboratory studies on a client receiving dantrolene sodium (Dantrium). Which of the following laboratory tests would identify an adverse effect associated with the use of the medication?

Correct Answer: C

Rationale: Dantrolene sodium is associated with hepatotoxicity, making liver function tests essential for monitoring adverse effects. Elevated liver enzymes (ALT, AST) may indicate liver damage, requiring discontinuation of the drug. Blood urea nitrogen and creatinine are used to assess kidney function, while triglyceride levels are unrelated to dantrolene's primary adverse effects. Regular monitoring of liver function is critical to ensure patient safety during treatment.

Correct Answer: D

Rationale: Fatigue, orthostatic hypotension (116/62 to 92/52), hyponatremia (Na+ 132), and hyperkalemia (K+ 5.5) post-mononucleosis suggest Addison's disease (adrenal insufficiency). Fludrocortisone treats mineralocorticoid deficiency but needs diagnosis first. CBT addresses fatigue psychologically, not endocrine causes. Aciclovir treats viral infections, irrelevant here. Tetracosactide (Synacthen) tests adrenal function, diagnosing Addison's by cortisol response, most appropriate to confirm before lifelong therapy. This diagnostic step ensures accurate management, critical in suspected adrenal failure.

Correct Answer: A

Rationale: The extraction ratio (ER = hepatic clearance / liver blood flow) quantifies first-pass metabolism's impact on bioavailability (F = 1 - ER), a true statement. It doesn't directly affect volume of distribution, which is a distribution parameter, so that's false. Oral morphine's bioavailability is ~20-30%, not exactly 15%, but close, though false per key. Phenytoin's extraction ratio is low, not high, due to capacity-limited metabolism. Lidocaine's high first-pass effect prevents oral efficacy, true. The ER formula is foundational in pharmacokinetics, predicting oral drug availability.

Correct Answer: D

Rationale: Pharmacological classification groups drugs by mechanism-anticoagulants influence clotting by inhibiting factors like thrombin, a precise definition. Anti-anginal and antihypertensive describe therapeutic effects, not mechanisms. Calcium channel blockers' action is mechanistic but less broad than clotting's systemic impact. Anticoagulants' specific role in coagulation reflects accurate classification understanding, key for pharmacology learning.

Correct Answer: C

Rationale: Median effective dose (ED50) affects 50% of a population, a statistical pharmacodynamic measure, not individual guarantee. No adverse effects isn't assured-safety varies. Metabolism timing depends on half-life, not ED50. Majority effectiveness exceeds 50%. Half the population defines ED50, explaining its intent.