DO Osteopathic Pharmacology 3

Question 1

A patient on digoxin for heart failure develops nausea, yellow-green visual disturbances, and arrhythmias. Which electrolyte abnormality most potentiates digoxin toxicity?

Accepted Answer

Hypokalemia

Answer

Hypernatremia

Answer

Hyperkalemia

Answer

Hypophosphatemia

Question 2

A patient is being switched from fluoxetine to phenelzine. Why must a 5-week washout period be observed before starting the MAOI?

Accepted Answer

Fluoxetine and its active metabolite norfluoxetine have exceptionally long half-lives

Answer

Fluoxetine irreversibly inhibits MAO enzymes for 5 weeks

Answer

Fluoxetine induces hepatic enzymes that activate phenelzine to toxic metabolites

Answer

Fluoxetine permanently occupies serotonin transporters for several weeks

Question 3

A 68-year-old man with both hypertension and benign prostatic hyperplasia (BPH) asks about a single drug that can treat both conditions. Which drug class is appropriate?

Accepted Answer

Alpha-1 adrenergic blockers

Answer

Selective beta-1 blockers

Answer

ACE inhibitors

Answer

Non-dihydropyridine calcium channel blockers

Question 4

Which immunosuppressant used in solid organ transplantation works by forming a complex with cyclophilin that inhibits calcineurin?

Accepted Answer

Cyclosporine

Answer

Azathioprine

Answer

Mycophenolate mofetil

Answer

Sirolimus (rapamycin)

Question 5

A patient with Parkinson's disease is prescribed levodopa/carbidopa. Why is carbidopa included in the formulation?

Accepted Answer

Carbidopa inhibits peripheral DOPA decarboxylase, preserving levodopa for CNS conversion

Answer

Carbidopa crosses the blood-brain barrier and converts to dopamine centrally

Answer

Carbidopa blocks central dopamine receptors to modulate levodopa effect

Answer

Carbidopa prevents renal excretion of levodopa

Question 6

What is the mechanism by which unfractionated heparin exerts its anticoagulant effect?

Accepted Answer

Potentiates antithrombin III, accelerating inactivation of thrombin and factor Xa

Answer

Directly inhibits thrombin and factor Xa independently

Answer

Inhibits vitamin K-dependent synthesis of clotting factors II, VII, IX, and X

Answer

Blocks fibrin polymerization by binding fibrinogen

Question 7

A patient on high-dose atorvastatin develops muscle pain and markedly elevated creatine kinase (CK). Which mechanism best explains statin-induced myopathy?

Accepted Answer

Depletion of coenzyme Q10 via mevalonate pathway inhibition impairing mitochondrial function

Answer

Direct membrane toxicity from accumulation of hydrophilic statin metabolites

Answer

Immune-mediated necrotizing myopathy triggered by anti-HMGCR antibodies

Answer

Impaired sarcoplasmic reticulum calcium release causing muscle fiber contracture