NEET-PG 2013 Practice Questions

Q: What is the most appropriate initial management for paralysis resulting from organophosphorus poisoning?

Supportive care, including respiratory support. **Supportive care, including respiratory support** * **Paralysis** in organophosphorus poisoning (OPP) is often due to **nicotinic effects** at the neuromuscular junction, leading to respiratory muscle weakness and failure [2]. * **Respiratory support** through mechanical ventilation is crucial to maintain oxygenation and prevent complications while awaiting the effects of antidotal therapy [1], [2]. * *Atropine to counteract muscarinic symptoms* * **Atropine** primarily blocks **muscarinic receptors**, effectively treating symptoms like bradycardia, bronchorrhea, and miosis [2]. * It does **not reverse the nicotinic effects** responsible for muscle paralysis and respiratory failure. * *Oximes to reactivate acetylcholinesterase* * **Oximes (e.g., pralidoxime)** reactivate **acetylcholinesterase**, thereby addressing the underlying cause of acetylcholine accumulation [2]. * They are most effective if given **early** before irreversible aging of the enzyme occurs, but their effect on established paralysis can be limited without concurrent respiratory support [2]. * *No specific antidote* * This statement is incorrect; **atropine** and **oximes** are specific antidotes for organophosphorus poisoning [2]. * While these antidotes are vital, initial management prioritizing **airway and breathing support** is paramount due to the life-threatening respiratory paralysis [1].

Q: Besides its properties of decreasing intraocular pressure, timolol is preferred in the treatment of glaucoma because it

Produces no miosis. ***Produces no miosis*** - Timolol, a **non-selective beta-blocker**, decreases intraocular pressure without affecting pupillary size. - This is a **key advantage** in glaucoma treatment as miosis (pupil constriction) can worsen vision, especially in patients with cataracts. - Unlike **miotics** (e.g., pilocarpine), timolol does not cause pupillary constriction, making it better tolerated. *Possesses membrane stabilizing activity* - While some beta-blockers possess **membrane-stabilizing activity** (local anesthetic effect), this property is not a primary reason for timolol's preference in glaucoma. - This action is more relevant in antiarrhythmic uses of beta-blockers due to its effect on cardiac action potentials. *Increases outflow of aqueous humor* - Timolol primarily reduces intraocular pressure by **decreasing the production of aqueous humor**, not by increasing its outflow. - Drugs like **pilocarpine** (a cholinergic agonist) or **prostaglandin analogs** increase outflow. *Is a selective beta-adrenoceptor blocker* - Timolol is a **non-selective beta-blocker**, meaning it blocks both beta-1 and beta-2 adrenergic receptors. - Its non-selectivity is associated with systemic side effects (e.g., bronchospasm, bradycardia), and selective beta-blockers like **betaxolol** exist but are not the primary reason for timolol's preference in glaucoma.

Q: Which of the following is a second-generation beta blocker?

Atenolol. ***Atenolol*** - **Atenolol** is a **second-generation beta blocker** characterized by its **cardioselectivity**, meaning it primarily blocks beta-1 receptors in the heart. - This selectively reduces heart rate and contractility with fewer respiratory side effects compared to non-selective agents. *Propranolol* - **Propranolol** is a **first-generation non-selective beta blocker**, meaning it blocks both beta-1 and beta-2 adrenergic receptors. - Its non-selective action can cause significant bronchoconstriction, making it less suitable for patients with respiratory conditions. *Timolol* - **Timolol** is also a **first-generation non-selective beta blocker** commonly used in ophthalmic preparations for glaucoma. - It blocks both beta-1 and beta-2 receptors and does not possess the cardioselectivity of second-generation agents. *Nadolol* - **Nadolol** is another **first-generation non-selective beta blocker** with a long duration of action due to its extensive plasma half-life. - Like other first-generation agents, it lacks cardioselectivity and blocks both beta-1 and beta-2 receptors.

Q: Muscarinic cholinergic receptors are seen at all sites, except?

Neuromuscular junction. ***Neuromuscular junction*** - The **neuromuscular junction** primarily contains **nicotinic cholinergic receptors**, not muscarinic receptors. - Activation of these nicotinic receptors by acetylcholine causes muscle contraction. *Stomach* - The stomach contains **muscarinic M3 receptors** which mediate gastric acid secretion and smooth muscle contraction. - Activation by acetylcholine via the vagus nerve promotes digestion. *CNS* - The **central nervous system** has various subtypes of **muscarinic receptors (M1-M5)** distributed throughout, playing roles in learning, memory, and motor control. - These receptors modulate neuronal excitability and neurotransmitter release. *Glands* - Most exocrine glands (e.g., salivary, lacrimal, sweat glands) are richly supplied with **muscarinic receptors**, primarily **M3**. - Activation leads to increased glandular secretion.

Q: Which of the following statements about clonidine is incorrect?

First line for AMI. ***First line for AMI*** - Clonidine is **not first-line** for **Acute Myocardial Infarction (AMI)** as it can cause **bradycardia** and **hypotension**, potentially worsening cardiac output. - First-line AMI treatments include **thrombolytics**, **antiplatelet agents** (aspirin), **beta-blockers**, and **ACE inhibitors** for optimal cardiac protection. *Alpha 2 receptor agonist* - Clonidine is indeed an **alpha-2 adrenergic receptor agonist** that acts centrally in the **medulla oblongata**. - It reduces **sympathetic outflow** from the CNS, leading to decreased **heart rate**, **blood pressure**, and **peripheral vascular resistance**. *Sudden withdrawal causes rebound hypertension* - Abrupt clonidine discontinuation causes dangerous **rebound hypertension** due to sudden loss of **sympathetic inhibition**. - **Gradual tapering** over 1-2 weeks is essential to prevent this potentially life-threatening complication. *Controls loose motions due to diabetic neuropathy* - Clonidine effectively treats **diabetic diarrhea** by stimulating **alpha-2 receptors** in the enteric nervous system. - It **slows intestinal transit** and **enhances fluid absorption**, making it useful for **autonomic neuropathy-related** gastrointestinal symptoms.

Q: Which of the following is classified as a Type E adverse reaction?

Rebound effect due to drug withdrawal. ***Rebound effect due to drug withdrawal*** - Type E adverse reactions are related to **end-of-treatment effects**, specifically withdrawal phenomena. - The **rebound effect** after drug cessation, such as worsened angina after stopping beta-blockers, is a classic example of a Type E reaction. *Toxicity* - This is a general term for adverse effects from excessive drug doses and is **not a specific type** in the ABCDEF classification. - Dose-dependent toxic effects typically align with **Type A** (augmented) reactions, which are predictable and related to the drug's pharmacology. *Augmented effect* - An **augmented effect** is classified as a Type A adverse drug reaction, meaning it is **dose-dependent**, predictable from the drug's known pharmacology, and common. - Examples include bleeding with anticoagulants or hypotension with antihypertensives. *Teratogenesis* - **Teratogenesis** refers to drug-induced fetal malformations and is categorized as a **Type D** (delayed) adverse drug reaction. - These effects are often severe, occur after prolonged exposure, and are rare.

Q: Which dopamine receptor is known for its inhibitory action in the central nervous system?

Dopamine Receptor D2. ***Dopamine Receptor D2*** - The **D2 receptor** is a member of the D2-like family (D2, D3, D4), which are **G-protein coupled receptors** that inhibit adenylyl cyclase activity. - Its activation typically leads to a **decrease in neuronal excitability** and neurotransmitter release, providing an inhibitory effect in the CNS. *Dopamine Receptor D5* - The **D5 receptor** belongs to the D1-like family (D1, D5), which are **G-protein coupled receptors** that stimulate adenylyl cyclase activity. - Activation of D5 receptors typically leads to **excitatory effects** rather than inhibitory ones in the CNS. *No inhibitory dopamine receptor present* - This statement is incorrect as specific dopamine receptor subtypes, particularly the **D2-like family**, are well-established to exert inhibitory actions in the CNS. - These inhibitory effects are crucial for various physiological processes, including motor control and reward pathways. *Dopamine Receptor D1* - The **D1 receptor** is part of the D1-like family (D1, D5) and is known for its **excitatory effects** in the CNS. - Activation of D1 receptors leads to an **increase in intracellular cAMP** and generally enhances neuronal activity.

Q: In the context of pharmacology, which plasma protein do acidic drugs primarily bind to?

Albumin. ***Albumin*** - **Albumin** is the most abundant plasma protein and has multiple binding sites for a wide range of drugs, particularly **acidic drugs**. - Its high concentration and diverse binding capabilities make it the primary transporter for many **lipophilic** and **anionic drugs**. *Globulin* - **Globulins** are a diverse group of proteins, some of which bind to drugs, but they primarily transport **hormones**, **metals**, and **vitamins**, not acidic drugs. - They are less significant for binding acidic drugs compared to albumin. *α1-acid glycoprotein* - **α1-acid glycoprotein** primarily binds to **basic drugs** due to its numerous acidic residues. - While it plays a crucial role in binding basic compounds, it has limited affinity for acidic drugs. *None of the options* - This option is incorrect because **albumin** is a well-established and significant plasma protein for binding acidic drugs. - Specific plasma proteins are known to bind different types of drugs, and for acidic drugs, albumin is the primary binder.

Q: Which of the following develop first during dependence of a substance ?

Psychological dependence. ***Psychological dependence*** - **Psychological dependence** often develops first, characterized by an emotional need for the substance to experience pleasure or avoid discomfort. - This involves a strong **craving** and compulsive drug-seeking behavior despite negative consequences, driven by the substance's effect on brain reward pathways. *Tolerance* - **Tolerance** means that increasing doses of the substance are required to achieve the same effect previously achieved with lower doses. - While it often develops early in substance use, the initial "need" to use the substance is often psychological before physiological adaptations occur. *Physical dependence* - **Physical dependence** describes the body's physiological adaptation to the substance, leading to withdrawal symptoms if use is stopped or reduced. - It typically develops after consistent, prolonged use and is usually preceded by psychological dependence and often tolerance. *Withdrawal symptoms* - **Withdrawal symptoms** are the physiological and psychological signs that occur when a dependent person stops or drastically reduces their substance intake. - These are a direct manifestation of physical dependence and thus develop once physical dependence has been established.

Question 1

What is the process of Hofmann elimination in organic chemistry?

Accepted Answer

E2 elimination reaction producing the least substituted alkene

Answer

E1 elimination reaction favoring tertiary substrates

Answer

SN1 substitution reaction with carbocation intermediate

Answer

SN2 substitution reaction with inversion of configuration

Question 2

What is the most appropriate initial management for paralysis resulting from organophosphorus poisoning?

Accepted Answer

Supportive care, including respiratory support

Answer

Atropine to counteract muscarinic symptoms

Answer

Oximes to reactivate acetylcholinesterase

Answer

No specific antidote

Question 3

Besides its properties of decreasing intraocular pressure, timolol is preferred in the treatment of glaucoma because it

Accepted Answer

Produces no miosis

Answer

Is a selective beta-adrenoceptor blocker

Answer

Increases outflow of aqueous humor

Answer

Possesses membrane stabilizing activity

Question 4

Which of the following is a second-generation beta blocker?

Accepted Answer

Atenolol

Answer

Timolol

Answer

Nadolol

Answer

Propranolol

Question 5

Muscarinic cholinergic receptors are seen at all sites, except?

Accepted Answer

Neuromuscular junction

Answer

Stomach

Answer

CNS

Answer

Glands

Question 6

Which of the following statements about clonidine is incorrect?

Accepted Answer

First line for AMI

Answer

Alpha 2 receptor agonist

Answer

Sudden withdrawal causes rebound hypertension

Answer

Controls loose motions due to diabetic neuropathy

Question 7

Which of the following is classified as a Type E adverse reaction?

Accepted Answer

Rebound effect due to drug withdrawal

Answer

Toxicity

Answer

Augmented effect

Answer

Teratogenesis

Question 8

Which dopamine receptor is known for its inhibitory action in the central nervous system?

Accepted Answer

Dopamine Receptor D2

Answer

Dopamine Receptor D5

Answer

No inhibitory dopamine receptor present

Answer

Dopamine Receptor D1

Question 9

In the context of pharmacology, which plasma protein do acidic drugs primarily bind to?

Accepted Answer

Albumin

Answer

Globulin

Answer

α1-acid glycoprotein

Answer

None of the options

Question 10

Which of the following develop first during dependence of a substance ?

Accepted Answer

Psychological dependence

Answer

Tolerance

Answer

Physical dependence

Answer

Withdrawal symptoms

NEET-PG 2013

Biochemistry

Internal Medicine

Pharmacology

Psychiatry