The mechanism of action of drugs is best determined by its:

Correct Answer: B

Rationale: Pharmacodynamics refers to the study of how drugs exert their effects on the body, including the interactions between a drug and its target molecule or receptor leading to a biological response. Understanding a drug's mechanism of action involves determining how it interacts with specific receptors, enzymes, ion channels, or other molecular targets within the body to produce the desired therapeutic effects. Pharmacokinetics, on the other hand, involves the study of how drugs move through the body, including their absorption, distribution, metabolism, and excretion, which although important for determining effective drug dosages and concentrations, does not directly provide insight into how a drug exerts its pharmacological effects. Therapeutic action refers to the overall clinical effect of the drug in treating a specific condition, which is influenced by its pharmacodynamics. Pharmaceutical preparations involve drug formulation and delivery methods, such as tablets, injections, or creams, which affect a drug's bioavailability but do not determine its specific mechanism of action.

Correct Answer: B

Rationale: The first pass effect refers to the metabolism of a drug as it passes through the liver before reaching the systemic circulation. When a drug is absorbed from the gut lumen, it first enters the portal circulation where it is transported to the liver. In the liver, the drug may undergo metabolic processes that can reduce the amount of active drug reaching systemic circulation. This process can greatly affect the overall bioavailability and effectiveness of the drug. So, the metabolism of the drug en route from the gut lumen to the systemic circulation is primarily due to the first pass effect.

Correct Answer: B

Rationale: Drugs that block both alpha- and beta-adrenergic receptors are primarily used to treat cardiac-related conditions. Phentolamine, a nonselective alpha-adrenergic blocking agent, is used to treat extravasation of IV norepinephrine or dopamine and hypertension related to a pheochromocytoma. Alpha1-selective adrenergic blocking agents are used for treatment of hypertension and benign prostatic hyperplasia. The beta-adrenergic blocking agents are used to treat cardiovascular problems (hypertension, angina, migraine headaches) and to prevent reinfarction after myocardial infarction. Beta1-selective adrenergic blocking agents are used for treating hypertension, angina, and some cardiac arrhythmias. The nurse should understand the indications for these agents to ensure safe and effective administration.

Correct Answer: B

Rationale: Omeprazole is classified as an antiulcer agent. It belongs to the class of medications known as proton pump inhibitors (PPIs), which work by reducing the production of stomach acid. Omeprazole is commonly used to treat conditions such as gastroesophageal reflux disease (GERD), peptic ulcers, and Zollinger-Ellison syndrome. Its main therapeutic effects include reducing stomach acid secretion and promoting the healing of ulcers.

Correct Answer: D

Rationale: Nesiritide is a recombinant form of human B-type natriuretic peptide (BNP) that is used for the treatment of acutely decompensated heart failure (HF). It is specifically indicated for patients with acute decompensated HF who have dyspnea at rest. Nesiritide works by promoting vasodilation and natriuresis, which helps alleviate symptoms of acute decompensated HF such as dyspnea and edema. Therefore, the patient with acutely decompensated HF who has dyspnea at rest is the best candidate to receive nesiritide therapy to help improve their symptoms and hemodynamic status.