ß-blockers are contraindicated in

Correct Answer: D

Rationale: Rationale: ß-blockers are a class of drugs commonly used to treat conditions like hypertension, angina, and arrhythmias by blocking the effects of adrenaline on beta receptors. In the context of contraindications, it is crucial to understand the pharmacological effects of ß-blockers. Option A) Prophylaxis of anxiety states: ß-blockers are actually used off-label to manage symptoms of anxiety, as they can help reduce the physical symptoms of anxiety like tremors and palpitations. This option is not contraindicated. Option B) Hyperthyroidism: ß-blockers are often used in hyperthyroidism to manage symptoms like tachycardia and tremors. They do not treat the underlying thyroid condition but can alleviate symptoms. Option C) Hypertrophic obstructive cardiomyopathy: In this condition, ß-blockers are actually considered a first-line therapy due to their ability to reduce heart rate and contractility, improving symptoms and outcomes. Option D) Peripheral vascular disease: ß-blockers can worsen symptoms in patients with peripheral vascular disease by causing vasoconstriction and potentially reducing blood flow to the limbs. This is why they are contraindicated in this condition. Educational context: Understanding contraindications of medications is crucial for healthcare providers to ensure safe and effective treatment. In the case of ß-blockers, knowing when not to use them, such as in peripheral vascular disease, can prevent adverse outcomes and guide appropriate treatment choices. This knowledge helps in tailoring treatment plans to individual patient needs and conditions, improving overall patient care.

Correct Answer: C

Rationale: In this question, the correct answer is C) Streptomycin. Streptomycin is an aminoglycoside antibiotic that can potentiate the neuromuscular blockade produced by d-tubocurarine. This interaction occurs because aminoglycosides can interfere with neuromuscular transmission, leading to an accentuated effect when combined with d-tubocurarine, a neuromuscular blocking agent. Now, let's discuss why the other options are incorrect: A) Penicillin G: Penicillin G is not known to accentuate neuromuscular blockade produced by d-tubocurarine. It does not have a significant interaction with d-tubocurarine in this context. B) Erythromycin: Erythromycin is a macrolide antibiotic and does not have a significant impact on neuromuscular blockade produced by d-tubocurarine. D) Chloramphenicol: Chloramphenicol is not associated with accentuating neuromuscular blockade produced by d-tubocurarine. It does not interact in a way that enhances the effects of d-tubocurarine. Educational context: Understanding drug interactions is crucial in clinical practice to prevent adverse effects and ensure safe and effective patient care. Knowing which drugs can potentiate or inhibit the effects of others is essential for healthcare professionals when managing patients receiving multiple medications. This knowledge helps in making informed decisions and providing optimal treatment strategies.

Correct Answer: C

Rationale: In the context of peripheral nervous system drugs, the correct answer to the question is option C) Bronchoconstriction. This side effect is observed specifically with the use of ßblockers and not with other sympathetic blocking agents due to the mechanism of action of ßblockers. ßblockers block beta-adrenergic receptors, including those in the lungs, leading to bronchoconstriction in susceptible individuals, especially those with underlying respiratory conditions like asthma. Option A) Sedation and drowsiness is a common side effect observed with various classes of drugs, not exclusive to ßblockers. Option B) Congestive heart failure is a potential side effect of ßblockers but can also be seen with other medications affecting the heart. Option D) Reflex tachycardia is actually a rebound increase in heart rate that can occur with sudden withdrawal of ßblockers but is not a direct side effect observed only with ßblockers. Understanding the specific side effects of each class of drugs is crucial in clinical practice to make informed decisions regarding treatment options, especially in patients with comorbidities. Educating healthcare professionals and students about these nuances helps in safe prescribing practices and patient management.

Correct Answer: D

Rationale: Catecholamine O-methyltransferase (COMT) is an enzyme responsible for the breakdown of catecholamines such as dopamine, epinephrine, and norepinephrine. In the context of the question, COMT is found in various tissues in the body. The correct answer, option D, "None of the above," is correct because COMT is not limited to any single specific location listed in the options. Option A, "Adrenergic neurone," is incorrect because COMT can be found in adrenergic neurons where it plays a role in the metabolism of catecholamines. Option B, "Brain," is also incorrect because COMT is present in the brain where it participates in the degradation of neurotransmitters. Option C, "Kidney," is incorrect as well because COMT is also found in the kidneys, contributing to the breakdown of catecholamines in this organ. In an educational context, understanding the distribution and function of enzymes like COMT is crucial in pharmacology, especially when studying drugs that target the peripheral nervous system. Knowing where these enzymes are located helps in predicting how drugs may be metabolized and their potential effects on different tissues. This knowledge is essential for healthcare professionals in prescribing medications and managing patients with conditions affecting the peripheral nervous system.

Correct Answer: D

Rationale: Atropine is an antagonist to all types of muscarinic receptors (M1, M2, and M3). Muscarinic receptors are a subtype of acetylcholine receptors found in the peripheral nervous system. Atropine works by blocking these receptors, specifically inhibiting the actions of acetylcholine at these sites. Educationally, understanding the pharmacological action of atropine on muscarinic receptors is crucial for healthcare professionals, particularly those in fields like nursing, pharmacy, and medicine. Atropine is used in various clinical settings to treat bradycardia, organophosphate poisoning, and to dilate pupils during eye exams. Knowing that atropine acts on all muscarinic receptors helps healthcare providers predict its broad effects and potential side effects. Regarding the other options: - M1, M2, and M3 receptors are all valid targets for atropine, so options A, B, and C are incorrect. - By selecting option D, students demonstrate a comprehensive understanding of atropine's mechanism of action on muscarinic receptors, reinforcing the importance of this knowledge in clinical practice.