The order of paralysis with d-tubocurarine is

Correct Answer: B

Rationale: In the context of drugs affecting the peripheral nervous system, d-tubocurarine is a neuromuscular blocking agent that acts by blocking nicotinic acetylcholine receptors at the neuromuscular junction, leading to muscle paralysis. The correct order of paralysis with d-tubocurarine is option B) Neck, Limbs, Face, Eyes, Pharynx, Trunk Respiratory. This order is based on the progression of muscle weakness seen with d-tubocurarine where muscles in the neck and limbs are affected first, followed by the face and eyes, then the pharynx, and finally leading to respiratory muscle paralysis and potential respiratory failure. Option A is incorrect as it does not follow the typical pattern of paralysis seen with d-tubocurarine. Option C and D are also incorrect as they do not accurately depict the sequential order of muscle paralysis associated with this drug. Understanding the order of paralysis with d-tubocurarine is crucial for healthcare professionals, especially anesthesiologists and critical care providers, as it helps in anticipating and managing potential respiratory complications during anesthesia or mechanical ventilation. It also highlights the importance of monitoring respiratory function closely when using neuromuscular blocking agents.

Correct Answer: A

Rationale: The correct answer is A) Contraction of bronchial smooth muscles. Activation of the sympathetic system leads to the fight-or-flight response in the body. This response includes increased heart rate, pupil dilation, mobilization of energy stores, and bronchodilation. Option A is incorrect because activation of the sympathetic system causes bronchodilation, not bronchial smooth muscle contraction. This dilation allows for increased airflow into the lungs to support increased oxygen needs during stress or exercise. Options B and C are correct physiological responses to sympathetic activation. Gluconeogenesis is the process of creating new glucose from non-carbohydrate sources, while glycogenolysis is the breakdown of glycogen into glucose for energy. Option D, contraction of radial smooth muscle of the iris, is also a correct response to sympathetic activation. This action results in pupil dilation, allowing more light to enter the eye to improve vision during fight-or-flight situations. Understanding the effects of sympathetic activation on different organ systems is crucial in pharmacology when studying drugs that target the peripheral nervous system. This knowledge helps in predicting the physiological responses and potential side effects of these drugs on various body functions.

Correct Answer: D

Rationale: In this question regarding α-adrenoceptor blockers with minimal hepatic biotransformation, the correct answer is D) None of the above. The reason for this is that α-adrenoceptor blockers are not typically metabolized by the liver. Instead, they undergo renal excretion largely unchanged. Therefore, none of the options provided, which are all β-blockers (Atenolol, Labetalol, Metoprolol), fit the criteria of having minimal hepatic biotransformation. Atenolol, Labetalol, and Metoprolol are all β-blockers, not α-adrenoceptor blockers. Atenolol and Metoprolol are primarily metabolized by the liver, so they do not have minimal hepatic biotransformation. Labetalol undergoes significant hepatic metabolism as well, so it also does not have minimal hepatic biotransformation. For educational context, understanding the metabolic pathways of drugs is crucial for pharmacology students and healthcare professionals. Knowing which drugs undergo hepatic metabolism versus renal excretion can impact dosing, drug interactions, and potential toxicities. In this case, recognizing the specific metabolic pathways of α-adrenoceptor blockers versus β-blockers is essential for safe and effective pharmacotherapy.

Correct Answer: B

Rationale: In this question, the correct answer is B) Neostigmine. Neostigmine is known to produce more severe muscarinic side effects compared to the other cholinesterase inhibitors listed. Neostigmine is a quaternary ammonium compound that acts as a reversible acetylcholinesterase inhibitor. It increases the concentration of acetylcholine at the neuromuscular junction, leading to increased stimulation of both muscarinic and nicotinic receptors. This excess stimulation of muscarinic receptors can result in side effects such as bradycardia, bronchoconstriction, excessive salivation, gastrointestinal disturbances, and sweating. Pyridostigmine and Ambenonium are also cholinesterase inhibitors, but they are less likely to cause severe muscarinic side effects compared to neostigmine. Pyridostigmine is commonly used in myasthenia gravis, while Ambenonium is less frequently used due to its longer duration of action. It is important for healthcare professionals, especially those prescribing or administering these medications, to understand the differences in side effect profiles of cholinesterase inhibitors to ensure safe and effective patient care. Understanding these nuances can help in making informed decisions regarding drug selection and management of potential adverse effects.

Correct Answer: C

Rationale: Metoprolol is classified as a cardioselective beta1-blocker, meaning it predominantly acts on beta1-adrenergic receptors in the heart. Option C, "Without membrane stabilizing effect and without partial agonist effect," is the correct choice for several reasons. Firstly, metoprolol does not possess membrane stabilizing effects, which are typically seen in non-selective beta blockers like propranolol that also act on beta2 receptors. Secondly, metoprolol lacks partial agonist activity, indicating that it acts purely as a beta blocker without any intrinsic sympathomimetic activity. Options A, B, and D are incorrect because they include characteristics that do not align with metoprolol's pharmacological profile. For instance, having membrane stabilizing effects (Option A and D) or partial agonist effects (Option A, B, and D) would contradict metoprolol's classification as a cardioselective beta1-blocker. In an educational context, understanding the specific pharmacological properties of drugs like metoprolol is crucial for healthcare professionals to make informed decisions regarding their use in clinical practice. This knowledge helps in selecting the most appropriate medication based on a patient's condition and desired therapeutic outcomes.