Which of the following molecular events most likely mediated the positive inotropic action of milrinone?

Correct Answer: A

Rationale: The correct answer is A: Inhibition of phosphodiesterase. Milrinone is a phosphodiesterase inhibitor, which increases cAMP levels, leading to enhanced cardiac contractility. This occurs through the inhibition of the breakdown of cAMP, resulting in increased intracellular calcium levels and improved myocardial function. Choice B is incorrect because while protein kinase can increase cytoplasmic Ca2+, it is not the primary mechanism of milrinone's positive inotropic action. Choice C is incorrect as milrinone does not directly inhibit the Ca2+/Na+ exchanger. Choice D is incorrect as activation of phospholipase A2 is not the mechanism through which milrinone exerts its positive inotropic effects.

Correct Answer: C

Rationale: The correct answer to the question "Tolerance to nitroglycerin may be overcome by" is C) Temporarily discontinuing the drug for one or two weeks. Rationale: Nitroglycerin is a vasodilator commonly used in the treatment of angina pectoris. Over time, patients may develop tolerance to its effects, reducing its efficacy. By temporarily discontinuing the drug for a period of one or two weeks, the body can regain its sensitivity to nitroglycerin, allowing it to work effectively again. This break helps to prevent or reverse the development of tolerance. Option A) Initially using the largest safe dose of the drug is incorrect because increasing the dose does not address tolerance but may lead to increased side effects and potential toxicity. Option B) Using other nitrites is not the preferred method to overcome tolerance to nitroglycerin. While other nitrites may have similar effects, discontinuing nitroglycerin is a more direct approach to addressing tolerance. Option D) Use of higher doses is not the best approach as mentioned earlier. Increasing the dose does not reverse tolerance and may exacerbate side effects without addressing the underlying issue of decreased drug effectiveness. Educational Context: Understanding how tolerance develops and strategies to manage it is crucial in pharmacology. Educating healthcare professionals on the mechanisms of drug tolerance and appropriate interventions, such as temporarily discontinuing the medication, ensures safe and effective patient care. By grasping these concepts, healthcare providers can optimize treatment outcomes and prevent potential complications associated with drug tolerance.

Correct Answer: D

Rationale: Diazoxide is a potent arterial vasodilator used in the emergency treatment of hypertension. The correct answer, option D, states that diazoxide is administered by slow IV injection because the drug is quickly inactivated by serum protein binding. This is crucial because if diazoxide is administered too quickly, it can lead to a rapid drop in blood pressure due to its fast inactivation, causing hypotension and potential adverse effects. Option A is incorrect because diazoxide is not rapidly biotransformed by hepatic microsomal enzymes. Option B is also incorrect as the drug being highly lipid-soluble and deposited in fat does not relate to the need for slow IV administration. Option C is not relevant as hyperglycemia is not a primary concern when administering diazoxide for hypertension. In an educational context, understanding the pharmacokinetics of cardiovascular drugs like diazoxide is crucial for healthcare professionals to ensure safe and effective administration. Knowing why a drug is administered in a specific manner can prevent adverse reactions and optimize patient outcomes. Slow IV administration of diazoxide is a key clinical consideration that aligns with its pharmacological properties to prevent sudden drops in blood pressure.

Correct Answer: B

Rationale: The correct answer is B) It decreases heart rate and the work of the heart. Beta blockers are a class of drugs that work by blocking the effects of adrenaline on the beta receptors in the heart. By doing so, beta blockers reduce the heart rate, decrease the force of contractions, and lower blood pressure. This helps the heart by reducing its workload and oxygen demand, making it especially beneficial in conditions like hypertension, angina, and heart failure. Option A) It increases preload is incorrect because beta blockers actually reduce preload by lowering heart rate and decreasing the volume of blood returning to the heart, which in turn reduces the workload on the heart. Option C) It increases blood pressure is incorrect because beta blockers are commonly used to lower blood pressure by decreasing the heart rate and the force of contraction, leading to a decrease in cardiac output. Option D) It can be used for ventricular tachycardia is incorrect because beta blockers are not typically the first-line treatment for ventricular tachycardia. They are more commonly used for conditions like atrial fibrillation or to prevent recurrent heart attacks. Understanding the mechanism of action of beta blockers is vital for healthcare professionals as it allows them to make informed decisions regarding the appropriate use of these medications in various cardiovascular conditions. Patients must also be educated about the effects and potential side effects of beta blockers to ensure compliance and optimal outcomes in their treatment.

Correct Answer: C

Rationale: In this scenario, option C) Antibody production against the streptokinase is the correct answer. When a client is on streptokinase for a blood clot, the nurse should be vigilant for the development of antibodies against the medication. This adverse reaction can lead to inactivation of the streptokinase, reducing its effectiveness in dissolving the clot. Option A) Pulmonary embolism is not the correct answer because streptokinase is actually used to treat blood clots, including those causing pulmonary embolism, so this would not be an adverse reaction. Option B) Acute myocardial infarction is also an incorrect choice as streptokinase is used to help dissolve blood clots and reduce the risk of heart attacks, so this would not be an expected adverse reaction. Option D) Acute gastric irritation is not a common adverse reaction associated with streptokinase therapy, making it an incorrect option in this case. Educationally, understanding the potential adverse reactions of cardiovascular drugs is crucial for nurses to provide safe and effective care to their patients. By knowing the possible side effects, nurses can monitor for them, intervene promptly, and educate patients on what to watch out for during their medication therapy.