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: Hurthle cell carcinoma is a variant of which type of carcinoma?

Follicular carcinoma. **Follicular carcinoma** - **Hürthle cell carcinoma**, also known as **oxyphilic follicular carcinoma**, is a specific variant of **follicular carcinoma of the thyroid**. - It is characterized by the presence of large polygonal cells with abundant eosinophilic, granular cytoplasm known as **Hürthle cells** (or oxyphil cells) within the neoplastic growth. *Medullary carcinoma* - **Medullary carcinoma** originates from the **parafollicular C cells** of the thyroid, which produce calcitonin. - It is histologically distinct, featuring nests or cords of cells often associated with **amyloid deposits**, and is not related to Hürthle cell morphology. *Papillary carcinoma* - **Papillary carcinoma** is the most common type of thyroid cancer, characterized by distinctive **nuclear features** such as **Orphan Annie eye nuclei**, nuclear grooves, and intranuclear cytoplasmic inclusions. - Its histological origin and morphological appearance are different from Hürthle cell neoplasms, which are follicular in origin. *Anaplastic carcinoma* - **Anaplastic carcinoma** is a highly aggressive and undifferentiated thyroid malignancy with a very poor prognosis. - It is characterized by pleomorphic, giant, and spindle cells and lacks the specific differentiation seen in follicular or Hürthle cell tumors.

Q: When two different chemicals act on two different receptors and their responses are opposite to each other on the same cell, this phenomenon is called?

Physiological antagonism. ***Physiological antagonism*** - This occurs when two drugs act on **different receptors** to produce **opposite physiological effects** within the same system or cell, effectively canceling each other out [1]. - A classic example is the opposing actions of **histamine** (causing bronchoconstriction) and **adrenaline** (causing bronchodilation) on the bronchi [1]. *Chemical antagonism* - This involves a direct **chemical interaction** between two drugs that results in the **inactivation of one or both** of them. - An example is the binding of **chelating agents** to heavy metals, forming an inert complex. *Reversible antagonism* - This describes antagonism where the antagonist binds to the receptor and can be **displaced by a higher concentration of the agonist**. - It does not specifically describe antagonists acting on different receptors or producing opposing physiological effects. *Competitive antagonism* - This occurs when an antagonist directly **competes with an agonist for the same binding site** on a receptor [1]. - The antagonist, while not producing a response itself, prevents the agonist from binding and activating the receptor.

Q: Which of the following factors influences the duration of action of a drug?

All of the options. ***All of the options*** - **Clearance** and **rate of elimination** are the primary determinants of how long a drug stays in the body at therapeutic levels, thus directly influencing its duration of action. - **Bioavailability** affects the intensity and onset but can influence the perceived duration if subtherapeutic concentrations are achieved. - The interplay of these pharmacokinetic parameters ultimately determines the drug's therapeutic window and frequency of dosing. *Clearance* - **Clearance** is the rate at which the active drug is removed from the body, primarily by the kidneys and liver. - A higher clearance generally leads to a shorter elimination half-life and a **shorter duration of action**, as the drug is removed more quickly from the systemic circulation. *Rate of elimination* - The **rate of elimination** directly dictates how quickly the concentration of a drug in the body decreases over time. - A faster elimination rate (shorter half-life) means the drug's effects will wear off sooner, resulting in a **shorter duration of action**. - This is quantified by the elimination rate constant (Kel) and half-life (t½). *Bioavailability* - **Bioavailability** refers to the fraction of an administered dose of unchanged drug that reaches the systemic circulation. - While bioavailability primarily affects the **peak concentration (Cmax)** and **intensity** of drug effect, it can indirectly influence duration. - If bioavailability is very low, therapeutic concentrations may not be sustained long enough, effectively shortening the **clinically relevant duration of action**. - However, two drugs with identical elimination rates but different bioavailabilities will have the same elimination half-life and similar duration at therapeutic doses.

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 urinary bladder spasmolytic has local anesthetic properties?

Oxybutynin. ***Oxybutynin*** - Possesses both **anticholinergic properties** (bladder smooth muscle relaxation) and **direct local anesthetic properties**, which contribute to its spasmolytic effect on the detrusor muscle. - The **local anesthetic action** directly reduces bladder detrusor muscle contractions, explaining its efficacy in treating urge incontinence and overactive bladder. - This dual mechanism makes it unique among bladder spasmolytics. *Tamsulosin* - Is an **alpha-1 adrenergic receptor blocker** used for benign prostatic hyperplasia (BPH) by relaxing smooth muscle in the prostate and bladder neck. - Does **not have local anesthetic properties** and is not a bladder detrusor spasmolytic. *Terazosin* - Also an **alpha-1 adrenergic receptor blocker**, similar to tamsulosin, used for BPH and hypertension. - Acts via **vascular and prostatic smooth muscle relaxation**, without local anesthetic or bladder spasmolytic effects. *Yohimbine* - Is an **alpha-2 adrenergic receptor antagonist** known for increasing sympathetic outflow. - Does **not have bladder spasmolytic effects** or local anesthetic properties.

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: Which of the following is classified as an antispasmodic agent?

Dicyclomine. ***Dicyclomine*** - **Dicyclomine** is an **anticholinergic** medication that works by blocking muscarinic receptors, thereby reducing smooth muscle spasm in the gastrointestinal tract. - It is commonly used to treat symptoms of **irritable bowel syndrome (IBS)**, such as abdominal pain and cramping. *Physostigmine* - **Physostigmine** is a **cholinesterase inhibitor** that increases the concentration of acetylcholine at the synaptic cleft. - It is used to treat **anticholinergic poisoning** by reversing the effects of anticholinergic drugs, rather than acting as an antispasmodic itself. *Tropicamide* - **Tropicamide** is an **anticholinergic** agent primarily used as a **mydriatic** (pupil dilator) and **cycloplegic** (paralyzes the ciliary muscle) for ophthalmic examinations. - Its action is localized to the eye and it does not have significant systemic antispasmodic effects. *None of the options* - This option is incorrect because one of the listed medications is indeed classified as an antispasmodic agent. - When "None of the options" appears as a choice, it should only be selected if all other options are clearly incorrect.

Q: Which of the following is not a recognized use of alpha-2-agonists?

Benign Hyperplasia of prostate. ***Correct Answer: Benign Hyperplasia of prostate*** - Alpha-2-agonists are **NOT** used to treat **benign prostatic hyperplasia (BPH)**; this condition is typically managed with **alpha-1-blockers** (e.g., tamsulosin, alfuzosin) or 5-alpha-reductase inhibitors. - Alpha-1-blockers relax the smooth muscle in the prostate and bladder neck, improving urine flow, which involves a different receptor mechanism than alpha-2-agonists. - Alpha-2-agonists would not provide therapeutic benefit for BPH. *Incorrect: Glaucoma* - Alpha-2-agonists (e.g., **brimonidine**, **apraclonidine**) **are** used to treat **glaucoma** by reducing aqueous humor production and increasing uveoscleral outflow. - This action helps to **lower intraocular pressure**, a primary goal in glaucoma management. *Incorrect: Hypertension* - Central-acting alpha-2-agonists (e.g., **clonidine**, **methyldopa**) **are** used as **antihypertensive agents**. - They reduce sympathetic outflow from the central nervous system, leading to decreased heart rate, vasodilation, and consequently, **lower blood pressure**. *Incorrect: Sedation* - Alpha-2-agonists like **dexmedetomidine** and **clonidine** **are** commonly used for **sedation** in critically ill patients, especially in intensive care units. - They produce sedation, analgesia, and anxiolysis without causing significant respiratory depression, making them valuable in certain clinical settings.

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

Hurthle cell carcinoma is a variant of which type of carcinoma?

Accepted Answer

Follicular carcinoma

Answer

Medullary carcinoma

Answer

Papillary carcinoma

Answer

Anaplastic carcinoma

Question 4

When two different chemicals act on two different receptors and their responses are opposite to each other on the same cell, this phenomenon is called?

Accepted Answer

Physiological antagonism

Answer

Chemical antagonism

Answer

Reversible antagonism

Answer

Competitive antagonism

Question 5

Which of the following factors influences the duration of action of a drug?

Accepted Answer

All of the options

Answer

Bioavailability

Answer

Clearance

Answer

Rate of elimination

Question 6

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 7

Which urinary bladder spasmolytic has local anesthetic properties?

Accepted Answer

Oxybutynin

Answer

Tamsulosin

Answer

Terazosin

Answer

Yohimbine

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

Which of the following is classified as an antispasmodic agent?

Accepted Answer

Dicyclomine

Answer

Physostigmine

Answer

Tropicamide

Answer

None of the options

Question 10

Which of the following is not a recognized use of alpha-2-agonists?

Accepted Answer

Benign Hyperplasia of prostate

Answer

Glaucoma

Answer

Hypertension

Answer

Sedation

NEET-PG 2013

Biochemistry

Internal Medicine

Pathology

Pharmacology