NEET-PG 2015 - Pharmacology Practice Questions

Q: Which anti-cholinesterase drug is known for its central nervous system activity?

Physostigmine. ***Physostigmine*** - Unlike most other anti-cholinesterases, **physostigmine** is a **tertiary amine** and is relatively lipid-soluble, allowing it to cross the **blood-brain barrier**. [2] - Its ability to increase acetylcholine in the CNS makes it useful in treating anticholinergic toxicity (e.g., atropine overdose). [2] *Pyridostigmine* - **Pyridostigmine** is a **quaternary amine** and does not readily cross the blood-brain barrier, primarily acting peripherally. - It is mainly used in the long-term management of **myasthenia gravis**. *Edrophonium* - **Edrophonium** is a very short-acting **quaternary amine** that does not cross the blood-brain barrier. [1] - It is primarily used for the **diagnosis of myasthenia gravis** (Tensilon test) due to its rapid onset and short duration of action. [1] *Neostigmine* - **Neostigmine** is also a **quaternary amine** with poor lipid solubility, meaning it has minimal central nervous system activity. [2] - It is commonly used to reverse the effects of **non-depolarizing neuromuscular blockers** and in the treatment of **myasthenia gravis**.

Q: What is a contraindication of antimuscarinic drugs?

Glaucoma. ***Correct: Glaucoma*** - Antimuscarinic drugs cause **mydriasis (pupil dilation)** and **cycloplegia**, which increases intraocular pressure, especially in individuals with **narrow-angle glaucoma**. - In narrow-angle glaucoma, pupil dilation causes the peripheral iris to bunch up and block the trabecular meshwork, obstructing aqueous humor outflow. - This can precipitate an **acute angle-closure glaucoma attack**, a medical emergency, making glaucoma an **absolute contraindication** to antimuscarinic drugs. - This is one of the most important contraindications to remember for all anticholinergic medications. *Incorrect: Peptic ulcer* - Antimuscarinic drugs were **historically used to treat** peptic ulcer disease by reducing gastric acid secretion and gastrointestinal motility. - While they are no longer first-line therapy (replaced by proton pump inhibitors and H2 blockers), peptic ulcer is **not a contraindication**. - The main reason they fell out of favor was due to side effects and less efficacy compared to modern alternatives, not because they worsen the condition. *Incorrect: Asthma* - Some antimuscarinics (e.g., **ipratropium, tiotropium**) are actually used as **bronchodilators** in asthma and COPD management. - They work by blocking muscarinic receptors in airway smooth muscle, causing bronchodilation. - Therefore, asthma is a **treatment indication**, not a contraindication. *Incorrect: Urinary incontinence* - Antimuscarinic drugs are the **primary pharmacological treatment** for overactive bladder and urge incontinence. - They work by blocking M3 muscarinic receptors in the detrusor muscle, reducing bladder contractions. - Common drugs include oxybutynin, tolterodine, and solifenacin. - Urinary incontinence is a **treatment indication**, not a contraindication.

Q: Maximum cycloplegic action of atropine is seen at ?

1-3 hours. ***1-3 hours*** - Atropine, a **non-selective muscarinic antagonist**, reaches its **peak cycloplegic effect** approximately 1 to 3 hours after topical administration. - This peak activity is crucial for accurate retinoscopy and **refractive error measurement** in children, as it effectively paralyzes the ciliary muscle. *4-6 hours* - While atropine's cycloplegic effect is still present at 4-6 hours, it is generally **past its peak action** by this time. - Slower-acting cycloplegics might have their peak around this window, but not atropine. *1-2 weeks* - The **duration of action** for atropine's cycloplegic and mydriatic effects can last for 1-2 weeks, but this is the total duration, not when the maximum action is observed. - Patients are often instructed about the **prolonged effects** and potential for blurred vision and photophobia over this period. *30-60 minutes* - While some mydriatic effects might start within 30-60 minutes, the **full cycloplegic effect** of atropine, which requires maximum paralysis of the ciliary muscle, is not achieved in this short timeframe. - Shorter-acting cycloplegics like **cyclopentolate** or **tropicamide** would show peak action within this earlier interval.

Q: Which of the following is NOT a side effect of atropine?

Diarrhoea. ***Diarrhoea*** - Atropine is a **muscarinic antagonist** that blocks the action of **acetylcholine** on muscarinic receptors in the gastrointestinal tract. - This leads to **decreased GI motility** and **decreased secretions**, typically causing **constipation**, NOT diarrhoea. - Diarrhoea would be associated with **cholinergic agonists** or anticholinesterases, which increase GI motility. *Blurring of vision* - Atropine causes **mydriasis** (pupil dilation) and **cycloplegia** (paralysis of the ciliary muscle). - **Cycloplegia** impairs accommodation for near vision, leading to **blurring of vision**. - This is a common anticholinergic side effect. *Urinary retention* - Atropine blocks **M3 receptors** on the **detrusor muscle**, causing bladder relaxation and reduced contractility. - This leads to **urinary retention**, especially in patients with pre-existing conditions like **prostatic hypertrophy**. *Confusion in elderly* - Atropine can cross the **blood-brain barrier** and cause **CNS effects** including confusion, agitation, and delirium. - Elderly patients are particularly susceptible to these **central anticholinergic effects**.

Q: Which antimuscarinic drug is used in overactive bladder?

Trospium. ***Trospium*** - **Trospium** is a quaternary ammonium compound that acts as an **antimuscarinic agent** primarily used to treat **overactive bladder (OAB)**. - Its **polar nature** limits its ability to cross the blood-brain barrier, reducing central nervous system side effects common with other antimuscarinics. *Tropicamide* - **Tropicamide** is an **antimuscarinic** agent primarily used as a **mydriatic** (to dilate pupils) and **cycloplegic** (to paralyze the ciliary muscle) for ophthalmic examinations. - It has a short duration of action, making it unsuitable for chronic conditions like overactive bladder. *Atropine* - **Atropine** is a non-selective **muscarinic antagonist** with a wide range of uses, including bradycardia, organophosphate poisoning, and ophthalmic procedures. - While it has antimuscarinic effects on the bladder, its systemic side effects (e.g., dry mouth, blurred vision, tachycardia) limit its use for overactive bladder. *Pirenzepine* - **Pirenzepine** is a selective **M1 muscarinic antagonist** primarily used to treat **peptic ulcers** by reducing gastric acid secretion. - Its selectivity for M1 receptors means it has limited efficacy for relieving bladder symptoms, which are primarily mediated by M2 and M3 receptors.

Q: Beta-blockers should be used with caution in patients with?

Conduction defect. ***Conduction defect*** - Beta-blockers **slow heart rate** and **decrease AV nodal conduction**, which can worsen pre-existing conduction defects like **AV block** or **sick sinus syndrome**. - Their use can lead to **symptomatic bradycardia** or complete heart block in susceptible individuals. - This represents a **strong relative contraindication** requiring significant caution. *Hypertension* - Beta-blockers are a **first-line treatment for hypertension**, effectively lowering blood pressure by reducing cardiac output and renin release. - They are generally **well-tolerated** and beneficial in most hypertensive patients. *Glaucoma* - Topical beta-blockers, such as **timolol**, are a common treatment for open-angle glaucoma as they **reduce aqueous humor production**, thereby lowering intraocular pressure. - Systemic use of beta-blockers does not typically worsen glaucoma and may even offer some benefit. *CHF* - While certain beta-blockers (**carvedilol, metoprolol succinate, bisoprolol**) are now proven beneficial in **chronic heart failure with reduced ejection fraction (HFrEF)**, they do require careful use. - They must be **initiated at low doses and carefully titrated** to avoid acute decompensation, and are **contraindicated in acute decompensated heart failure**. - However, **conduction defects** represent a **stronger contraindication** where beta-blockers can cause life-threatening bradycardia or complete heart block, making it the best answer for conditions requiring the most caution.

Q: Which of the following is a lipid insoluble beta-blocker?

Celiprolol. ***Celiprolol*** - **Celiprolol** is a **hydrophilic** (lipid-insoluble) beta-blocker, meaning it has low lipid solubility and does not readily cross the blood-brain barrier. - This property reduces the likelihood of **CNS side effects** such as nightmares and insomnia. *Timolol* - **Timolol** is a **lipophilic** (lipid-soluble) beta-blocker, allowing it to penetrate the central nervous system. - Its high lipid solubility contributes to a higher incidence of **CNS side effects**. *Carvedilol* - **Carvedilol** is a **lipophilic** mixed alpha and beta-blocker, which means it can cross the blood-brain barrier. - This can lead to central nervous system effects, although its primary clinical use is in heart failure and hypertension. *Pindolol* - **Pindolol** is a **lipophilic** beta-blocker with intrinsic sympathomimetic activity (ISA). - Its lipid solubility allows it to enter the brain, potentially causing **CNS-related side effects**.

Q: Hyoscine is an antagonist at which cholinergic receptor?

Muscarinic. ***Muscarinic*** - **Hyoscine** (scopolamine) is a well-known **antagonist** at **muscarinic cholinergic receptors**. - It blocks the action of **acetylcholine** at these receptors, leading to its anticholinergic effects like treating motion sickness and reducing secretions. *Nicotinic* - **Hyoscine** does not primarily act on **nicotinic cholinergic receptors**. - Drugs acting on nicotinic receptors include **neuromuscular blockers** (e.g., succinylcholine, rocuronium) and **ganglionic blockers**, which have different clinical applications. *Both* - While some drugs may have activity at both receptor types, **hyoscine's primary and clinically significant antagonism is at muscarinic receptors**. - Its therapeutic effects are attributed almost exclusively to its **muscarinic blockade**. *None of the above* - This option is incorrect because **hyoscine is a clear antagonist at muscarinic cholinergic receptors**. - Its widespread use in medicine is based on this specific pharmacological action.

Q: Fenoldopam is used in the management of?

Hypertensive emergencies. ***Hypertensive emergencies*** - **Fenoldopam** is a **dopamine D1 receptor agonist** that causes rapid, dose-dependent peripheral vasodilation and increased renal blood flow, making it suitable for acute blood pressure reduction during hypertensive emergencies. - Its **rapid onset** and short half-life allow for precise control of blood pressure, and its **benefit** in preserving or improving renal function is particularly beneficial in patients with renal impairment. *Congestive heart failure* - While fenoldopam can increase renal blood flow, it is not a primary treatment for **congestive heart failure (CHF)** and is not typically used for its management. - Other drug classes, such as **diuretics**, **ACE inhibitors**, and **beta-blockers**, are the mainstays of CHF treatment. *Migraine prophylaxis* - Fenoldopam has **no role** in the prevention or acute treatment of migraines. - **Beta-blockers**, **calcium channel blockers**, and certain **antidepressants** are commonly used for migraine prophylaxis. *Tachyarrhythmias* - Fenoldopam **does not have antiarrhythmic properties** and is not indicated for the treatment of tachyarrhythmias. - **Beta-blockers**, **calcium channel blockers**, and specific **antiarrhythmic drugs** are used to manage tachyarrhythmias.

Q: Which diuretic is known to cause the maximum potassium loss?

Furosemide. ***Furosemide*** - Furosemide is a **loop diuretic** that inhibits the Na-K-2Cl cotransporter in the **thick ascending limb of the loop of Henle**, leading to significant excretion of sodium, chloride, potassium, and water. - Its potent diuresis and impact on potassium reabsorption result in a **high risk of hypokalemia**. *Thiazide* - Thiazide diuretics inhibit the **Na-Cl cotransporter** in the **distal convoluted tubule**, causing moderate sodium and water excretion, and some potassium loss. - While they can cause hypokalemia, their effect on potassium excretion is generally **less pronounced than loop diuretics**. *Acetazolamide* - Acetazolamide is a **carbonic anhydrase inhibitor** that acts primarily in the **proximal tubule**, inhibiting bicarbonate reabsorption and leading to increased excretion of bicarbonate, sodium, potassium, and water. - The potassium loss is due to increased delivery of sodium to the collecting duct, leading to enhanced potassium secretion, but it is typically **less severe than with loop diuretics**. *Spironolactone* - Spironolactone is a **potassium-sparing diuretic** that acts as an **aldosterone antagonist** in the collecting duct, inhibiting sodium reabsorption and potassium secretion. - Instead of causing potassium loss, spironolactone actually **conserves potassium** and can lead to hyperkalemia.

Question 1

Which anti-cholinesterase drug is known for its central nervous system activity?

Accepted Answer

Physostigmine

Answer

Edrophonium

Answer

Pyridostigmine

Answer

Neostigmine

Question 2

What is a contraindication of antimuscarinic drugs?

Accepted Answer

Glaucoma

Answer

Peptic ulcer

Answer

Asthma

Answer

Urinary incontinence

Question 3

Maximum cycloplegic action of atropine is seen at ?

Accepted Answer

1-3 hours

Answer

1-2 weeks

Answer

4-6 hours

Answer

30-60 minutes

Question 4

Which of the following is NOT a side effect of atropine?

Accepted Answer

Diarrhoea

Answer

Urinary retention

Answer

Confusion of elderly

Answer

Blurring of vision

Question 5

Which antimuscarinic drug is used in overactive bladder?

Accepted Answer

Trospium

Answer

Atropine

Answer

Tropicamide

Answer

Pirenzepine

Question 6

Beta-blockers should be used with caution in patients with?

Accepted Answer

Conduction defect

Answer

Hypertension

Answer

CHF

Answer

Glaucoma

Question 7

Which of the following is a lipid insoluble beta-blocker?

Accepted Answer

Celiprolol

Answer

Timolol

Answer

Carvedilol

Answer

Pindolol

Question 8

Hyoscine is an antagonist at which cholinergic receptor?

Accepted Answer

Muscarinic

Answer

Nicotinic

Answer

Both

Answer

None of the above

Question 9

Fenoldopam is used in the management of?

Accepted Answer

Hypertensive emergencies

Answer

Congestive heart failure

Answer

Migraine prophylaxis

Answer

Tachyarrhythmias

Question 10

Which diuretic is known to cause the maximum potassium loss?

Accepted Answer

Furosemide

Answer

Spironolactone

Answer

Thiazide diuretics

Answer

Acetazolamide

NEET-PG 2015 — Pharmacology