The nurse administering the phosphodiesterase inhibitor milrinone (Primacor) recognizes that this drug will have a positive inotropic effect. Which result reflects this effect?

Correct Answer: C

Rationale: Step 1: Milrinone is a phosphodiesterase inhibitor that increases intracellular cAMP levels in cardiac myocytes. Step 2: Increased cAMP levels lead to enhanced calcium influx into cardiac cells, increasing contractility. Step 3: Increased force of cardiac contractions (Choice C) is the direct result of enhanced contractility due to increased cAMP levels. Summary: Choice C is correct since milrinone's mechanism of action directly leads to increased force of cardiac contractions. Choices A, B, and D are incorrect as they do not align with milrinone's mechanism of action and its inotropic effect.

Correct Answer: C

Rationale: The correct answer is C: Fraction of an uncharged drug reaching the systemic circulation following any route administration. Bioavailability refers to the percentage of an administered drug that reaches the systemic circulation in an unchanged form. This definition excludes options A, B, and D as they do not directly relate to the concept of bioavailability. Plasma protein binding (A) refers to the extent to which a drug binds to proteins in the blood, brain-blood barrier permeability (B) is related to drug penetration into the brain, and the amount of a substance in urine relative to the initial dose (D) is more related to drug excretion rather than bioavailability. Thus, option C is correct as it specifically describes the concept of bioavailability.

Correct Answer: D

Rationale: The correct answer is D because all the substances listed interact with ion channels. Sodium channel blockers inhibit sodium influx, calcium channel blockers block calcium entry, and potassium channel activators enhance potassium efflux. A and B specifically target ion channels, while C indirectly influences ion channels through potassium activation. Therefore, all choices align with ion channel interactions.

Correct Answer: D

Rationale: The correct answer is D because the choice of a local anesthetic for specific procedures should consider multiple factors, including the duration of action (A), water solubility (B), and the capability of rapid penetration through the skin or mucosa with limited diffusion away from the site of application (C). Duration of action is important for ensuring adequate pain relief during the procedure, water solubility affects the onset of action and tissue penetration, and limited diffusion helps in maintaining the anesthetic effect at the target site. Therefore, considering all these factors collectively ensures the most appropriate choice of local anesthetic for a specific procedure. Choices A, B, and C on their own do not encompass all the essential considerations for selecting a local anesthetic, making them incorrect.

Correct Answer: B

Rationale: Rationale: 1. Atropine is a muscarinic receptor antagonist. 2. It competes with pilocarpine and choline esters for the muscarinic receptors. 3. By binding to the receptors, atropine blocks the excessive stimulation. Summary: - A: Edrophonium is an acetylcholinesterase inhibitor, not a muscarinic receptor antagonist. - C: Pralidoxime is used to treat organophosphate poisoning, not muscarinic receptor overstimulation. - D: Echothiophate is a long-acting acetylcholinesterase inhibitor, not a muscarinic receptor antagonist.