A hypertensive patient has been using nifedipine for some time without untoward effects. If he experiences a rapidly developing enhancement of the antihypertensive effect of the drug, it is probably due to

Correct Answer: C

Rationale: The correct answer is C) Grapefruit juice. Grapefruit juice contains compounds that inhibit the enzyme CYP3A4 in the intestine, which is responsible for metabolizing nifedipine. When this enzyme is inhibited, more of the drug is absorbed into the bloodstream, leading to a higher concentration of nifedipine, thus enhancing its antihypertensive effect. Option A) Concomitant use of antacids: Antacids typically do not have a significant interaction with nifedipine that would lead to a rapid enhancement of its antihypertensive effect. Option B) Foods containing tyramine: Tyramine-containing foods are known to interact with certain classes of drugs, like MAOIs, but not with nifedipine in a way that would rapidly enhance its antihypertensive effect. Option D) Induction of drug metabolism: Inducing drug metabolism would typically lead to a decrease in drug levels, not a rapid enhancement of its effects as seen in the scenario described. Educational context: Understanding drug interactions is crucial in clinical practice to ensure patient safety and optimal therapeutic outcomes. Healthcare providers need to be aware of how different substances can affect drug metabolism and efficacy to make informed decisions when managing patients on multiple medications. This case highlights the importance of considering dietary factors, like grapefruit juice, in medication management for individuals on nifedipine therapy.

Correct Answer: C

Rationale: In this scenario, the correct answer is C) Probably be the result of drug-induced heart block. This is the correct response because cardiac glycosides, such as digoxin, can cause bradycardia by affecting the electrical conduction system of the heart, leading to heart block. This results in a slower heart rate, which in this case has decreased from 86/min to 40/min. Option A) Probably be unrelated to drug administration is incorrect because the sudden significant decrease in heart rate after starting cardiac glycoside treatment is likely related to the drug's effect on the heart's conduction system. Option B) Be the desired response of the drug is incorrect as while cardiac glycosides aim to improve cardiac function in CHF by increasing contractility, a drastic drop in heart rate like in this case is not the primary desired response of the drug. Option D) Be an indication for increasing the drug dose is incorrect because a decreased heart rate in this scenario is actually a sign of potential toxicity rather than a need for increased dosage. Educationally, this question highlights the importance of understanding the mechanisms of action and potential side effects of cardiovascular drugs, emphasizing the need for careful monitoring and dose adjustments to ensure patient safety and optimal treatment outcomes.

Correct Answer: A

Rationale: In this scenario, the correct answer is A) Shock. When a client is in shock, their blood pressure drops significantly, and their tissues do not receive an adequate supply of oxygenated blood. Beta agonists, such as epinephrine, can be used to increase heart rate and contractility, helping to improve cardiac output and blood pressure in cases of shock. Option B) Hypertension is incorrect because beta agonists can actually worsen hypertension by increasing heart rate and blood pressure, which is counterproductive in this condition. Option C) Cardiac arrhythmias is incorrect because while beta blockers are often used to manage certain types of arrhythmias, beta agonists can exacerbate arrhythmias by increasing heart rate and contractility. Option D) Supraventricular tachycardia is incorrect because beta agonists can further increase heart rate in this condition, potentially worsening the tachycardia. From an educational perspective, understanding the appropriate use of beta agonists is crucial for healthcare providers. It is essential to know the specific conditions where beta agonists are indicated, such as shock, and when they should be avoided or used with caution to prevent potential complications. This knowledge ensures safe and effective medication administration and optimal patient outcomes.

Correct Answer: D

Rationale: The correct answer is D) Abciximab. Abciximab is a glycoprotein IIB/IIIA receptor antagonist that is used for the prevention of stroke in certain high-risk patients. This drug works by inhibiting platelet aggregation, reducing the risk of clot formation and subsequent stroke. A) Plavix (clopidogrel) is a P2Y12 inhibitor, not a glycoprotein IIB/IIIA receptor antagonist. It is commonly used for preventing heart attacks and strokes in patients with cardiovascular diseases. B) Ticlid (ticlopidine) is another P2Y12 inhibitor, similar to Plavix. It is also used to prevent strokes in patients at risk of clot-related events. C) Aspirin is an antiplatelet drug that works by inhibiting the formation of thromboxane, another pathway involved in platelet aggregation. While aspirin is commonly used for stroke prevention, it does not specifically target the glycoprotein IIB/IIIA receptor like Abciximab does. Educational context: Understanding the mechanisms of action of different cardiovascular drugs is crucial for healthcare professionals to make informed decisions when managing patients with cardiovascular conditions. Knowing the specific indications, contraindications, and side effects of each drug class helps in providing optimal care and preventing adverse events. In this case, recognizing the role of glycoprotein IIB/IIIA receptor antagonists in stroke prevention highlights the importance of tailored pharmacological interventions based on individual patient needs and risk factors.

Correct Answer: D

Rationale: In this scenario, the correct answer is D) Reserpine. Reserpine works by blocking the Mg²⁺/ATP-dependent transport of biogenic amines, such as norepinephrine and dopamine, from the cytoplasm into storage vesicles in adrenergic nerves. By inhibiting this process, reserpine reduces the amount of norepinephrine available for release, leading to decreased sympathetic tone and ultimately lowering blood pressure. Now let's analyze why the other options are incorrect: A) Atenolol is a beta-blocker that works by blocking beta-adrenergic receptors, not by affecting the transport of biogenic amines. B) Esmolol is a short-acting beta-blocker used for acute management of hypertension and supraventricular tachycardia, but it does not act on biogenic amine transport. C) Guanethidine blocks the release of norepinephrine from sympathetic nerve terminals rather than affecting its transport into storage vesicles. In an educational context, understanding how different cardiovascular drugs work is crucial for healthcare providers to make informed decisions when managing patients with hypertension or other cardiovascular conditions. Knowing the mechanisms of action of drugs like reserpine can help optimize therapy and minimize adverse effects. This case highlights the importance of pharmacological knowledge in tailoring treatment regimens for individual patients based on their unique characteristics and needs.